School Science Lessons
Chemistry
2026-03-07
Chemistry Experiments, F
Chemistry, F
Contents
Fabrics, (burning tests)
Fabrics, (household)
Face cream emulsion
Face shields
Fahrenheit scale
Faraday's first law
Farnesene
Farnesol
Fats
Febrifugine
Fehling's solution
Feldspars
Fenchol
Fenchone
Fentanyl
Fermentation
Fermium
Ferric compounds
Ferricyanides
Ferrites
Ferritin
Ferrous compounds
Fertilizers for plants
Fertility of soil
Ferulic acid
Feruloylputrescine
Fexofenadine
Fibre in diet
Fibre glass resin
Fibro, Asbestos
Fibrous proteins
Ficin
Ficine
Fieldwork, Geology
"Fight or fright hormone", Epinephrine
"Fill water", (Swimming pools)
Fillers in washing powders
Filter funnels
Filters, (swimming pools)
Filtration
Fingerprints, (ninhydrin
Fingerprints, (iodine)
Fining wine
Fipronil
Fire Safety
Firming agents
FIRST AID, Poisons
Fisetin
Fish oils
Fish oils, Trans fats
Fisetin
Trimethylamine Fish smell
Fisher projection formula, D-, L- glyceraldehyde
Fission, Uranium
Fixed oils
Fixing insects solutions
Fizzy drinks
Flame retardants
Flame tests, (metals)
Flame tests, (salts)
Flammable
Flash point
Flavan and flavone
Flavanols, (Flavan-3-ols)
Flavonol glycosides
Flavanones
Flavones
Flavonoids
Flavour
Flavoxanthin
Flaxseed oil
Flocculation, (muddy water)
Flocculent
Froth flotation of heavy minerals
Flour
Flowers, Distil essences
Flubendazole
Fluorescein
Fluorescence
Fluorspars
Fluorine
Fluorophores
Flux, soldering
femtomole, 1 femtomole = 10-15 moles
Foam, (Polymer)
Foaming agents, washing powders
Foams
Folic acid
Food
Fool's gold, Pyrite
Forgery
Formaldehyde
Formic acid
Formononetin
Formula, Group formula
Forskolin
Forsythiaside
Fracking
Fractions, (crude oil)
Fractional distillation of crude oil
Francium
Frangulanine
Fraxin
Free element metals
"Freons", CFCs
Friedel-Crafts reaction
Friedelin
Froth flotation
Fructose
Fruit salts
Fuchsine
Fucosteroll
Fucoxanthin
Fuels
Fuller's earth
Fumaric acid
Fume cupboards, fume hoods
Fumigants
Functional groups
Fungicides
Functional groups of organic chemistry
Furanocoumarins phytotoxic
Furfural
Furfurol
Falcarinol, C17H24O
Falcarinol, carotatoxin, panaxynol, long-chain fatty alcohol, irritant, causes contact dermatitus, pesticide, fungicide
It occurs in carrots (Daucus carota), red ginseng (Panax ginseng), and in ivy Hedera.
Farnesene
Farnesene, C15H24, sesquiterpene (six isomers), acylic sesquiterpene, alpha-farnesene, flavour and fragrance agent, green apple odour,
oxidized to cause fruit skin scald, in oil or perilla, anti-viral.
It occurs in perilla (Perilla frutescens), gardenia aroma, pheromone to deter aphisds.
Isomers occur in apple, orange, grapefruit, mandarin and lime peel, grape, pear ginger, nutmeg, basil.
Alpha- and beta-farnesene, occurs in citronella oil, from Cymbopogon.
Alpha-farnesene occurs in coating of apple and pears, used as flavouring ingredient.
Trans-beta-farnese is a hydrocarbon lipid molecule.
Farnesol
Farnesol, C15H26O, sesquiterpene, acyclic sesquiterpene alcohol, a farnesan.
Colourless liquid, insoluble in water, miscible with oils, extracted from the oils of plants, flavouring, miticide.
It occurs in many essential oils, citronella, neroli, cyclamen, tuberose, bitter orange, ginger, jasmine, hops, beets, juniper, citronella, lemon grass, tuberose,
rose, musk, balsam of Peru, tolu balsam.
It occurs in apricot, orange peel, grapefruit juice, cloves, ginger, thyme, basil, papaya, anise seed.
It occurs in sweet acacia (needle bush), flowers used for floral essence perfumes.
Farnesol is a colourless liquid extracted from oils of plants such as citronella neroli, and tuberose and is then used in perfumery.
Farnesol, hydrophobic, enhances perfumes, occurs in citronella, chamomile oil, oil of neroli petate, cyclamen, lemon grass, tuberose, rose, musk,
and balsam, frankincense, biofuel.
