Learn to use the beauty and skin care products.

School Science Lessons
Chemistry
2025-08-19
Household
Contents
19.1.0 Beauty and skin care products
19.2.0 Cooking
19.3.0 Home chemicals
19.4.0 Household fabrics

19.1.0 Beauty and skin care products
19.1.1 Hair and hair products
19.1.2 Lipstick
19.1.3 Perfumes and smells
19.4.4 Shampoo
19.1.5 Sunscreens and sun-protective clothing

19.2.0 Cooking
19.2.01 Cooking
19.21 Meat, anatomy and physiology
19.2.2 Baking and retention of nutrients
19.2.3.0 Browning
19.2.4 Cooking safety
19.2.5 Food colouring and ADHD
19.2.6 Meat treatments
19.2.8.0 Roasting meat
19.2.9 Sous vide cooking with a Ziploc bag
19.2.10 "Sphereification"
19.2.11 Taste, smell, flavour
Experiments
19.2.12 Boiling, test the cooking water of boiled vegetables
19.2.13 Mashed potato, pommes purée
19.2.14 Tests for dextrin in toast
19.2.15 Tests for iron in cooking water
19.2.16 Heat different foods

19.3.0 Home chemicals
19.3.1 Bases in the kitchen and laundry
19.3.2 Bath cleaning, borax
19.3.3 Metals in the kitchen
19.3.4 Paints, safety advice for paints and paint strippers
Experiments
10.6.3.1 Penetrating oil, e.g. WD-40
19.3.6 Prepare camphor oil
19.3.7 Prepare soap, household soap
19.3.8 Prepare preserving agents for cut flowers

19.4.0 Household fabrics
Experiments
19.4.1 Dyes
19.4.2 Dyes with a mordant
19.4.3 Prepare mordants
19.4.4 Permanent crease solution
19.4.5 Stain removal
19.4.6 Washing clothes with washing soda

19.2.3.0 Browning
19.2.3.1 Browning reactions of fruits and vegetables
19.2.3.2 Non-enzymatic browning, caramelization
19.2.3.3 Non-enzymatic browning, the Maillard reaction
Experiments
19.2.3.4 Tests for lemon juice effect on apple browning

19.2.8.0 Roasting meat
19.2.8.1 Roasting meat
19.2.8.2 Observe roasting meat
19.2.8.3 Toughness and flavour of cooked meat
19.2.8.4 Meat thermometer
Experiments
19.2.8.5 Cooked collagen changes into gelatine
19.2.8.6 Browning reaction is affected by temperature

19.2.01 Cooking
1. The four basic methods of cooking are as follows:
* Wet heating: boiling, steaming, pasteurization 100 oC to 120 oC,
* Dry heating: baking, roasting, up to 250 oC,
* Hot oil frying, up to 300 oC,
* Microwave cooking, up to 120 oC.
2. Cooking breaks down long molecules to smaller molecules that are more easily digested.
Cooking may also release flavours and destroy unwanted flavours.
Cooking may also raise temperature so that enzyme reactions can occur.
If meat is cooked too fast on a high flame the outside becomes scorched and covered with carbon that acts as a thermal insulator so that the meat takes longer to cook thoroughly.
So slow cooking results in more thorough cooking.
* Braising is done after browning the food in some fat then half immersing in liquid in sealed pot and cooked slowly.
* Broiling is the same as grilling in England, but in USA it means grilling food under direct heat source as in an electric oven.
* Caramelizing is browning of sugars in solution when heated above 150C.
The sugars breakdown to many compounds, including sugars, and carbon.
Onions are commonly caramelized.
* Frying is putting food into a bath of hot fat or oil.
It involves sealing and browning.
If the temperature does not exceed 180C, the fat or oil used should not break up or decompose.
The food should be dry or dipped into flour, bread crumbs or batter.
Potato is commonly deep fried.
If a fire occurs, drop in baking soda and cover the pan with a lid.
At temperature 300 oC, the wet potato chips sizzle, dry out and go brown on the outside.
* Poaching is cooking by simmering in water
Unlike boiling, the water temperature is kept below boiling point.
Eggs are commonly poached.
* Roasting is cooking food with dry heat and can be done in an oven or over an open fire.
Meat and poultry are commonly roasted.
Fish and vegetables can also be roasted.
* Sautéing and deglazing is briefly cooking food in a shallow pan for quick sealing and browning of small pieces of food.
However, The Concise Larousse Gastronomique defines "Saute" as follows:
" to cook meat, fish, or vegetables in fat until brown, using a frying pan (skillet) a saute pan or even a heavy saucepan and Deglaze: "to heat wine, stock or other liquid together with the cooking juices and sediment left in the pan after roasting or sautéing to make a sauce or gravy".
3. Woks are used mainly in Chinese cooking where all the food is first chopped and peanut oil or other oils are added to swirl around to coat the bottom of the wok.
When the oil starts to smoke, add the chopped food.
The salt in cooking water increases the osmotic pressure of the water and stops the food losing desirable flavour molecules by diffusion.
Food cooked in saltwater is no more salty than food cooked in unsalted water, unless you drink the cooking liquid.
4. Cooking time is proportional to the square of the smallest radius of the food rather than its weight.
Experiments
4.1 Taste raw and cooked to note the difference in flavour of different foods raw, cooked without salt, and cooked with salt:
rice or wheat flour, banana, peanut, bean curd, onion, beef, fish.
4.2 Try to eat raw potato, raw rice and raw meat!
Cooking breaks down inedible and indigestible large molecules and fibres to smaller structures that can be eaten and digested.
Similarly cooking destroys some bad flavours, poisons, bacteria and other organisms that may be harmful if eaten in raw food.

19.2.11 Taste, smell, flavour
Tastes, smells and flavours are usually due to many chemical components. For example, a recent study of the favour of the orange cultivar Kozan in Turkey found 34 components of flavour, including seven esters, two aldehydes, five alcohols, five terpenes, twelve terpenols, and three ketones.
The major flavour components: | Ethyl 3-hydroxyhexanoate, C8H16O3 | Linalool, C10H18O, (CH3)2C=CH(CH2)2C(CH3)(OH)CH=CH2 | Limonene, C10H16 | Phellandrene, C10H16 | Terpineol, C10H18O |.
Taste
The four basic tastes are sweet, sour, bitter and salt, also "umami", the savoury taste of glutamates, monosodium glutamate.
1. Sweet - Different sugars have different sweetness.
2. Sour - Acids always taste sour.
3. Bitter - Most alkaloids taste bitter:
Purgative aloes (Aloe vera), and wormwood (Artemisia absinthium) are used in absinthe | Lupulin, C30H46O11, in hops (Humulus lupulus) is used in making bitter beer.
Amygdalin, C20H27NO1, in bitter almonds (Prunus amygdalus) | Colocynthin, C38H54O13, in bitter apple (Citrullus colocynthis).
Quininne, C20H24N2O2, in bark of (Cinchona officinalis) and used in tonic water | Caffeine, C8H10N4O2 in ( Coffea arabica) and used in coffee.
4. Salt - Most sodium salts and most chlorides taste salty.
5. Umami - The taste of monosodium glutamate used in Asian cooking and Parmesan cheese.
The "trigeminal sense" allows us to "taste" chillies and onions.
Smell - The sense of smell depends on small molecules that can be carried in the air, e.g. from ripening fruit and flowers.
Also, air from the back of the mouth carry molecules from the food being chewed up to the olfactory epithelium of the nasal cavities, the "after taste".
Cooked food tastes differently from uncooked food, e.g. uncooked meat is relatively tasteless.
People who lack the sense of smell are called anosmic, they suffer from anosmia.
People who lack the sense of taste are called ageusic, they suffer from ageusia.
Reduced ability to smell is called hyposmia.
Reduced ability to taste sweet, sour, bitter or salty food is called hypogeusia.
Flavour - The flavour is the quality perceived by the sense of taste assisted by the sense of smell.
Experiments
1. Test blindfolded students for their ability to identify food with some students with nose clips or holding their noses:.
* Bland and tasty foods, e.g. potato crisps.
* Whole foods and pureed foods.
* Raw and cooked vegetables.
Be careful if using raw onions or chillies, because students may be allergic to them.
* Tomato and monosodium glutamate.
* Table salt and sugar.
* Note the difference between olive oil and a similar oil, e.g. safflower oil.
Then try to identify the oils when blind-folded and the nose pinched.