Fats
Fats in food
Burn carbohydrates, fats and proteins: 9.9.1
Classification of fats: 3.9.2
Cooking fats: 19.1.3
Digestibility of fats: 9.2.4
Fatty acids
Heating fats: 3.9.7
Hydrogenation
Prepare soap: 12.4.0
Steam distillation to measure water and fat content of food: 10.3.11
Tests for fats and oils: 9.3.11
Tests for unsaturated fats: 9.3.33.1
Tests for unsaturated fats, bromine water test: 9.3.33.2
Fats in food
3.9.2 Classification of fats
3.9.3 Composition of edible oils
3.9.4 Fats in animals and plants
3.9.5 Fatty acids
3.9.6 Fatty acids, ω-3 and ω-6 fatty acids
3.9.7 Heat fats
3.9.8 Hydrogenation, cis-trans fatty acids
3.9.9 Rancidity of fats
3.9.10 Trans fats, Omega-fatty acids
Fenchol
Fenchol, Fenchyl alcohol, (1,3,3-trimethyl-2-norbornanol), C10H18O, terpene, isomer of Borneol, flavouring ingredient with bitter lime-like flavour.
It is used in perfumes, monoterpenoid, isomer of borneol, colourless or white solid, occurs widely, enantiopure (1R)-endo-(+)-fenchol can be oxidized to fenchone.
It occurs in volatile oils of Aster, in Basil (Ocimum basilicum), and in Fennel (Foeniculum vulgare).
Fenchone
Fenchone, C10H16O, monoterpene ketone, colourless oily liquid.
It occurs in the alcoholic drink absinthe, bitter taste of wild Fennel, in oil of Fennel, (Foeniculum vulgare).
Fentanyl
Fentanyl, C22H28N2O, monocarboxylic acid amide, narcotic analgesic, strong and rapid opioid analgesic
An intravenous anaesthetic, it is used to treat chronic cancer pain or in anesthesia.
It has high potential for drug abuse then dependence, adulterant in illicit drugs, e.g. heroin. commonly involved in opioid overdose deaths.
Fermentation
Alcoholic fermentation with yeast 9.1.1
Butyric acid fermentation with a potato 9.1.2
Carbon dioxide and fermentation for brewing 3.8.0
Glucose fermentation 9.1.4
Fermentation 4.1.9 (Safety)
Safety in the microbiology laboratory 4.1.12
Triple scale wine hydrometer 10.2.8
Fermium, Fm
Fermium, Table of the Elements
Fermium, RSC
Fermium, Fm, (Enrico Fermi, 1901-1954, Italy), radioactive actinide element, produced by bombarding plutonium with neutrons, called Fermium in 1952
Fexofenadine
Fexofenadine, C32H39NO4, anti-histamine compound, which is used to treat allergic symptoms.
It occurs in Bergamottin
Bergamottin, (C21H22O4), in grapefruit interferes with the action of drugs, e.g. Atorvastatin, ("Lipitor"), C33H35FN2O5, to lower bad cholesterol, by blocking the action of enzymes
in the small intestine to increase the amount of drug absorbed and the action of fexofenadine.
Ficin
Ficus protease; Higueroxyl delabarre, CH2FI2N, sulfhydryl proteinase, from ficus latex,
It is used in alcoholic beverages, beer chillproofing agent, meat tenderiser, dough conditioner, rennet substitute, precooked cereals.
Ficain (or ficin) is an enzyme from fig latex, an endopeptidase, used for differentiating many blood group antigens.
Fire Safety
Action in case of fire, evacuation 3.5.2
Action in case of fire, equipment 3.5.3
Face shields
Fire blankets blankets
Fire extinguisher
Fire safety and fire equipment 3.5.0
Fireproof, Asbestos 35.2.4
Fireproof, cloth, paper, wood 3.5.10
Fireproof, Talc 35.3.13
Flammable
Fire extinguisher
Fire extinguishers
Fire extinguisher, dry chemical powder, paper, wood, textile, oil, liquid and electrical fires, 2.5 kg, 4.5 kg
Fire extinguisher, soda acid fire extinguisher 3.3.1H
Fire extinguisher cart, water stream impulse 17.7.5
Feruloylputrescine
Feruloylputrescine, C14H20N2O3, (originally called Subaphylline), a methoxycinnamamide.
It occurs in leaves and juice of grapefruit (Citrus paradisi), and in (Salsola subaphylla).
Flammable
FLAM, designates something that can readily burn or catch fire.
Flammable aerosols: 2.3
Flammable gases: 3.5.11
Flammable liquids: 3.5.12
Flammable solids: 2.7
Flammable substances: 3.5.13
Storing flammable liquids 3.7.5
1. The word "flammable" means "easily set on fire".
You can use "non-flammable", but in chemistry do not use "inflammable".
Flammability, explosion, limits outer limits for the ratio of fuel to air within which the mixture will burn.
The mishandling of flammable solvents has probably caused fires and personal injuries in chemical laboratories, e.g. burning of loose long hair.
Staff and students must have securely fixed and contained hair by tying back the hair or using caps or hair nets.
Flammable solvents become more difficult to ignite as their boiling points rise, so use the highest boiling point solvent possible.
Do not use water baths to heat volatile flammable solvents.
Solvents should only be used by staff with students after assessment of the risks, including flammability, toxicity, and possible allergic reactions.
2. Carbon disulfide has a greater flammability than ether and forms more dense vapours, with a low ignition temperature < 100 oC.
Carbon disulfide is not permitted in schools.
3. Diethyl ether evaporates readily to form a heavy vapour in air, which can travel along the bench or floor in an air current.
Diethyl ether is not permitted in schools.
4. Hydrogen forms violently explosive mixtures with air in almost any proportions and spontaneously combusts at concentrations greater than 4% in air.
Use this gas for demonstration purposes only in extremely small quantities or use soap bubble techniques.
5. Natural gas forms explosive mixtures with air, so turn off heaters, Bunsen burners, and equipment using natural gas and other flammable gases, e.g. acetylene.
6. Methylated spirit, ethanol and hydrocarbon solvents, e.g. petroleum spirit, hexane, pose the greatest risk in schools.
Mixtures of air with any of these materials are highly flammable, and ignition of vapour is usually followed by a fire in or around the solvent container.
Flavour
Flavourings, (Cooking)
The major flavour components are:
* Ethyl 3-hydroxyhexanoate
* Linalool
* Limonene
* Phellandrene
* Terpineol
Flavoxanthin
Flavoxanthin, C40H56O3 a xanthophyll from buttercups, a yellow carotenoid pigment, E161A.
It occurs in (Taraxacum officinale), (Ranunculus acris), and Oregon 'grape', (Berberis aquifolium).
Flocculent
A flocculent is usually a precipitate in cloud-like tufts, flocs.
In bacteriology, flocculation refers to the formation of floccules, (agglutinated bacteria), in a precipitin test, especially for antigens of Salmonella.
In mining, flocculation refers to coagulation of ore particles to form flocs and to remove excess water.
Flour
Flour treatment agents, food additives: 19.1.13
Experiments
Prepare flour glue: 9.1.1
Prepare self-leavened flour, "self-raising flour": 19.1.9, (See: 7.)
Prepare wallpaper paste: 9.1.3
Use flour to clean brass: 19.1.9, (See: 8.)
Use flour to make glue: 19.1.9, (See: 9.)
Use flour to make papier-mâché: 19.1.9, (See: 10.)
Use flour to make play dough: 19.1.9, (See: 11.)
Fluorescence, fluorescein
See diagram: Fluorescein.
Fluorescein, C20H12O5, Solvent Yellow 94, Resorcinolphthalein, yellow solid or orange-red crystals that have green-yellow fluorescence by reflected light.
It is insoluble in water, but soluble in dilute aqueous bases.
Very dilute alkaline solutions of fluorescein show strong green-yellow fluorescence by reflected light.
Fluorescein (lactone form) is a xanthene dye that is highly fluorescent.
It is used by detectives to detect traces of blood, and s an indicator in silver nitrate titrations.
It is a fluorescent dye, a xanthene dye, a gamma-lactone, a polyphenol, and is used to examine corneal injuries.
Fluorescent minerals absorb ultraviolet light and emit longer wavelength visible light, e.g. scheelite.
Fluorescence is luminescence that does not persist when the exciting cause is removed, e.g. a fluorescent light.
The rapid emission of light at longer wavelengths than that which is absorbed, e.g. adsorption of ultraviolet light can yield blue fluorescence.
Certain excited atoms emit a photon of lower energy than the incident photon that caused the transition.
If the process takes place rapidly, < 10-7 seconds, it is called fluorescence.
Experiment
Use a 1 500 alcoholic solution of eosin to demonstrate fluorescence
6.6.3 Chlorophyll fluorescence
28.6.2 Critical angle in ripple tank, refraction tank, aquarium (fluorescein)
16.3.27 Fluorescein
7.22 Fluorescence staining of cells and tissues
38.8.3 Fluorescent lamp (Electronics)
16.3.28 Fluorescent liquids
12.6.6 Fluorescent whitening agents in washing powders
14.26 Fluorophores, (Fluorescent chemical cmpounds)
Luminescence
Phosphorescence
Terbium, Tb, Phosphorescence
Flubendazole
Flubendazole, C16H12FN3O3, is used in human and veterinary medicine for nematode infections.
Fluorine, F
See Fluorine, RSC
Fluorine, Table of the Elements
Fluorine, F, (Latin fluere to flow), very reactive, halogen, pale yellow gas
Fluorine is a naturally occurring element, in fluorspar, CaF2.
It is a yellow-green gas, strong, sharp odour (like pool chlorine), combines with hydrogen to form hydrogen fluoride.
Fluorine gas can cause irritation, muscle spasms, harm the lungs and heart and cause death.
It is a non-metal yellow-green poisonous gas at room temperature and pressure.
Fluorine is the most reactive corrosive and electronegative of all elements.
It never occurs as a free gas, but it occurs in many silicate minerals and the mineral fluorite, CaF2.
Fluorine is the most electronegative non-metallic element, strong oxidizing agent.
Fluorine combines with carbon to form inert polymers, e.g. Teflon coated frying pans, and form low friction fluorocarbon polymers, e.g. PYFE.
'Freon'
'Freon' is the brand name for the refrigerant, CCl2F2, Dichlorodifluoromethane (R-12), a colorless gas usually sold under the brand name "Freon-12".
In Australia. the Pharmacist only medicine "NeutraFluor 5000 Plus", Colgate, contains sodium fluoride 11.05 mg/g.
However, some natural water sources already contain the fluoride ion.
The enamel of teeth are formed from the crystalline mineral hydroxyapatite, Ca10(PO4)6(OH)2.