19.2.1 Meat, anatomy and physiology
1. Meat consists of muscle fibres, connective tissues and fats.
The muscle fibres largely consist of two proteins, myosin and actin, extended along the fibres and can move past one another, to cause a similar contraction.
Meat is muscles attached to bones by tendons.
Muscles contain long protein fibres actin and myosin.
These fibres slide along each other when stimulated by nerve impulses, which make the muscle shorter and fatter.
If muscles are used for short, fast bursts of energy, then glucose from the blood provides the fuel.
If the muscles give long sustained activity, then fat provides the energy and a protein, myoglobin, (MB), is needed to help oxidize the fat and provide the energy.
Myoglobin is a single chain protein of 153 amino acids, containing a haem, (heme), which is the main oxygen carrying pigment of muscle tissues.
Myoglobin is bright red, so muscles that work a lot are red while those that are used for less regular, sudden movements are pale or even white.
2. Fibrous tissues that surround the muscles and connect them to the tendons and bones are made from collagen.
The more collagen in the meat, the tougher it is.
There are three main types of connective tissue: collagen, reticulin and elastin.
Collagen is the most abundant and the most important for the cook to appreciate.
Collagen is a complex molecule made up from three strands that are twisted together rather like a rope.
Collagen derives its stiffness and strength from the arrangement of these intertwined helices.
However, if collagen is heated to temperatures above about 60 oC, the three strands can separate and the material loses its strength.
Once denatured into single strands, collagen becomes a very soft material, and is given a different name, gelatine.
You already know that gelatine is a soft, tender, material, since it is used as the basis of all jellies.
The collagen is mostly found around bundles of muscle fibres and helps to hold them together.
The muscles are then joined to the bones with yet more sinews (yet more "connective tissue"), which cooks recognize as tough "gristly" material.
These sinews are made from the proteins reticulin and elastin.
Reticulin and elastin can only be denatured and softened by heating for very long times at temperatures above 90 oC.
3. Muscles consist of bundles of long cells called muscle fibres or myofibrils.
Resting myofibrils contain two types of proteins actin and myosin arranged side by side.
The muscle contracts when the actin and myosin proteins slide together like the finger from each hand to form the protein actomysin.
This contraction occurs in the presence of calcium ions Ca2+, powered by the energy-carrying molecule ATP, (adenosine triphosphate).
After an animal is slaughtered, blood circulation stops, and muscles exhaust their oxygen supply.
Muscle can no longer use oxygen to generate ATP and turn to anaerobic glycolysis. The breakdown of glycogen produces enough energy to contract the muscles, and also produces lactic acid.
With no blood flow to carry the lactic acid away, the acid builds up in the muscle tissue.
If the acid content is too high, the meat loses its water binding ability and becomes pale and watery.
If the acid is too low, the meat will be tough and dry.
As glycogen supplies are depleted, ATP regeneration stops, and the actin and myosin remain closed in a permanent contraction of actomysin called rigor mortis.
4. Freezing the carcass too soon after death keeps the proteins all bunched together, resulting in very tough meat.
Individual protein molecules in raw meat are wound in coils, which are formed and held together by bonds.
When meat is heated, the bonds break and the protein molecule unwinds.
Heat also shrinks the muscle fibres both in diameter and in length as water is squeezed out and the protein molecules recombine, or coagulate.
Because the natural structure of the protein changes, this process of breaking, unwinding, and coagulating is called denaturing.
Most animal muscle is roughly 75% water, 20% protein, and 5% fat, carbohydrates, and assorted proteins.
Observe the arrangement of bone muscle, tendons and connective tissue is a piece of meat selected for roasting.
Mature beef should have areas of muscle separated by fat, an arrangement called marbling.

19.2.12 Boiling, test the cooking water of boiled vegetables
Meat cooked in hot water has no roasted flavours, because the temperature does not rise above 100 oC.
Vegetables with large surface / mass ratios (e.g. spinach) are especially sensitive to loss of vitamins.
Vitamin C is a most unstable nutrient in neutral and alkaline conditions.
In the presence of oxygen, folic acid may be even more unstable, and thiamine, riboflavin, carotene and niacin are sensitive under certain conditions.
Nutrient losses increase if large amounts of cooking water are used.
Cooking for longer times also results in a greater loss of nutrients.
Experiments
Test cooking water of boiled vegetables.
1. Boil green vegetables in water, e.g. spinach brussels sprouts, spring greens.
Removed the cooked vegetables and filter the cooled cooking water.
Observe the green colour of the cooking water, because of β-carotene, vitamin A precursor.
Test the cooking water for vitamin C with a Vitamin C dipstick.
2. Put some unpeeled new potatoes into boiling water for different lengths of time.
Remove them and cut them open.
Observe the growth with time of a translucent ring from the outside.
Inside the ring the potato still has an opaque white texture.
The width of the ring is the distance that has reached a temperature of 60 oC.
3. Put dry peas in a measuring cylinder and measure the volume of water needed to fill the cylinder to the 100 mL mark.
Put the peas in boiling water for 15 minutes boiling.
Put the boiled dry peas in the measuring cylinder and measure the volume of water needed to fill the cylinder to the 100 mL mark.
Calculate the percentage change in the volume of the peas.
4. Use a microscope to observe the characteristic shape of starch grains, e.g. potato, rice, wheat, maize.
Boil the starch grains until the cells burst and the starch forms a gelatinous mass leaving empty cell wall envelopes "ghosts".
This gelating action occurs at different temperatures: | barley 51 oC to 61 oC | tapioca 52 oC to 64 oC | pea 57 oC to 70 oC | potato 58 oC. to 66 oC | wheat 50 oC to 64 oC | maize (corn) 62 oC to 70 oC | rice 68 oC to 70 oC |.
5. Show the effect of the salivary enzyme amylase on raw and boiled starch measured using dipsticks specific for glucose.
6. Show that vitamins and minerals may be lost in the water vegetables are boiled in, e.g. spinach, Brussels sprout.
Note the colouring of β-carotene, vitamin A precursor in the water used for boiling.
7. Drop small pieces of raw and cooked liver into test-tubes containing 10 vols (3%) hydrogen peroxide.
Compare the rate of effervescence, because of the enzyme peroxidase catalase.
The same experiment can be repeated by using slices of raw and cooked potato.

19.2.15 Tests for iron in cooking water
1. Use a mixture of 1% potassium ferrocyanide and 1% hydrochloric acid to make potassium ferrocyanide.
A deep blue precipitate shows iron.
Boil water for a long time in a clean iron pot.
The cooled water may test positive for iron and this iron may be an important source of iron in some countries.
2. Tests for iron in the water vegetables were boiled in.
Add to a sample of the cooking water 1% potassium ferrocyanide and 1% hydrochloric acid, mixed just before use.
A deep blue precipitate indicates iron.
In some cultures the iron in the diet may come from the use of iron pots.

19.2.16 Heat different foods
1. Prepare in separate test-tubes small samples of the following:
* Carbohydrate, e.g. starch or sugar
* Fat, e.g. butter
* Protein, e.g. meat.
Heat the samples gently, then more strongly until they begin to burn.
Burning carbohydrates have a smell of caramel.
Burning fats produce acrolein that makes the eyes water.
Heated proteins produce ammonia-like compounds with different odours.
Continue heating each sample until only a residue of carbon remains.
The three food samples decompose on heating to leave a black solid, carbon.
Clean the test-tubes without delay.
2. Put a small sample of starch in a test-tube.
Hold the test-tube almost horizontally and heat the starch over a flame.
Be careful! Hot glass can cause severe skin burns so wear thick protective gloves and handle with care.
Note the liquid that appears nearest the flame at the bottom of the test-tube.
Test the liquid for water with cobalt (II) chloride.
The cobalt chloride turns blue so the liquid is water.
Starch is insoluble in cold water. but in hot water it forms a solution that may set like a jelly when cooled.
3. Repeat the experiment with the same quantity of the following:
3.1 Granulated sugar
3.2 Olive oil
3.3 Boiled egg white.
When testing the egg white, note the appearance of a thick, white mist and an ammonia-like smell.
Hold a moistened strip of red litmus paper in the mist.
It turns blue.
Only the egg white produces this reaction, because only it contains nitrogen.
4. Heat food with copper (II) oxide in a small test-tube.
Copper oxide releases oxygen to the food.
Test the gas in the test-tube with limewater by withdrawing gas with a medicine dropper, teat pipette, then expel the gas as a bubble through limewater.
The gas is carbon dioxide.
Copper (II) oxide releases oxygen to the food.
Also, note the water condensed in the cooler parts of the test-tube.
5. All carbohydrates decompose on heating to form carbon as a black solid.
Put glucose into a test-tube then heat gently strongly until only a black residue of carbon remains.
Clean the test-tube immediately.
6. Put glucose in a test-tube.
Note its crystalline state at room temperature.
Add water and sand, then heat until it decomposes to carbon dioxide and water.
Taste is sweet.
Cane sugar is crystalline starch and cellulose.
Cane sugar is readily soluble in water, cellulose is not.

19.2.13 Mashed potato, pommes purée
Two types of potato are as follows:.
1. The floury type with cells that separate and that breakdown easily when cooked, e.g. "King Edward".
2. The waxy type with cells that are firmly held together when cooked, e.g. "Charlotte".
Most new potatoes are waxy type.
Floury types make a mashed potato that is light, fluffy, and thick.
Waxy types make mashed potato that is thick, smooth and silky textured.
Floury types contain more starch granules per cell than waxy types and are more dense.
The cells contain starch granules.
The cell walls are a network of cellulose held together by hemi-cellulose.
During cooking, the hemi-cellulose breaks down, the cell walls get weaker, the cells start to separate and break open.
The starch granules absorb water and expand.
Many granules are also released from the cells of the floury types.
Prevent potatoes from absorbing water during cooking, which makes the mashed potato wet, by either cooking them in their skins or first peel then steam them.
Also, you can cook them at a temperature below the boiling point, leave to cool, then cook again before they are mashed.
The first cooking activates enzymes, which allow the pectin to react with calcium to make a glue to hold the cells together during the second cooking.
Mash potatoes so that the cells are opened without breaking the released starch granules to form an unpleasant sticky jelly.
Experiments
Use iodine solution to examine slices of floury type and waxy type potatoes.
Also, examine the starch grains before and after cooking.

19.2.2 Baking and retention of nutrients
Retention of nutrients may be low, e.g. vitamin C retention in baked apple 40%, thiamine retention in potatoes 41%.
Baking powders destroy thiamine that needs slightly acid conditions to keep stable during baking.
Bread loses little nutritional value during baking, but toasting causes loss of protein and vitamins, depending on how much drying out and browning.
The heating, rolling and flaking processes to manufacture breakfast cereals do not affect protein content.
Explosion puffing, e.g. puffed wheat, and puffed rice, does reduce the nutritive value, but these foods are usually eaten with milk.

19.2.14 Tests for dextrin in toast
Heated starch breaks into shorter length polymers called dextrin, C6H10O5)n.
Experiments
1. Prepare an iodine solution with 1 g iodine, 2 g potassium iodide 100 mL of water.
Starch gives a blue black colour.
Dextrins give a brown red colour.
Very small dextrin give no colour.
2. Prepare toast with a thin slice and a thick slice of bread.
Grind the toast to fine crumbs.
Shake the crumbs with water and filter with a Buchner funnel.
Add ammonium sulfate to precipitate starch and leave dextrin in solution.
Tests for dextrin with iodine solution.
The thin slice produces more dextrin than the thick slice.