Fluorine is used to make CFCs, chlorofluorocarbons, freon, that damages the ozone layer.
Fluorine compounds are added to toothpaste and drinking water, e.g. tin (II) fluoride, sodium monofluorophosphate (MFP), sodium fluoride and amine fluorides.
In some countries, sodium fluoride is added to drinking water to improve the hardness of tooth enamel apatite of children's teeth.
However, some people believe that sodium fluoride is too reactive to be put into drinking water and it may cause discoloration of teeth.
In Australia solid sodium silicofluoride is added to drinking water in some places.
However, some natural water sources already contain the fluoride ion.
The enamel of teeth are formed from the crystalline mineral hydroxyapatite, Ca10(PO4)6(OH)2.
Boron trifluoride, BF3, colourless, pungent, toxic gas, white smoke in moist air
Emitters of fluoride are metal cleaning operations, glass and enamel manufacturing and glazing, toothpaste, and fluoride enhanced water.
These emissions may be to the soil, water, or air.
Fluorourcil, C4H3FN2O2, 5-fluorourcil, cancer drug, Toxic by all routes, Not permitted in schools
Fluoride compounds all contain fluorine.
Fluorine is found in nature as part of the mineral fluorspar.
Fluoride (fluorido), F-, monodentate ligand
SPADNS fluoride reagent solution, 500 mL, (HO)2(C10H3(SO3Na)2N=N(C6H4SO3Na, indicator for zirconium and thorium
Fluorides
Potassium fluoride, KF, corrodes glass
Calcium fluoride, calcium fluorite, fluospar, Harmful if ingested
Cryolite: 35.2.28
Elements in the Earth's crust: 34.5.1
Fluoridated toothpaste 9.3.13.4
Fluorspar: 35.2.32
12.19.5.0 Freons, CFCs, chlorofluorocarbons, "Freons"
Hydrofluoric acid, HF: 12.19.7.0
16.14.2 PFOA, perfluorooctanoic acid, CF3(CF2)6COOH, TeflonTM
16.14.3 PFOS, perfluorooctane sulfonate, perfluorooctanesulfonic acid, C8HF17O3S
Prepare hydrogen fluoride, HF 12.19.7.1
Prepare silicon tetrafluoride, SiF4 12.19.7.2
Sodium fluoride
14.26 Fluorophores
Fluorophores are fluorescent chemical compounds.
(1.) 1-chloro-9,10-bis(phenyl ethynyl) anthracene emits green-yellow light in 30-minute high-intensity Cyalume sticks
(2.) 2-chloro-9,10-bis(phenyl ethynyl) anthracene emits green light in 12-hour low-intensity Cyalume sticks.
(3.) 1,8-dichloro-9,10-bis(phenyl ethynyl) anthracene emits yellow light in Cyalume sticks.
(4.) 9,10-diphenylanthracene (DPA), C26H18, emits blue light in light sticks, yellow powder.
(5.) 1-chloro-9,10-diphenyl anthracene (1-chloro(DPA)) emits blue-green light.
(6.) 2-chloro-9,10-diphenyl anthracene (2-chloro(DPA)) emits blue-green light.
(7.) 9,10-bis(phenyl ethynyl) anthracene (BPEA), C30H18 emits "ghostly" green light in light sticks.
(8.) 2,4-di-tert-butylphenyl 1,4,5,8-tetracarboxynaphthalene diamide emits deep red light, but with DPA emits white or hot-pink light.
(9.) Fluorescein isothionate, FITC, emits green light.
(10.) Rhodomine tetramethyl isothionate, TRITC, "Rhodominr Red-X", emits orange light.
(11.) Hydroxycoumarin, emits blue light.
(12.) Cyanine dyes, Cy2 cyanine, Cy3 indocarbocyanine, Cy5 indodicarbocyanine.
(13.) Biological fluorphores, e.g. green fluorescent protein, GFP, occurs from a jellyfish.
(14) Quantum dot nanocrystals.
Folic acid
Folic acid, C19H19N7O6, "folate", Vitamin B9, is seen as odourless orange-yellow needles, which darkens and char.
It is an N-acyl-amino acid, a form of the water-soluble vitamin B9, which is essential for nucleotide biosynthesis.
It is an important component of diet during phases of rapid cell division, e.g. infancy and pregnancy, and protects against cancer.
It occurs in green vegetables, avocado, and citrus fruits.
Folic acid derivative, tetrahydrofolic acid, C19H23N7O6, essential for synthesis of DNA and RNA, and purines, pyrimidines, and methionine.
Folic acid may help reduce the risk of neural tube defects in babies and foods fortified with folic acid have been used by pregnant women.
However, recent research suggests that such fortified food increases the risk of cancer.
Food
Food and nutrition (cooking), Websites
Food: 19.3.0
Food acids, acids in foods: 19.1.5
Food additives: 19.1.0
Food allergies and intolerances, "hyperactive": 19.2.0
Food colouring liquids and detergents: 16.3.4
Food colouring: 19.2.5
Food preservation: 19.2.0
Food tests, tests for food: 9.3.0
Food used in plant respiration: 9.1.7
Colloids in food: 19.3.3
Glycaemic index (GI): 9.1.10
Electrophoresis, food dyes, marking pen ink: 19.4.2
Elements in food: 19.3.4
Different kinds of food: 2.34 (Primary)
Digestion of food: 5.20 (Primary)
Heat of combustion, bomb calorimeter, energy values of food: 22.5.6
Micro-organisms and food spoilage: 4.3.10
Prepare food, using microbiology: 4.4.0
Water content of food: 19.2.16
19.1.5 Food acids, acids in foods
Ethanoic acid, acetic acid, vinegar
Benzoic acid, in cranberries, prunes and plums
Butyric acid, betanoic acid, in decomposition of butter, rancid butter
Citric acid, in citrus fruits, lemon, orange, cocoa, pepper, rhubarb
Tannic acid in tea
Tartaric acid in grapes, pineapples, potatoes, carrots.
Formaldehyde, CH2O
Formaldehyde solution, methanal, formalin, Toxic by all routes, Corrosive (use < 2 mL only)
Formaldehyde, Solution < 1%, Not hazardous
Formalin, 40% solution of formaldehyde in water, forms toxic fumes
Formalin, paraform, methylene glycol, methyl aldehyde
Formalin, 40% solution of formaldehyde in water
Formaldehyde may contain 10-15% ethanol to prevent polymerization
Formaldehyde with hydrochloric acid may form carcinogenic bis(chloromethyl) ether
FAA, (formalin, acetic acid, alcohol), biology fixative, for plant material: 2.8
Formal saline, para formaldehyde: 2.10
Formalin, biology fixative: 4.4
Formaldehyde, formalin, biology fixative for animal material: 2.9
Formaldehyde, Indoor air pollution: 18.6.4
Prepare formaldehyde-acetic acid alcohol, FAA solution: 2.8
Prepare urea-formaldehyde resin: 3.3.12
Prepare formaldehyde-resorcinol resin: 3.3.6
Urea-formaldehyde, (urea-methanal), resin, thermoset plastic: 3.8.11
Formaldehyde solution
Formaldehyde solution, HCHO, CH2O (aq), gas readily soluble in water, methanal (+10% methanol), formalin 40% methanal solution
Do NOT mix with HCl, because carcinogenic bis(chloromethyl) ether may form, so do NOT dispose formaldehyde and HCl in the same sink.
ACS reagent, 37 wt % in H2O, contains 10-15% methanol as stabilizer, (to prevent polymerization).
Formaldehyde, (methanal), is highly poisonous and probably carcinogenic and should be handled with extreme care.
Formaldehyde is transported and stored as a concentrated aqueous solution called "formalin".
When a bottle of formaldehyde is opened, a large amount of gas may be released, but do NOT inhale the formaldehyde gas.
Do experiments with concentrated formaldehyde solutions in a fume cupboard.
However, dilute formaldehyde solutions produce little formaldehyde and can be safely handled in the open laboratory.
Preserve biological specimens in a solution of 50% ethanol and 50% water, instead of formaldehyde solution.
Do not mix hydrochloric acid and formaldehyde solution, because highly carcinogenic bis(chloromethyl) ether may form.
Do NOT store bottles of hydrochloric acid near formaldehyde, because the reaction might occur in the air.
Do NOT dispose of formaldehyde solutions and hydrochloric acid in the same sink system.
Formic acid, CH2O2
Formic acid, CH2O2, HCOOH, methanoic acid, Toxic by all routes, Corrosive, lung irritant
Formic acid, (in insect stings, ants)
Formic acid, Solution < 2%, Not hazardous
Methanoic acid, ionization reaction 16.2.7
Formic acid
Formic acid, HCOOH, methanoic acid, conc 46 M, hydrogen carboxylic acid, in ants and stinging nettles, most simple carboxylic acid
Formic acid is highly poisonous and should be treated with care.
It is highly volatile and the vapour should NOT be inhaled.
Formic acid, the only simple aliphatic carboxylic acid to possess reducing properties, because of the presence of a (-CHO) component in the molecular structure.
Formic acid is both an aldehyde and a carboxylic acid.
HCOOH + H2O <--> H3O+ + HCOO-, Ka = 1.8 × 10-4
Forskolin, C22H34O7, a cyclic ketone, anti-hypertensive, anti-HIV agent
It occurs in (Coleus forskohlii), Apis and in (Plectranthus barbatus).
Forskolin occurs in the roots of the Indian coleus (Coleus forskohlii), a folk medicine used to treat cough, asthma symptoms, insomnia, and skin diseases.
Forsythiaside A, C29H36O15
Forsythiaside A, is a hydroxycinnamic acid
Forsythia, Oleaceae
Forsythia is used to treat swelling of small air passages in the lung, inflammation and fever.
However, the mechanism is not known.
Francium, Fr
Francium , Table of the Elements
Francium, RSC
Francium, Fr (France), radioactive, heaviest alkali metal element, from uranium ore decay.
It was the last "natural" element, discovered by Marguerite Percy, France, in 1939
Francium exists only as compounds, very rare, disintegration product of actinium, MP 300.15 K.