19.2.3.1 Browning reactions of fruits and vegetables
1. Phenolase browning occurs at the cut surface of light-coloured fruits and vegetables For example brownin occurs in apples, bananas, and potatoes, where phenols oxidize to orthoquines, which then polymerize to form melanin brown pigment.
The phenolases, the enzymes that catalyse the phenols oxidation, contain copper.
Phenolase are active in the pH 5 to 7 range and can become inactivated below pH 3.
Phenolase browning is an enzymatic catalytic reaction.
Other browning reactions of food are non-enzymatic reactions, e.g. Maillard reaction, caramelization, and ascorbic acid oxidation.
When plant tissues are damaged, polyphenolic substances from the cell vacuoles contract the oxidase phenolase in the cytoplasm of plant cells.
In the presence of oxygen, /this chemica activity produce substances that protect the plant and favour wound healing.
However, these substances produce a brown coloration.
2. Brownning of the cut surface of fruits and vegetables is caused by polyphenoloxidases enzymes, released by the broken cells.
Thee enzymes catalyse the reaction between colourless polyphenols and molecular oxygen to create coloured compounds.
These coloured compounds can react with each to form black-brown melanins.
Cooking and food processing uses procedures to inhibit the action of polyphenoloxidases.
For example, cook may put freshly peeled potatoes into a pan of water and squeeze drops of lemon juice on to a freshly-cut avocado.
The change from a colourless solution of catechol to coloured benzoquinone can be followed by using a colorimeter.
If a fruit extract is added to a catechol solution, the rate of formation of coloured benzoquinone can be measured.
The faster the rate of increase in absorbance of the reaction mixture, the greater the polyphenoloxidase activity of the fruit extract.
An enzyme extract is adsorbed to filter paper discs.
These discs initially sink in a hydrogen peroxide solution, but then float to the surface as the oxygen produced gets trapped in the paper fibres.
The time taken for the discs to rise can be measured.
4. Phosphatase enzymes provide the phosphate ions used for many biological processes, e.g. the formation of ATP and nucleotides.
Some phosphatases are specific for a particular substrate, e.g. Glucose-6-phosphatase, but others can produce phosphate groups from many organic substrates.
Experiments
Phenolphthalein phosphate (PPP) is colourless in alkaline solution and free phenolphthalein is a pink colour.
The amount of enzymatic activity can thus be estimated by the intensity of colour produced from a standard rmixture when an alkali, e.g. sodium carbonate solution is added.
The phosphatase enzyme has an optimum pH of around 5, so the pH of the reactions should be kept below pH 9.2.
Buffer tablets may be used.
Use duplicates of the investigation so that colorimeter readings for each pair may be compared.
5. Browning can be prevented by the following processes:
* Immersion in water or dilute salt solution or coating with syrup so that the substrate has no contact with oxygen.
Concentrated sugar solution also depresses enzyme activity.
Also, storage in carbon dioxide or nitrogen prevents the browning reaction.
* Boiling or steaming to inactivate the protein enzymes that are denatured by heat.
Browning does not occur in cooked fruits and vegetables.
* Adding acid to lower the pH, e.g. lemon juice or cream of tartar, (potassium hydrogen tartrate, KHC4H4O7.
Ascorbic acid may also act as an antioxidant to reduce quinones.
* Lower the temperature to depress enzyme activity.
However, some fruits become brown even when frozen, e.g. banana skin.
* Use sulfur dioxide or sulfites, e.g. sodium sulfite, sodium metabisulfite, that react with quinones formed from phenolic compounds to block further reactions.
A sulfur dioxide concentration of 10 ppm (10 mg per litre), inhibits phenolase.
Sulfites are used in the processing of dried fruits, red wine, red and white grape juice.
However, sulfites may cause medical problems to people who have sulfite sensitivity.
* Dehydration makes phenolase inactive, even in bananas.
Browning may be a useful process as when plums become prunes, grapes become raisins and green tea leaves become black tea.
* Lemon juice contains two components that can block the browning reaction:.
1. Organic acids, mainly citric acid, with pH < 2, that lower the pH of the apple tissue below the best pH for the action of oxidases.
2. The biological antioxidant vitamin C that is oxidized to colourless substances.
* Test the effects of anti-browning compounds by using cut slices of celeriac or celery.

19.2.3.4 Tests for lemon juice effect on apple browning
1. Put a slice of fresh apple on a sheet of wax paper.
Examine the exposed moist surface with a magnifying glass.
2. Every minute, take another look at the apple and note any change in appearance.
After 5 minutes, remove the skin of the apple and describe the appearance of this newly exposed fruit surface.
3. Use two new slices of apple.
Place them side by side on a fresh sheet of wax paper.
Soak the end of a cotton swab in lemon juice.
Use this swab to paint the exposed surface of one of the apple slices.
Every minute, re-examine the apple slices.
Describe any changes and note whether both slices change at the same rate.
4. Repeat the experiment with two new slices of apple.
Crush a vitamin C table and grind it to a powder.
Rub the powder on one of the apple slices.
Note any changes in the cut surfaces of the apple slices.

19.2.3.2 Non-enzymatic browning, caramelization
Non-enzymatic browning is a chemical process that produces a brown colour in foods without the activity of enzymes.
Caramelization is the oxidation of sugar, used in cooking to release volatile chemicals to produce characteristic caramel flavour and brown colour.
The complicated chemical processes are not fully understood include:
* sucrose inversion to fructose and glucose,
* condensation to result in the formation of carbon,
* isomerization of aldoses to ketoses,
* dehydration,
* fragmentation reactions and unsaturated polymer formation,
* and production of melanins.
Caramelization temperatures of different sugars include the following: Fructose 110 oC, Galactose 160 oC, Glucose 160 oC, Maltose 180 oC, Sucrose 160 oC.
The brown colour may be due to fructose dianhydride and carbon particles.
Caramel is used as a flavouring and food colouring E150 in candy and Coca Cola and other foods.
The melting point of sucrose is 186 oC.
The solubility of sucrose is 2.59 g sucrose per g water at 50 oC.
Be careful!
"Toffee" burns are very painful and dangerous!
Wear a full face mask and gloves, because sputtering of hot sugar may occur.
Experiments
1. Add two measures of sugar to one measure of water.
Stir and heat in a Pyrex beaker or non-stick deep pot until all the sugar is dissolved.
Keep heating and adding more sugar until no more can dissolve.
Remove the heat when the solution has a straw colour.
Do not allow boiling to occur.
You can check the temperature of the solution with a special "candy thermometer".
Pour the hot solution into paper cups and immediately clean the Pyrex beaker or saucepan.
Leave to cool.
The glassy solid may be eaten or used in movie sets for imitation glass bottles and windows This is why actors are not hurt when hit with a "bottle", or when they jump through a "glass window".
After removing the heat, and while the solution is still hot, add whipped cream and butter to make the French desert "creme brulee", ("burnt custard").
2. Put granulated sugar or glucose in a shallow porcelain-lined evaporating dish or metal pan, volume X10 the volume of sugar / glucose.
Heat the sugar over an electric stove until it froths up suddenly, immediately turn off the stove or remove the dish or pan from the stove.
Add water to bring the dark brown viscid mass to the consistency of a heavy syrup.
The product will be insoluble in water if more than 15% of the original weight of the sugar is lost.
If the caramel dissolved in water is cloudy, carbonization has occurred so some of the sugar has been reduced to carbon.

19.2.3.3 Non-enzymatic browning, the Maillard reaction
The Maillard reaction, first discovered by Louis Camille Maillard, France, in 1912, refers to the chemical reactions between:
1. the aldehydes and ketones from reducing sugars, and
2. proteins or amino acids, e.g. asparagine, to form more than 200 mainly brown new chemicals with strong, distinctive smells and tastes.
The reactive carbonyl group of the sugar interacts with the amino group of the amino acid.
The type of amino acid decides the many flavour compounds produced and these compounds may then breakdown to form more new flavour compounds For example, the aroma compound, 2-acetylpyrroline, C6H9NO, occurs in toast.
The Maillard reactions are used to produce:,BR> caramel candies made from milk and sugar, the browning of bread in toast, cakes, stir fries, malting of barley to give the colour of beer, chocolate, roasted coffee beans, maple syrup, lightly roasted peanuts, colour of condensed milk, potato chips and baked potatoes.
The carbonyl group of the sugar reacts with the amino group of the amino acid, producing water and N-substituted glycosylamine.
It undergoes Amadori rearrangement to form ketosamines, which react further to produce various short chain products, brown nitrogenous polymers and melanoidin.
The protein of meat congeals when heated.
If it is further heated after it has congealed, its combination is broken and it becomes a compound called melanoidin with a chemical amino carbonyl reaction to oxygen in air and others.
Melanoidins are polymers, the coloured final products of the Maillard reaction, but their chemical structures are not known.
They are possibly furans and pyrroles formed by cross-linking of degraded sugar products with lysine and arginine in meat protein.
They occur in coffee, cocoa, bread, malt, honey, sweet wine, and dark beer and cause the colour, viscosity and flavours in cooked and processed foods.
Melanoidins have antioxidant activity and antimicrobial activity, but the processes are not understood.
Melanoidin is light brown and has the good smell of grilled meat.
However, melanoidin is easy to volatize, so its smell disappears if it is heated for a long period of time with low heat.
It is why cooks grill meat for a short period of time over a high flame.
Over 200 oC, carbonization occurs and the protein component causes a bad smell.
Pentose sugars react more than hexoses, which react more than disaccharides.
Different amino acids produce different amounts of browning.
The temperature of meat in a microwave oven is never above 100 oC, so no maillard reaction can occur.
Cooks may "pre-brown" the surface of meat before cooking it in a microwave oven.
Sausages should be cooked at 120 oC -15 oC to maximize the Maillard reaction and produce brown, not black, cooked sausages.
Experiments
1. Make toast from white bread and brown bread or wholemeal bread.
Put equal thickness slices of white bread and brown bread or wholemeal bread in each side of a toaster.
Turn on the toaster and note the time taken for each slice to start to burn.
The brown bread or wholemeal bread slice burns faster than the white bread slice, because the white bread contains less sugar and protein for the Maillard reaction.
If the white bread slice is really white it may reflect more radiation from the toaster than darker slices.
2. Make caramel confectionery.
Boil together sugar and milk or butter until the solution turns brown.
You can check the temperature of the solution with a special "candy thermometer".
To make toffee, heat the solution to 160 oC, add baking soda and vinegar to make honeycomb toffee, and leave to cool.