Friedelin
Friedelin, C30H50O, friedelan-3-one, a pentacyclic triterpenoid, cyclic terpene ketone, a major triterpenoid
It is a non-narcotic analgesic drug, antipyreticm, anti-inflammatory diuretic, antipyretic.
It occurs in many plants, Aesculus, Cannabis, Citrus, Diospyros, Ceratopetalum, algae, peat, and coal.
It is the main triterpenoid in cork, Quercus suber.
Fuchsine, C20H19N3.HCl
Fuchsine, C20H19N3.HCl, (fuchsin), rosaniline hydrochloride, triphenylmethane dyestuff, magenta dye, dark green crystals
In water forms a purple red solution, (the colour of flowers of Fuchsia, Onagraceae),
It is used as a disinfectant for skin infections and to stain bacteria.
Basic fuchsine has variable contents including rosaniline and similar compounds, and is used in Schiff's reagent test for aldehydes.
Acid fuchsine is mixture of basic fuchsine + sulfonic groups to decolorize it.
Fuchsine (fuchsin) is sold as:
1. Basic Fuchsin, C19H17N3.HCl, dye, Basic Parafuchsin, Basic Red 9, Magenta O, Parafuchsin hydrochloride, Pararosaniline hydrochloride
2. Basic Fuchsin, C20H20ClN3, for microscopy, indicator (pH 1.0-3.1), Basic Violet 14, Fuchsin basic, Magenta, Rosaniline
3. Acid Fuchsin, C20H17N3Na2O9S3, for tissue staining, Acid Violet 19, Fuchsin S, Fuchsin acid, RubineS
Fuchsine, Fuchsin, rosaniline hydrochloride, magenta dye, brilliant red aniline dye from coal tar.
Acid fuchsin, acid-base indicator: 1.00
Calberla's pollen stain: 7.11
Magenta colour: 27.8.0
Fucosterol, C29H48O
Fucosterol, Isofucosterol, Delta 5-avenasterol, phytosterol, associated with phytosterolemia an inborn error of metabolism, in brown algae in coconut
Fucoxanthin
The accessory pigment fucoxanthin is the brown pigment in brown algae and diatoms.
Fuels
A fuel cell is a device with a cathode and anode, which converts a fuel directly into electricity without burning.
The simplest case is hydrogen gas bubbled over a porous sintered nickel anode in alkali solution and oxygen is bubbled over a similar cathode separated by a porous membrane.
An electric current is produced in an external circuit.
A fuel cell is like a battery, except that fuels, e.g. methanol, rather than metals are consumed, and the reaction is not reversible.
Fuel cell: 7.4.30
Biofuels
Biogas, (Safety in school science)
Recommended maximum quantity of fuel to be stored in a schools:
1. Oil and grease 40 L, clean oil contains irritants, used oil contains contaminants, use gloves and eye protection with grease
2. Petroleum, Petrol (gasoline), highly flammable
3. Diesel 20 L, toxic fumes, irritates skin and eyes
4. Two stroke petrol mix, toxic fumes, irritates
5. Kerosene, 5 L, toxic fumes, irritates skin and eyes
Calorific value of fuel, heat transfer
22.2.1 Calorie
Biofuels
A biofuel is a fuel from renewable plant or animal material, (feedstocks), unlike fossil fuels, e.g. coal, natural gas, petroleum.
Solid biofuels include grass and wood, which can release heat when burnt.
First generation biofuels are produced from mostly plant-based starch, sugars and oils.
Sugar from sugarcane, sorghum and maize can be fermented into ethanol, which can be used as a motor fuel
Oil extracted from oil-seed crops, e.g. canola, soybean, oil palm, coconut, restaurant waste and animal-based tallow can be converted into biodiesel.
Second generation biofuels use lower-value biomass residues, from forestry, agriculture, municipal solid wastes or dedicated energy crops.
Biomass can be turned into biofuels through different processes.
Biochemical processes produce fermentable sugars from cellulose, as in paper.
Pyrolysis, in which organic material is decomposed at high temperatures without oxygen.
Algal oil production from large scale open ponds or closed algal photobioreactors.
Biogas, produced by wastes in an anaerobic digester, consists mainly of methane and carbon dioxide
Biomass is very resistant to breaking down, because the plant has to be pretreated to break open its fibre structure and access the sugars in cell walls.
Enzymes can be used to convert cellulose into glucose.
Questions
1. What is the the environmental impacts of growing the initial crop for the lower-value biomass residues?
2. Is more energy produced and taken ou than put in to growing the crop and producting the fuel?
3. What are the the greenhouse gas reduction benefits of the fuel, which takes the place of the fossil fuels?
Functional groups
Functional group See diagram 16.0.0
1. Alcohols, 2. Aldehydes, 3. Amines and Amides, 4. Carboxylic acids, 5. Cyclic compounds, 6. Esters, 7. Ethers, 8. Halogens (Alkyl Halides)
9. Ketones R = alkyl group
1. Alcohols, R-OH, -OH hydroxyl, Prefix hydroxy-, Suffix -ol (-OH alcohol) (alkanol, alkyl alcohol)
Multiple -OH groups suffixes -diol, -triol, -tetraol, e.g ethylene glycol = ethane-1, 2-diol, CH2OHCH2OH
2. Aldehyde, R-CH=O, Prefix formyl-, Suffix -al
Cyclic aldehydes, Prefix formyl-, Suffix -carbaldehyde, attached to benzene benzaldehyde
3. Amines and Amides
Amines R-NH2, Prefix amino-, Suffix -amine
Primary amine, R1NH2, Secondary amine, R1NHR2, Tertiary amine, R1NR2R3, e.g trimethylamine
Amide, RCONH2, (amine + acid), No prefix, Suffix -oic, amide, e.g, acetamide = ethanamide, CH3CONH2
R-C(=O)NR'R', Prefix carbamoyl, NH2CO, Suffix -carboxamide, RCONH2)
4. Carboxylic acids, RCOOH, Prefix carboxy-, Suffix -oic acid, Multiple dicarboxylic acid, tricarboxylic acid
6. Esters, RCOOR', Prefix R-oxycarbonyl-, Suffix -alkyl, -oate, e.g. methyl formate = methyl ethanoate, HCOOCH3, (but "ethyl acetate", keeping old name)
7. Ethers, ROR', (Alcohol names), -ether, Prefix -oxy-, e.g, dimethyl ether = methoxymethane, CH3OCH3
8. Halogens, (Alkyl halides), R-X, Prefixes fluoro-, bromo-, chloro-, dichloro-, trichloro-, iodo-, e.g chloroform, trichloromethane, CHCl3
Haloalkanes, halogenalkanes, alkyl halides, e.g. Acyl chloride, acid chloride, RCOCl, functional group -CO-Cl
Prefix halo-, formyl-, Suffix -oyl halide, e.g. chlorofluorocarbons, CFCs
9. Ketones, RCOR', keto-, -one, e.g. acetone = propan-2-one, C=OH2, Prefix oxo-, Suffix -one
Furfural
Furfural, C5H4O2, (2-Furaldehyde), furan-2-carbaldehyde, acute toxic, irritant, health hazard, a heterocyclic aldehyde,
A colourless or red-brown oily liquid, penetrating odour, denser than water, soluble in water, toxic by ingestion, skin absorption or inhalation, almond smell.
It thermosets easily and resists corrosion.
It occurs in wheat bran, maize bran, vanilla, cinnamon and is a Maillard reaction product.
Also, it occurs in the peels of ripe Carica papaya (Papaya) and Ananas comosus (Pineapple) fruits show high yield of furfural.
Furfurol
Furfurol, C5H6O2, furfuryl alcohol, (2-Furanmethanol), primary alcohol, acute toxic, irritant, health hazard, clear colourless liquid, denser than water
It irritates skin, eyes and mucous membranes, toxic by ingestion and skin contact
It occurs in (Perilla frutescens), and in (Zea mays).
Febrifugine, (C16H19N3O3), Quinoline Alkaloid
Febrifugine, quinazoline derivative, (3,4-Dihydro-4-quinazolone derivative), antimalarial.
It occurs in (Dicrroa febrifuga), (Hydrangea febrifuga), and in (Hydrangea macrophylla).
See diagram: Febrifugine.
Ficine, (C20H19NO4), Unclassified Alkaloid
Ficine, dihydroxyflavone, N-alkylpyrrolidine, occurs in wild fig (Ficus pantoniana).
See diagram: Ficine.
Frangulanine, (C28H44N4O4), Peptide and Cyclopeptide Alkaloid
Frangulanine, Ceanothamine A, frangula bark used as a purgative, weak antibiotic, occurs in Ramnus, Waltheria, New Jersey tea (Ceanothus americanus).
See diagram: Frangulanine.
16.3.3 Friedel-Crafts reaction
The reaction substitutes a hydrogen atom in an arene ring of a halogen alkane by an organic group, R, using aluminium chloride catalyst.
RCl + AlCl3 --> R+ + AlCl4-
For example, benzene with chloromethane forms methyl benzene.
benzene + CH3+ --> benzene-CH3 + H+
CH3Cl +AlCl3 --> CH3+ +AlCl4-
3.9.2 Classification of fats
1. Saponification value from hydrolysis of a fats into component fatty acids, as their anions or soaps, and glycerol.
Saponification value = number of milligrams of potassium hydroxide to saponify one gram of fat (or oil).
It is a measure of the average chain length, molecular mass of the fatty acids.
2. Fat and saponification value:
Coconut oil 250-260, Butter 245-255, Lard (pig fat) 193-200, Peanut oil 185-195, Linseed oil, 189-196. 3.
Iodine value measures the number of double bonds in the fat.
Iodine reacts with the double bond.
Iodine value is the number of grams of iodine that react with 100 g of fat or oil.
Fats with low iodine values are saturated.
Fats with high iodine values are polyunsaturated.
Fat and iodine value: Coconut oil 8-10, Butter 26-45, Lard 46-66, Peanut oil 83-98, Linseed oil 170-204. 3.
3. Acid value measures how much glycerides in the fat or oil have been decomposed to free acid.
This is regulated by food standards codes.
4. Peroxide value measures the oxygen taken up by the oil to form peroxides and is a measure of the freshness of the oil.
This regulated by food standards codes.