19.2.8.1 Roasting meat
When muscle fibres are heated above about 40 oC the proteins start to denature.
In muscle proteins, which are extended along the muscle fibres, this change of shape involves the proteins coiling up.
This coiling process inevitably causes some contraction of the muscle.
Muscles contract during cooking so pieces of meat contract along the direction of the muscle fibres.
When the protein molecules are denatured, the muscles contract so the meat becomes harder.
The meat will be tough.
The cooking time should be long enough to degrade the connective tissue present in the meat, without toughening the muscle proteins.
The toughening occurs in two stages.
The first stage is caused by the muscle proteins that are extended along the muscle fibres contracting into coils as they denature.
The pieces of meat should be getting thinner during this stage as the fibres contract.
The second stage is the coagulation of the now denatured muscle proteins into lumpy, knotty masses.
There should be a much greater degree of toughening in this stage, but no noticeable changes in the shape of the pieces of meat.
Meat is roasted to 1. to make it tender to eat 2. to give it a roasted flavour 3. to kill any harmful bacteria 4. to create an acceptable warm temperature for eating when fats are still liquid.
Low temperature roasting.
Most cooks first brown the meat at a high temperature to seal in the meat juices during cooking before letting it cook through at a lower temperature.
High meat temperature makes the meat muscle contract, forcing liquid out.
However, cooking at less than 70 oC can produce tender meat before the meat is browned on the outside.
Slow cooking for a long time at a low temperature causes collagen in the meat to breakdown into gelatine and the meat fibres to shrink and release the meat juice to form a gravy.
The fibres separate easily and are tasty.
The high temperature surface searing of the meat following the slow cook creates lots of aroma molecules when the ribose and the amino acids released from the meat react together and these add to the rich flavour by the Maillard reaction.
This final heating also kills off any bacteria that may have survived the slow cooking.
To retain moisture, "rest" the meat after cooking so that as meat muscle fibres cool and widen, they hold on to more juice.

19.2.8.2 Observe roasting meat
The meat consists mainly of three materials: water, proteins and fat.
When a strong source of heat is applied to the surface of the meat, the protein coagulates and aggregates to form crust, possibly the result of the Maillard reaction as in the formation of crust on bread.
The presence of heat and water, will make the collagen, (the proteins present in meat), degrades to form a gelatine.
This the reason why the meat is removed and this brown crust appears at surface.
However, if the meat is warmed too long, the evaporation of the water associated to the coagulation of the other proteins in the surface, will have for inverse effect to dry and harden the meat.
It is necessary here all the art and the experience (experiment) of the cook to find the equivalence completed between these two opposite phenomena.
The chemistry of the browning of meat is still the subject of disagreement and further research.
Some chemists say that the Maillard reaction occurs when the denatured proteins on the surface of the meat recombine with the sugars present.
The combination creates the "meaty" flavour and changes the colour, the browning reaction.
When meat is cooked, the outside reaches a higher temperature than the inside, triggering the Maillard reaction and creating the strongest flavours on the surface.
As many as six hundred components have been identified in the aroma of beef.
However, if the Maillard reaction is strictly the reaction between an amino and a reducing sugar, there are not many reducing sugars in meat, so the browning of meat may be due more to the breakdown of tetrapyrrole rings in myoglobin, the muscle protein.
During roasting, different changes occur at different temperatures:.
40 oC Red muscle proteins denature, meat is still red.
55 oC to 60 oC Red muscle proteins coil and shrink.
Water bound to protein starts to flow.
The myosin molecules start to shrink and squeeze out fluid from the muscle cells.
Shrinking fibres makes the meat firmer.
60 oC to 65 oC Produces "rare meat" that is pink and juicy.
Muscle proteins start coagulating.
Collagen begins to denature and breakdown to form gelatine, which dissolves in water.
65 oC to 70 oC Produces grey protein.
Water bound to protein stops flowing.
Kills bacteria on the surface of the meat.
These bacteria may be harmless even if they cause meat to spoil.
The food poisoning bacteria (Salmonella) and (Escherichia coli), (E. coli), are killed above 68 oC.
However, minced meat may have surface bacteria mixed throughout the meat, so all the meat should reach that temperature 80 oC.
This produces "well done" meat that is brown grey and dry tough meat.
90 oC Collagen turns into gelatine.
100 oC to 120 oC Roast and fried flavours and brown colours form as proteins and carbohydrates breakdown into smaller sugar molecules and aldehydes and react with amino acids sulfur gives agreeable aromas so cooks add garlic or onions, because of their high sulfur content.
The meat smell is because of the molecule bis-2-methyl-3-furyl-disulfide.
Similar reactions gives the colour and flavour to bread crust, toast, biscuits and caramel toffee.
All these reactions are called the Maillard reaction, browning reaction, and they occur at above 140 oC.
Caramelization of sugars occurs at about 150 oC.
Above 200 oC, carcinogenic molecules may form in barbecued meat.

19.2.8.3 Toughness and flavour of cooked meat
Cut a slice of meat 10 equal size pieces.
Start cooking the pieces every 2 minutes in a frying pan or under a grill until all the pieces are being cooked then turn all the pieces every minute.
After the last piece has been cooking for 3 minutes turn off the heat.
Note the colour of each piece.
Test the pieces for toughness and flavour by 1. chewing 2. cutting with a blunt knife.
Pieces cooked for up to 8 minutes are probably tender, but pieces cooked for longer are increasingly tougher.
Note an increasing of flavour with cooking time.

19.2.8.5 Cooked collagen changes into gelatine
Collagen is an insoluble fibrous protein in connective tissue, e.g. tendons, skin, bone.
Use meat with lots of connective tissue and still connected to the bones with tendons, e.g. shin beef, oxtail.
Cut the meat and tendons into small pieces, and cover with water, heat to boiling and leave to simmer.
Do not allow all the water to evaporate!
After each 30 minutes remove 50 mL of the water and place in a container in a refrigerator.
After each removal of water replace with 50 mL of boiling water.
Water removed after about 2 hours simmering thickens on cooling until water removed after 3 hours forms jelly as it cools.
Collagen in meat and tendons heated to above 60 oC changes from its triple stranded helical form into a single stranded form, called gelatine.
Gelatine is soluble in water so its concentration increases as more collagen denatures during simmering.
When cold, high concentrations of gelatine molecules aggregate together in a loose gel or jelly.

19.2.8.6 Browning reaction is affected by temperature
Cook 8 pieces of meat at different temperatures.
Heat the oven until the temperature is steady at 100 oC.
Put in a piece of meat for the time listed below.
Raise the temperature of the oven and cook the next piece of meat.
Note the colour, and the occurrence of the cooked meat smells and tastes, and the burnt meat smells and tastes.
Cook each piece for half the cooking time for each side:
100 oC Cooking time 12 minutes, 120 oC Cooking time 9.5 minutes, 40 oC Cooking time 8 minutes.
160 oC Cooking time 7 minutes, 180 oC Cooking time 6 minutes, 200 oC Cooking time 5.5 minutes.
, 220 oC Cooking time 5 minutes, 240 oC Cooking time 4 minutes.
19.2.8.4 Meat thermometer

19.2.8.4 Meat thermometer
Scale:
turkey 83 oC, lamb 82 oC, beef - well done 77 oC, veal 77 oC, pork 77 oC, ham 71 oC, beef - medium done 71 oC, cooked ham 60 oC, meat - rare 60 oC.
Do not put the meat thermometer in water.

19.2.6 Meat treatments
1. Marinades are made of acid, oil, and herbs.
The acid is to denature the proteins and open the meat structure for flavour to enter.
Marinades work best on meats that are not too dense or where the meat is cut into pieces.
2. Salting meat, brining, adds moisture to the meat through osmosis, because the meat's cell fluids are less concentrated than the salt water.
Water leaves the muscle cells and salt flows in to dissolve fibre proteins and concentrate the cell fluids so water is attracted back into the meat.
So salting meat adds both salt and water to the meat muscle.
Not all the water is squeezed out by cooking, because of the added water.
3. Many flavour or aroma molecules cannot dissolve in water, but can dissolve in fat.
Muscles that are used often consume the stored fat, and so the meat from these muscles has little fat.
Older the animals have fat energy reserves in their muscles.
Meat with white streaks of fat is called marbled and gives beef with the best flavour.
Ageing allows enzymes in the muscle cells to breakdown the overlapping proteins, which makes the meat tender.

19.2.7.3 Microwave radiation
1. Microwaves are a form of high frequency radio waves similar to the waves used by AM and FM radio.
Microwaves enter from the outside of food losing about half their energy every 3 cm.
Microwaves are reflected by metals so the walls of the microwave oven are made of stainless steel or epoxy coated stainless steel, so that the microwaves can bounce around the inside and not escape into the kitchen.
Food is usually heated on a revolving turntable to produce an even heating and avoid hot spots and cold spots.
The holes in the steel door are too small to let the microwaves pass through.
Microwaves are transmitted by paper, glass and some plastics that do not absorb microwave energy and do not become hot.
Microwaves are absorbed by food containing moisture.
2. Microwave region of the electromagnetic spectrum is from frequency 300 MHz, wavelength 1 m, to 300 000 MHz, wavelength 1 mm.
Australia and UK, microwave ovens operate at 2450 MHz (Class B / Group 2, ISM equipment Standard CISPR11), wavelength 12 cm.
In other places, the microwave oven wavelength may be 12.24 cm.
This is a lower frequency and lower energy than ionizing radiation.
For safety reasons, when the microwave door is opened, switches must cut the power.
The power flux density of microwave radiation should not exceed 50 W / M2 at any point 5 cm or more from the external surface of the oven.
The inside of a microwave oven is coated with metal that acts like a Faraday cage and reflects the microwaves (radio waves).
3. Microwave radiation is generated in an electronic tube called a magnetron.
High voltage emits electrons from a heated cathode that are diverted by magnets to spin in a circular orbit causing metal plates to resonate and emit microwaves to be conducted into the interior space of a microwave oven (or connected to a radar transmitter).
The patterns of more intense radiation can be seen by placing thermal paper used for thermographic imaging at different heights in the microwave oven.
However, the same thermal paper placed on the turning turntable, (carousel), shows a more equal distribution of the radiation.
4. Water molecules are electric dipoles with a positive charge at one end and a negative charge at the other end, so they spin when they align with the alternating electric fields in the microwave oven.
However, a block of dry ice is not melted in a microwave oven, because the carbon dioxide molecule is not a dipole.
Experiment
Microwave ice
Put water in a plastic dish
Dry two ice cubes with a tea towel and put them in another plastic dish.
Put the plastic dishes in a microwave oven and turn on the oven for one minute.
Take out the plastic dishes then feel the temperature of the water and ice cubes.
The water feels hot.
A little ice has melted, but the ice feels cold.
The water in the ice cannot turn around, so it is difficult to defrost food in the microwave oven.

19.2.7.2 Microwave cooking
Microwave cooking occurs, because water is a strong absorber of microwaves, so the water in food boils and turns to steam.
In a normal oven, a range of black body radiation is generated, but only some longer sections of this radiation are absorbed by food.
The radiation penetrates the surface of the food for about one wavelength for infrared heat radiation < 1 / 10 mm.
Only the outside of the food is directly affected and the inside of the food is heated by conduction.
The 12 cm wavelength microwaves penetrate deeper into the food.
Avoid exploding food, e.g. tomatoes, apples, by cutting into them before microwave cooking.
Also avoid dry food with spikes or sharp corners For example, small pieces of sweet potato or broccoli may cause electrical arcing between the spikes or corners to cause charring of the food.
Elevate the cooking pan in the microwave oven to allow more bounce of microwaves up from the floor of the microwave oven and get more even cooking.
Microwaves are not used for defrosting, because ice has few free molecules of water to be excited by the microwaves.
Microwave ovens do not heat food by operating at a special resonance of water molecules in the food.
A microwave oven could operate at many frequencies.
The 22 GHz resonant frequency of isolated water molecules has a wavelength too short to penetrate common foodstuffs to useful depths.
The typical oven frequency of 2.45 GHz was chosen partly due to its ability to penetrate a food object of reasonable size.
Microwave ovens do not cook food from the inside out, because 2.45 GHz microwaves can only penetrate approximately 1 cm into most foods.
The inside portions of thicker foods are mainly heated by heat conducted from the outer portions.
Microwave ovens cannot cause cancer, because as microwave radiation is non-ionizing radiation.
Do microwaves make food radioactive?
The energy of a microwave photon in a microwave oven is 0.00001 eV, but the minimum ionization energy of common chemical substances is about 0.01 eV.
So microwave ovens do not cause chemical changes from radiating food.
Photons in an conventional infra-red oven are much higher energy.
However, but the energy required to change a nucleus / make something "radioactive" is many powers of ten higher.

19.2.7.1 Microwave containers
Microwave cooking containers should not absorb the radiation They should be made from material with low polarity, i.e. low dielectric constant and low dissipation factor at 2450 MHz.
The material should be stable at high temperature and have good resistance to oil vapour, e.g. polystyrene and certain glass.
Never use metal containers or plates decorated with metal leaf, because microwave cannot pass through metal and reflect to damage the magnetron.
Remove meal foil packaging and twisted ties or tags.
Do not use dishes with metallic rims, cups with glued-on handles, delicate glassware, cut glass vases, jars with metal lids.
However, you can use metal foil to protect food that might overcook in some areas.
Do not cook in plastic food storage bags, because they may melt.
However, "GLAD WRAP" may be used to cover dishes, but do not remove it immediately after cooking.
Do not use brown paper bags or newspaper, because they contain metallic impurities that may cause blue spark arcing and damage the oven.
Do not put mercury thermometers in the microwave oven.
Do not put a wet cat in the microwave oven.
Use containers labelled "microwave oven safe".
Use shallow round dishes, because microwaves penetrate only 2 to 3 cm into most food.
Food in the corners or dishes with corners will receive more energy and probably overcook.
Arrange food containers in a ring at outside of the rotating turntable.
Sometimes it pays to put the container containing thin food on top of another container on the turntable to get more bounce of microwaves through the food.
Remember that if food is not cooked through, e.g. poultry, then bacteria may remain unharmed inside.
Examples of microwave cooking containers:
* "Starmaid" baking dish, plastic, 1 litre with lid, 190 mm × 170 mm × 68 mm.
* "Décor Thermoglass", for conventional ovens and microwaves, with microwave safe lid with a steam release vent, 1 litre.
* Microsafe milk heating jug, "Microsafe" jug has cone-shaped lid if it boils, the milk flows up though the cone, safely back into the jug.
* Melamine crockery, green, virtually unbreakable, dishwasher safe.
Not suitable for microwave oven, plate, 18 mm diameter.

19.2.7.4 Superheating in a microwave oven
When tap water is heated on a stove top, the maximum superheating is 100.75 oC.
However, in a microwave oven, superheating temperatures of 105 oC to 110 oC can occur.
The microwave oven heats the water directly and the container indirectly, the opposite of what happens when heating a container of water on a stove.
In the microwave oven the water is not heated near the beaker surface where nucleation is most likely to occur.
Evaporation occurs only at the water surface and is not fast enough to cool the bulk water.
There is much less superheating in plastic cups, because water does not wet plastic and many more nucleation sites are available for boiling.
Do not put a cup of still water in a microwave oven, because when the cup is removed, nucleation may occur, water boils, forms steam, to scold your hand.
To avoid the delayed eruptive boiling of liquids after cooking, leave to stand for at least 20 seconds before removing food or liquids from the microwave oven.
This action allows for some cooling and more even distribution of heat.
If a plastic fork or tea bag is placed in the liquid before the microwave oven is turned on, they provide nucleation sites for boiling to occur, so no superheating.
Experiments
1. Test a container for potential microwave oven use.
Fill a one cup glass measure with water and put it in the microwave oven alongside the container to be tested, e.g. a ceramic dish.
Heat for on high for 60 seconds.
If the container is microwave oven safe, it will remain cool, but the water should be hot.
However, you cannot use this test on plastic containers that must be labelled microwave "oven safe".
2. Cook a potato for 2 minutes then cut it open to see the translucent areas finger-like regions extending from the outside where the potato has been heated above 60 oC.
This show that microwave ovens do not provide a uniform density of microwave energy.
So "hot spots" and "cold" spots may exist in microwave ovens, unlike the conventional oven.
This is the reason cooks suggest leaving food cooked by microwaves to "stand" for some time after cooking to allow the temperature to equalize in the food.
3. Compare popcorn cooked in the microwave with popcorn cooked on the conventional stove.
Use the same number of corn (maize) grains and later count the number of unpopped grains.
Carefully open popcorn bags away from your face!.
4. Do not put sealed tins or glass jars in a microwave oven, e.g. babies bottles fitted with a screw cap.
Remove food from tin cans.
If boiling liquids in a microwave oven use a wide moth container.
Also, puncture skins of potatoes, apples, sausages and oysters to allow steam to escape.
Food with a high fat content, e.g. sausage roils, may catch fire if overcooked.
5. Eggs cooked in the microwave oven.
Eggs may explode, so avoid exploding food by cutting into eggs before microwave cooking.
Egg yolk contains fat so tends to cook more quickly than egg white.
Even out of the shell, eggs may explode in the microwave, because rapid heating causes a build-up of steam, so before cooking puncture egg yolks and whites.
6. To observe the effect of the wavelength of microwaves, take out the turntable and put a one cup glass measure with water and a long stick of uncooked spaghetti.
Heat at high for one minute.
The spaghetti will have an uncooked area every 12 cm.

19.2.10 "Sphereification"
Alginic acid (alginate, algin C6H8O6, anionic polysaccharide, from brown algae "Sphereification" is a method of cooking invented by Spanish chefs
Juices are mixed with alginates (alginic acid), usually sodium alginate, then added drop by drop to calcium chloride solution.
The calcium salt causes rapid gelling of the outer thickness of the drop by electrostatic cross linking so a soft bead of juice is formed with a liquid centre.
The beads are called pearls, spheres, "ravioli".
The idea is that the beads can be easily crushed by the teeth to "explode" and release intensive taste substances.
The technique has been used for many juices, e.g. green tea, peach, liquidized olives.
Sodium alginate is also used in medicines to treat oesophageal reflux, e.g. Gaviscon.
Experiments
To make gel snakes, dissolve in 100 mL water 2g alginic acid sodium salt and 1g calcium chloride, add food colouring.
Use a syringe to squirt the alginic acid solution into calcium chloride solution to form gel snakes.

19.4.5 Stain removal
* Stain removal depends on solubility and chemical reactions.
Clean stains immediately to prevent further chemical bonding to the material.
Scrape off excess solid and soak up excess liquid.
Try the treatment first on an inconspicuous part of the material.
Work inward from the edge to prevent outward diffusion and spreading of the stain.
Do not rub.
Allow material to dry before consecutive treatments.
* Salt heated in the oven and rubbed into serge or gabardine will remove stains and grease spots.
* See 19.4.2.2 Stain removal table.

Treatments
1. Mixture of wool detergent with one teaspoon of clear vinegar in one litre of warm water.
2. Organic solvent, e.g. dry cleaning fluid, mineral turps, light petroleum.
Be careful! Ensure good ventilation and keep away from flame!.
Remove stains caused by fatty substances, e.g. chocolate, butter, or grease with dry cleaning solvents, e.g. tetrachloroethylene, CCl2=CCl2.
Dry cleaning refers to cleaning textiles with organic solvents rather than water, e.g. chlorinated hydrocarbons such as chlorinated ethylene are used.
3. Mixture of mineral turps with dry cleaning fluid.
Be careful! Ensure good ventilation and keep away from flame!
4. Methylated spirit.
Be careful! Ensure good ventilation and keep away from flame!
5. Hydrogen peroxide, 20 vols.
Dilute one part to 10 with cold water.
Do not use on dark or patterned material.
Much stain removal is done by oxidation using oxidizing bleaches, e.g. hydrogen peroxide, sodium perborate, sodium hypochlorite.
Do not use bleach on wool, because it attacks the chemical linkages that hold the wool together.
6. Dye stripper diluted one part to 50 with cold water.
Do not use on dark or patterned material.
7. Use a freezing agent to solidify the gum, and then scrape it off.
8. Acetone.
9. Clean, warm water.
Do not use hot water.
10. Cold water only.
11.19.4.2.3 Lemon juice stain remover
Lemon juice is used to stop fish smells and refrigerator smells, remove kettle "fur", and clean copper and stainless steel kitchen ware.
The juice is acidic, and the stain or smell may be acid soluble.
Lemon juice contains ascorbic acid, vitamin C, an active reducing agent, i.e. electron donor, that can reduce molecular oxygen.
If the stain is reduced by ascorbic acid to a substance that is not coloured, the lemon juice bleaches the stain.
The skin of lemons contains oils, e.g. lemon oil.
The stain may be soluble in the oil.
Most stains are because of organic chemicals that more soluble in the organic compounds in lemon juice then in water.
Lemon juice may convert the stains into substances that are more soluble in water or the lemon juice.
12. Absorbent powder, e.g. salt or talc.
Sprinkle on spillage, leave overnight, then vacuum off.
Use large amounts of salt on a fresh red wine stain on a table cloth before the red dye becomes attached to the cloth.
19.4.2.2 Stain removal table

beer 1.	chocolate 1. 2.	fruit juice 9. 2.	fountain pen ink 9. 1. 6.	oil-based paint 3. 2. 1.
beetroot 1.	cocoa 1. 2. 10.	furniture polish 2.	lipstick 1. 2.	rust 1. 2. 11
bleach 1.	coffee / tea 1. 2. 10.	grass 4.	mildew (fungus) 1. 5.	shoe polish 1. 2.
blood 10. 6.	cooking oils 1. 2.	gravy / sauce 1. 9.	milk 1. 2. 9.	soft drinks 1. 5. 9.
burn or scorch 5.	crayon / marker 2.	grease 2. 1.	nail polish 2. 8.	tar 1. 2. 3.
candle wax 3.	egg 1.	ice cream 1.	salad oil / dressing 1. 2.	red wine 6. 9. 12.
chewing gum 7.	faeces / urine / vomit 1.	ball point ink 1. 4.	paint, emulsion 1. 2. 10.	white wine 1.

19.4.1 Dyes
Boil the fabric for five minutes in 10% hydrochloric acid.
Mix 1 g Congo red or methylene blue powder, 4 g sodium hydrogen carbonate, 1 g sodium sulfate, 100 mL deionized water.
Slowly add the mixture to water while stirring.
Boil the fabric for 4 to 5 minutes and then rinse it in cold water and leave to dry.

19.4.2 Dyes with a mordant
A mordant is a substance that enables a dye or stain to become fixed to a fabric or tissue.
If you cannot dye a fabric directly, use a mordant that combines with the dye and forms an insoluble "lake" in the fibres.
A lake is a pigment formed by interaction of a dye and a "base" to metallic salts, oxides and hydroxides.
Mordants are hydroxides of aluminium, chromium and iron.
Experiments
1. Heat white cotton fabric for 10 minutes in a dilute solution of ammonium sulfate.
Then put it in dilute ammonia solution for 5 minutes.
Rinse the fabric in clean water and hang it up to dry.
Study the effect of the mordant by boiling the mordanted and unmordanted pieces of cotton in methylene blue solution for 5 minutes.
Rinse and dry.
Compare the colour of the fabrics.
2. Aluminium hydroxide, Al(OH)3, is a porous substance that can attach to fabrics and absorb dyes.
The aluminium salt hydrolyses to form hydroxide.
Dissolve 30 g of potassium alum, (alum, Al2(SO4)3.K2(SO4).24H2O, and 7 g of cream of tartar, (potassium hydrogen tartrate), in warm water, then add to 4.5 L of soft water warmed to 30 oC and stir well.
Very slowly add 120 g of evenly wetted wool, then heat to boiling while turning the wool to ensure even mordanting.
This process can take up to one hour.
After boiling point has been reached reduce the heat and let the mixture simmer for a further hour.
The wool is now ready for dyeing.

19.4.3 Prepare mordants
Wool: alum
Plant-based fibers, (cotton, linen, hemp), tannin and alum
Brown: Used ground coffee
Green: Azalea leaf
Purple: Red cabbage leaf
Yellow: Onion skin, marigold (Calendula officinalis) flowers
Red, Cochineal, C22H20O13, anthraquinone glucoside Heat plant material in water without boiling until dye appears. Experiments
Prepare a mordant.
Dissolve 3 g potash alum Al2(SO4)3.K2(SO4).24H2O, also shown as KAl(SO4)2.12H2O, in 100 mL hot water.
Dissolve 1 g cream of tartar in 100 mL hot water and then put these solutions into an old pot or saucepan.
Soak a woollen garment in the warmed mordant solution overnight.
Replace the mordant with the dye.
Put the woollen garment in the dye and observe the colour change in the wool.
Rinse the dyed garment with water and dry slowly.

19.4.6 Washing clothes with washing soda
When washing clothes you need to disperse clay particles and keep them in solution to be thrown away when the washing water is discarded and clothes are rinsed.
So washing soda, Na2CO3.10H2O, is added so the highly exchangeable sodium ions displace calcium ions.
Detergents use polyphosphates or zeolite to make calcium inactive in the system.

19.4.4 Permanent crease solution
Hair straightening, permanent wave
Sodium metabisulfite, Na2S2O5, sodium disulfite, sodium pyrosulfite
Fibrous proteins and globular proteins
Hair waving to hair straightening depends on chemical treatment of the disulfide bond in the protein Cysteine, C3H7NO2S.
The disulfide bonds that give proteins their macroscopic structure can be split at room temperature and slightly alkaline pH by the action of sulfides or mercaptans.
A reducing agent converts the (-S-S-) bonds to (-SH) groups.
The hair is combed to straighten and to wave it.
An oxidizing agent restores the (-S-S-) bonds to create straight hair or a "permanent wave".
Hairdressing salons use thioglycollic acid in a pH buffer and a cuticle softener to make the internal structure of the hair floppy.
This reaction produces the smell of rotten eggs from hairdressing salons!
After combing and setting the wet hair, the hairdresser neutralizes the thioglycollic acid with hydrogen peroxide so that new disulfide bonds form to keep the hair in the new shape.
Experiments
Prepare permanent crease solution
1. Make a 3% sodium metabisulfite solution and add a few drops of detergent.
Make a crease with two samples of woollen material.
Sponge the solution along the crease in one sample, then press the crease with a steam iron for 30 seconds.
On the other sample, press the crease with a steam iron for 30 seconds.
Immerse both samples in warm water.
Compare the creases.
The protein polymer in the treated wool has a "permanent " crease.
Repeat the experiment with human hair to achieve a "permanent wave".

19.3.4 Paints, safety advice for paints and paint strippers
1. Fire retardant paints contain substances that decompose on heating to give gases that do not support combustion, e.g. phosphates, tungstates, borates and carbonates.
Some of these substances fuse on heating to give a glass-like layer on the surface.
Other substances are not flammable, e.g. silicones, chlorinated resins, mineral powders.
Although water based plants may be non-flammable before use, they may become flammable when painted on a surface and dried.
2. Anti-fouling paints used in marine construction may contain inorganic poisons, e.g. Cu and Hg salts, or organic molecules, e.g. entachlorophenol or organo-tin groups in the polymer.
The later decompose to non-toxic inorganic tin on release into the sea water.
3. Fluorescent paints absorb ultraviolet radiation and re-emit it as visible light when irradiated.
They contain zinc and cadmium sulfides, and organic dyes.
4. Phosphorescent paints are irradiated with ultraviolet light and continue to glow in the dark after the irradiation has stopped.
Phosphors may include ZnS (green, yellow, orange) CuS and SrS (bluish) to other salts to change colour.
5. Safety advice for paints, solvent-based, oil-based, water-based, acrylic-based, P.V.A. paints and vinyl paints
Harmful if ingested.
Minimize skin content.
Highly flammable, depending on solvent and amount of solid material.
Avoid inhalation of the vapour, and minimize skin contact.
When applying ensure good ventilation.
Dispose of residues as land fill after evaporation of the solvent.
Consult the MSDS for the product selected to learn whether it is a hazardous substance.
Oil-based paints are linseed oil based and considered harmless, but they may be irritating to the eyes and skin.
For years K-6, staff should only carry out clean up of these paints with white spirits or turpentine.
Water-based paints may still contain a small amount of solvent.
6. Safety advice for caustic-based paint strippers
Highly toxic if ingested.
Highly corrosive.
Avoid inhalation of vapour and skin contact.
Wear eye and skin protection when splashes are possible.
When applying ensure good ventilation.
Follow the directions on the label.
Consult the MSDS to learn whether it is a hazardous substance.
7. Safety advice for solvent-based paint strippers.
Harmful if ingested.
Highly flammable.
Avoid inhalation of vapour and skin contact.
It may contain dichloromethane or ethyl methyl ketone, so follow the directions on the label.
Consult the MSDS to learn whether it is a hazardous substance.

19.3.1 Bases in the kitchen and laundry
Bases in the kitchen and laundry, washing powders, di-sodium tetraborate (III)-10-water (borax)
Sodium tetraborate, Borax, sodium tetraborate decahydrate
Hydrolysis of sodium carbonate
Washing soda, Na2CO3.10H2O, Sodium carbonate, Na2CO3
1. Alkaline solutions are used for cleaning greasy dishes and for laundry, e.g. washing soda.
Washing powders usually contain di-sodium tetraborate (III)-10-water (borax) and sodium carbonate and are alkaline in solution.
Baking soda has a basic reaction and can neutralize the acids in fruit or in bee stings.
2. Use borax, sodium tetraborate decahydrate, Na2B4O7.10H2O to clean stains on carpets, neutralize odours of garbage, urine, soured milk, baby clothes, refrigerators, humidifier water.
3. Use soap or detergent solution to clean silver plate, china crocery, hairbrushes and combs, metal coffee pots, chocolate stains, walls and floors, porcelain and aluminium cookware, water spots on glasses and dishes, wine and alcohol stains, laundry, diapers, woollen clothes, shine china crocery, chocolate stains, soften soap, windows.

19.3.3 Metals in the kitchen
Metals in the kitchen, aluminium, iron, zinc, chromium
Aluminium and iron are affected by acids in the kitchen.
Cleaning of zinc and aluminium with alkalis.
Possibility of aluminium in place of iron in foods by displacement.

19.3.2 Bath cleaning
1. Mix equal parts of common salt, borax and kerosene into a paste.
Rub on a dirty bath to remove dirt and grease.
Finish rubbing with a soapy cloth and a dry cloth.
2. Use boric acid to prepare children's clothing flame retardant.

19.3.8 Prepare preserving agents for cut flowers
The bacteria in water will rot the cuts on stems of cut flowers, causing the block of capillaries, a decline in water absorbability and the deficiency in biogenic nutrition, and finally withering up the flowers.
Water with a certain amount of a preservative agent added can prolong the life of cut flowers.
Preservative agents usually contain the following:
1. Nutritious substances: Sucrose and oxime are usually used.
Both serve as source of energy and bring stomas to shut up to weaken transpiration.
2. Bactericide: Silver nitrate, copper (II) sulfate or sodium hypochlorite can be used.
3. Ethylene inhibitor: Silver nitrate or silver thiosulfate is commonly used.
4. Acidified water: The pH value is kept to 3 to 4.
Also, people crush the ends of the stems of cut flowers and put concentrated sugar solution or vodka into the flower vase.
Experiments
1. Use a small quantity of alcohol and water to dissolve 0.1 g of oxime in a large beaker and then pour more water in to dilute he solution to 500 mL (the mass percentage of oxime is about 0.02%).
Add a few drops of dilute sulfuric acid to adjust the pH value of the solution to pH 5 to pH 6.
While stirring, dissolve 0.025 g of silver nitrate (the mass percentage is about 0.005%) and 10 g of sucrose.
After mixing this prepared preservative solution, use it for cut flowers.
2. Test quality of the preserving agent for cut flowers.
Pour 500 mL of tap water into another large beaker.
Put the same number of cut flowers as those in the above experiment in the water.
Under the same conditions make a comparison, every three days, about the number of flowers and the water absorbing quantity.
Pour 500 mL of tap water into another large beaker.
Put the same number of cut flowers in the water.
Under the same conditions, make a comparison, every three days, between the two cases about the number of flowers and the water-absorbing quantity.
3. Some people claim that the best preservative for cut flowers is a solution of 11/2 teaspoons of sucrose in 200 mL of water.
Other people recommend a very dilute solution of household bleach.
4. Dissolve small amounts of ammonium chloride, potassium nitrate, and sodium carbonate or camphor in water.
These substances are supposed to keep flowers from losing their turgidity by stimulating cells and preventing growth of bacteria.
Wilted flowers may revive if the cut stems are placed in a dilute solution of camphor.

19.3.6 Prepare camphor oil
1. Crush camphor cake.
Add salad oil, 5 mL eucalyptus oil, and a few drops of turps.
Put ingredients in a small bottle.
Put bottle in saucepan containing water.
Slowly bring water to boil.
Use camphor oil when cool.

19.3.7 Prepare soap, household soap
1. Add to a tin can half full with water, 2.27 kg dripping (animal fat) free from salt, 0.45 kg resin.
Boil for 30 minutes then add 1 tablespoon borax or kerosene and 0.45 kg caustic soda.
When bubbling stops (from adding the caustic soda) boil for two hours.
Leave in tin for two days then cut into slabs with a tight wire.
BE CAREFUL! Add caustic soda gradually to avoid boiling over!

19.1.3 Perfumes and smells
Perfumes (fragrances) are essential oils usually concentrated in the petals of flowers that may be extracted by liquid fat, ethanol steam distillation and vacuum distillation for more sensitive oils and supercritical solvents, e.g. carbon dioxide.
The underarm smell is a mixture of many "notes", (types of smells) mainly isovaleric acid, and 4-ethyloctanoic acid, the goat smell.
The banana scent is isoamyl acetate.
| Oil of cloves is Eugenol.
Synthetic musk galaxolide.
Methyl mercaptan, "mercaptan", is a smelly sulfur compound put in odourless natural gas to give it a warning smell.
The smell of acetone in the breath is a symptom of diabetes.
Eau de Cologne 4711 contains lemon, orange, bergamot, and rosemary essences.
Garlic odour is formed by enzymes when garlic cells are cut or crushed.
Anti-perspirants are based on aluminium salts that form aluminium hydroxide gel in sweat pores blocking the pore.
Fragrances used in women's toiletries include amber, caramel, citrus, (orange essence), (green mandarin), (bergamot from orange peel), freesia, fuchsia, gardenia, honeysuckle, jasmine, lily of the valley, lily, magnolia, musk (white musk), osmanthus, peony, praline, prickly pear, rose, sandalwood, strawberry (wild strawberry), vanilla, violet petals, wood (white wood).

19.1.2 Lipstick
Lipstick contains an oil-based wax, antioxidant, preservative, perfume, and colour.
The body is made of castor oil and carnauba wax or beeswax.
Lipstick must be thixotropic, i.e. stiff in the tube and stays in the tube when the lipstick is put down on a table, but liquid under pressure when applying the lipstick to the lips.
Carmine, C22H20O13, is the original red colour of lipstick, from the crushed bodies of the cochineal insect, (Coccus cacti).

19.1.1 Hair and hair products
A single hair may support a 80 g weight and wet hair can carry 1/3 of its weight in water.
Women's hair has a growing phase of 6 years and reaches 70-80 cm.
Men's hair has a growing phase of 4 years and reaches 40-50 cm.
The black colour of hair is caused by melanin pigment, but redheaded people also have an iron-based pigment.
Old men sometime produce baby hair, called lanugo.
A change in humidity twists in hair that can be used in novelty "weather houses" to predict changes in the weather.

In hair, the hydrogen bonds within individual helices of keratin, and disulfide bridges between adjacent helices, give strength and elasticity.
Water can disrupt the hydrogen bonds, making the hair limp, but when the hair dries, new hydrogen bonding gives hair the shape of the curler.
Hair straightening treatments, permanent wave, permanent crease solutions give new disulfide bridges between the helices.
Hair contains keratin protein chains in a protein matrix.
Hairstyles depend on the frictional forces between hairs, which can be altered with setting and styling lotions.
This increases the friction between straight hairs that combined with the surface tension that drags hairs together makes combing wet straight hair a difficult task.
However, with very curly hair, as seen in Papua New Guinea and Africa, water relaxes the hair structure and reduced friction between hairs, so the hair can be straightened.
Keratin, C47H77N13O15 is a fibrous protein occurring in hair, wool, feathers, hooves and horns, imbedded in a matrix that makes them strong and elastic.
The proteins contain sulfur and are held together by disulfide bonds.
Sulfides at slightly alkaline pH can split disulfide bonds between keratin molecules.
The solution is buffered with thioglycollic acid then neutralized with hydrogen peroxide so that it sets again with hydrogen sulfide given off.
The hydrogen sulfide causes the strange smell coming from women's hairdressing salons where "permanent waves" are produced.
Hydrogen peroxide bleaches melanin in hair and softens the hair cortex, thus weakening it.

19.1.4 Shampoo
Shampoo, (origin Hindi, 'press', 'kneed'), liquid or cream preparation to be rubbed into hair
Shampoo contain surfactants which lather when added to water, to remove oils and dirt from skin and hair.
Also, positively charged molecules. which are attracted to the hair shaft to make the hair smoother and easier to brush.
Contents of a regular shampoo:
1. Anionic surfactants: Sodium lauryl sulfate, C12H25O4S.Na or C12H25NaO4S, Sodium laureth sulfate, C14H29NaO5S
2. Non-ionic surfactant: Cocamidopropyl betaine, (Lauroylamide propylbetaine), C19H38N2O3
3. Acid buffers to stabilise acidic pH: Sodium citrate C6H5Na3O7 or C6H5O7.3Na or Na3C6H5O7, Citric acid C6H8O7 or (CH2COOH-C(OH)COOH-CH2COOH)
4. Emulsifiers: Sodium xylenesulfonate, C8H11NaO3S, Hydroxypropyl methylcellulose, C56H108O30
5. Parfum (perfume material): Butylphenyl methylpropional, C14H20O, Hexyl cinnamal, (alpha-Hexylcinnamaldehyde), C15H20O, 6. Germicide: Sodium benzoate, C6H5COONa
7. Chelating agent: Tetrasodium EDTA, (Sodium edetate), C10H12N2O8Na4, (NaOOCCH2)2NCH2)2, C10H12N2Na4O8, (Tetrasodium EDTA = Ethylenediaminetetraacetic acid tetrasodium salt)
8. Hair shiner: Panthenol, (DL-Pantothenyl alcohol), C9H19NO4
9. Antistatic agent: Panthenyl ethyl ether, C11H23NO4
10. Fragrance fixer: Benzyl salicyclate (Benzyl 2-hydroxybenzoate, Salicylic acid, benzyl ester), C14H12O3

19.1. Sunscreens and sun-protective clothing
1. Sunburn - After sun tips - take a cool shower - saltwater droplets can magnify UV rays and dehydrate skin - se a beach shower or wet washcloth to remove that salt.
2. After a shower and drying off, moisturize the skin from top to toe.
3. Apply a nourishing lip product to soothe chapped and sunburnt lips.
4. Sun, sea water and chlorine can damage your hair.
Use a lightweight, water-resistant UV defence mist or broad-spectrum product to protect the hair, and apply a leave-in treatment or mask after shampooing.
The facts on sunburn
Symptoms include: 1. Changes in skin colour (pink, red, even purple). 2. Skin feels hot, is painful and swollen. 3. Skin is blistered and peeling.
No matter how mild, sunburn can cause irreversible skin damage.
The long term effects of sunburn can include premature wrinkling and an increased risk of skin cancer, including the potentially deadly melanoma.
Depending on the severity, it can take a day or several weeks for skin to heal after being burned.
Time and patience are the only cures, but medical attention may be required in more serious cases.
Sunburn treatment
Milder sunburns can be treated at home and the following may help skin recover faster:
* Apply cool or cold compresses or bathe burnt skin in cool water.
*. If it is not too painful, apply a moisturizer to help boost the skin's moisture content.
* Avoid using soap as it can irritate the skin.
* Do not pop blisters or pull off peeling skin.
* Keep out of the sun until skin has completely healed.
* Drink plenty of water, because prolonged sun exposure can also lead to dehydration.
* Speak to your pharmacist about products that may help soothe sunburn, Most Australians need sun protection when the UV index is three or above.
For daily sun protection times for your location, use the SunSmart UV Alert at: http: //www.sunsmart.com.au.
1. Overexposure to ultraviolet A (UVA) and ultraviolet B (UVB) can cause skin damage, e.g. sunburn, rashes, premature wrinkling and skin cancer.
Many changes with ageing are the result of damage by too much sun.
A skin tan occurs when the skin produces additional pigment to protect itself against sunburn from ultraviolet rays.
Minimize exposure to the sun between 10 a.m. and 3 p.m, wear a hat and tightly woven clothing, and use maximum protection sunscreens.
2. Sun-protective clothing fabrics have a tight weave and a dark colour.
The garment should have a label listing its Ultraviolet Protection Factor (UPF) value.
The higher the UPF, the more the protection from UV rays, e.g. UPF rating of 20 only allows 1 / 20th of the sun's UV radiation to pass through it.
For children, apply sunscreens with a minimum SPF of 15 about 30 minutes before they go outdoors.
Infants should not be in the sun!
Sunscreens may irritate baby skin and the developing eyes of a baby are vulnerable to sunlight.
3. The best sunscreens block both UVB (UV radiation with wavelength between 315 and 280 nm), which can cause sunburn, and UVA, (UV radiation with wavelength between 380 to 315 nm), which damages the skin without causing sunburn.
The peak sensitivity of the skin is the 290 to 320 nm range that causes sunburn and skin cancer.
Sunscreen inhibits the production of Vitamin D so 15 minutes per day of direct exposure to the sun is needed.
Too much sunbathing is one of the major causes of skin cancer across the world.
An immediate, but short lasting sun tan occurs when the hormone α-melanocyte stimulating hormone is made when the body is exposed to sunlight.
It produces the pigment melanin when pale unoxidized melanin granules in the skin are changed by UV light to the dark brown oxidized form.
Melanin, C18H10N2O4
A lasting sun tan occurs when the amino acid tyrosine produces extra melanin.
4. The higher the sun protection factor, SPF, the more protection a sunscreen offers against UVB, the ultraviolet radiation that causes sunburn.
A sunscreen with SPF 10 blocks 90.0% of UVB, SPF 20 blocks 95.0% of UVB, SPF 30 blocks 96.7% of UVB and SPF 60 blocks 98.3% of UVB.
The SPF indicates how long you can stay in the sun without the skin reddening about 6 hours after exposure.
The exposure needed to produce reddening is called the minimum erythemal dose, MED.
SPF = exposed time for MED in protected skin / exposed time for MED for unprotected skin.
So if you burn in 10 minutes without sunscreen and you apply an SPF 15 sunscreen, be protected from sunburn for 10 × 15 = 150 minutes.
Protection depends on the skin type of the user, amount applied, frequency of reapplication, activities, e.g. swimming, time of day, season
It also depends on and the percentage of UV reflected to scattered by the environment, e.g. snow to sand.
Swimming and perspiration may reduce the SPF value.
No sunscreen product screens out all UVA rays.
Sunscreens with the same SPF numbers may have different ingredients to different combinations of the same ingredients.
5. Test a new sunscreen first to avoid any allergic reaction.
Apply 30 minutes before you go outside and reapply after swimming to activity that causes perspiration.
However, invisible damage and skin ageing can be caused by ultraviolet type A, which does not cause reddening pain.
Normal sunscreen does not block UVA as effectively as UVB.
UVA may cause DNA damage to cells deep within the skin and increasing the risk of malignant melanomas.
So some people recommend purchasing a "broad-spectrum" sunscreen that blocks both UVA and UVB.
Claims of "all day protection" should be ignored an SPF over 30 does not provide significantly better protection.
Sunscreens should be reapplied every 80 minutes to remain effective.
6. Most sunscreens contain either an organic compound that absorbs UVt light, e.g. oxybenzone, C14H12O3, or opaque material to reflect light, e.g. ZnO.
The principal ingredients are usually aromatic molecules conjugated with carbonyl groups that absorbs high energy ultraviolet rays.
Most ingredients do not undergo significant chemical change, so they retain the UV-absorbing potency without significant photodegradation.
The many allowable active ingredients in sun blocks include: p-Aminobenzoic acid (PABA) Avobenzone, Cinoxate, Dioxybenzone, Homosalate
7. Windows filter out more UVB, that causes sunburn, than UVA that cause premature skin ageing and skin cancer.
However, long term exposure through glass can cause damage.
For example, motor vehicle drivers get more skin cancers on the face and upper body on the side nearest the driver door.
8. A so-called "base tan" from limited exposure to natural light or radiation in a tanning salon can reduce the appearance of sunburn.
However, it does not protect against sunburn and may lead to the belief that less or even no sunscreen is needed to protect from UVA and UVB.

19.2.5 Food colouring and ADHD
Food colouring uses chemicals to add colour to processed foods, drinks, and condiments to add colour to food.
Foods with colouring must be are accurately labelled so consumers know what they are eating.
Food colouring dyes are water-soluble powders, granules, or liquids.
Food colouring lakes are not water-soluble and are used in fats and oils.
Synthetic colour additives include FD&C Blue Nos. 1 and 2 and FD&C Green No. 3.
Food colourings from pigments of vegetables, minerals, or animals include beta carotene, grape skin extract, caramel colour, and saffron.
Attention deficit hyperactivity disorder, ADHD, may begin in childhood and cause behaviour problems.
However, there is no conclusive evidence that food colouring causes ADHD.
One study showed that foods containing dyes could increase hyperactive behaviour in 3-, 8- and 9-year-old children given drink mixtures containing:
Sunset yellow (E110), Carmoisine (E122), Artrazine (E102), Ponceau 4R (E124), Quinoline yellow (E104), Allura red (E129).
Experiments
Food colourings are used to tint flowers.
Mix food colouring in warm water and place the flower stems in the solution overnight.
The stems will absorb the colours by morning, revealing intriguing designs in different colours.

19.2.9 Sous vide cooking with a Ziploc bag
A Ziploc bag is a polyethylene plastic bag with a plastic zipper strip along two edges that can be shut by pressing the edges together, and later reopened.
Ziploc bags are used for sandwich bags, waterproof storage, first aid supplies, wet sponges, dirty diapers, marinate meats, store seeds.
Some versions can be used in a microwave oven.

19.2.4 Cooking safety
Dangerous activities
1. Trying to catch a knife when it's falling, especially a professionally sharpened chef's knife that falls off your counter.
2. Throwing water on a grease fire.
3. Using hands to push meat through a meat slicer, instead of using a using guard, or a metal chain glove.
4. Grabbing hot pans.
5. Not wearing nonslip kitchen shoes.
6. Not holding your knife right, which can make for a wobbly / uncontrolled cut.
7. Serving raw food, especially chicken, it is so easy to poison customers with raw meat, check temperatures and when chicken is well done.

Uses of penetrating oil, e.g. WD-40
1. To treat parasitic mites mange, remove toe stuck in the bathtub faucet, remove substances stuck on surfaces, remove oil spots from driveways.
2, Prevent dead insects and mud sticking to bicycles and cars, clean clogged spray paint can nozzles, thread electrical wire to push through conduits.
3. Clean gardening equipment, prevent squeaks in door hinges and new shoes, remove grease from clothing, polish wood furniture, remove crayonmarks.