5. Oxygen uptake.
If polyunsaturated fats are incubated at 60 oC, they gain weight from oxygen uptake.
3.9.3 Composition of edible oils
Table 1.1.1
| Type of Oil |
% Monounsaturated fat |
% Polyunsaturated fat |
% Saturated fat |
| Canola oil |
58.9 |
29.6 |
7.1 |
Coconut oil
|
5.8 |
1.8 |
86.5 |
Corn oil
|
12.7 |
58.7 |
24.2 |
| Flaxseed oil |
22 |
74 |
4 |
| Grape seed oil |
16.1 |
69.9 |
8.1 |
| Olive oil |
77 |
8.4 |
13.5 |
| Palm oil |
37 |
9.3 |
49.3 |
| Palm kernel oil |
11.4 |
1.6 |
81.5 |
| Peanut oil |
46.2 |
32 |
16.9 |
| Safflower oil |
12.6 |
73.4 |
9.6 |
| Sesame oil |
39.7 |
41.7 |
14.2 |
| Soybean oil |
23.3 |
57.9 |
14.4 |
3.9.4 Fats in animals and plants
1. Fats and oils, animal fat (tallow, suet, dripping is fat from beef cattle), (lard is pig fat), soap is made from animal fat and hydroxide
Suet fat
Suet is solid fat around kidneys of cattle and sheep, to be melted to form tallow.
Suet pudding is made of suet + flour, wrapped in a cloth, then boiled.
Tallow fat
Tallow is hard fat formed from rendering suet.
IIt contains stearin, palmitin, olein, and is used for candles and soap.
2. Fats and oils are used to store, transport and utilize the fatty acids that an organism requires for its metabolic processes.
Energy storage in animals: fat 38 kj / g, carbohydrates 17 kj / g, protein 23 kj / g.
Fats store water and when metabolized in the body to produce energy, they also produce water, e.g. fatty hump of the camel.
Plants, fungi, yeasts and bacteria, can synthesize both fats and their component fatty acids.
Animals can synthesize most of their fatty acid needs, but they prefer to ingest plant foods and modify them to their own needs.
Only plants can synthesize linoleic and linolenic acids, but animals can increase the chain length and further increase unsaturation, e.g. fish oils, that are rich in unsaturated acids.
Saturated fatty acids are predominantly present in fats that are solid at room temperature, e.g. milk, butter and animal fats.
Saturated fats may raise the level of "bad" cholesterol leading to hardening of the arteries, high blood pressure, heart disease and strokes.
Animals produce mainly saturated fats, because their fats also have a structural support function and must not be too fluid.
Some animals can maintain a high temperature through internal heating, insulation and behaviour.
Unsaturated fatty acids may be mono-unsaturated or polyunsaturated.
Mono-unsaturated fatty acids, e.g. oleic acid, are found in most animal and plant fats and oils, especially olive oil.
Unsaturated fatty acids occur mainly in oils.
Most fats and oils contain a mixture of saturated and unsaturated fatty acids, but in widely varying proportions.
An intake of fat in the diet is essential as some fatty acids are required for important functions in the body.
Fat soluble vitamins A, D, E and K must also be provided by food containing fat.
A fat free diet is not only difficult to prepare, but is also very unpalatable.
3. The so-called "bad cholesterol" is the LDL (low density lipoprotein) cholesterol used to build body cells
Excess cholesterol can form plaque on the walls of arteries to the heart and brain, causing atherosclerosis.
The "good cholesterol" is HDL (high density lipoprotein) cholesterol produced in the liver and intestines that removes excess cholesterol from atherosclerosis plaques.
It may protect from heart attack.
Electrophoresis is used to separate the LDL fraction of total cholesterol to measure the HDL and LDL levels and determine the risk factors for coronary heart disease.
4. Polyunsaturated fatty acids, e.g. linoleic acid, linolenic acid, are found mainly in vegetable oils.
Polyunsaturated fats are essential to animals as building blocks and for controlling the cholesterol content of the blood.
Plants produce mainly unsaturated oils that allow them to withstand extremes of temperature, because their fats or oils are fluid at low temperatures.
Polyunsaturated fats lower "bad" cholesterol, but also lower "good" cholesterol.
Polyunsaturated fats are found in margarine, vegetable oils and seed oils.
Some research claims that polyunsaturated fats may be are oxidized into "free radicals" that contribute to the development of some cancers and accelerate ageing.
5. Mono-unsaturated fats are the "good" fats and should make up most of the fats in a diet, up to about 30% of a diet.
Saturated fat in the diet can raise the level of blood cholesterol to increase the risk of heart disease from atherosclerosis, fatty plaques on the walls of blood vessels.
Unsaturated fat can form free radicals by lipid peroxidation, leading to cancer and accelerated ageing.
So both saturated and unsaturated fat can have health hazards!
3.9.5 Fatty acids
3.9.6 Fatty acids, ω-3 and ω-6 fatty acids
1. A fatty acid is carboxylic acid, which has an hydrocarbon chain and a terminal carboxyl group, e.g. oleic acid, CH3(CH2)7CH=CH(CH2)7COOH.
The group of saturated and unsaturated aliphatic carboxylic acids are called fatty acids and are found as esters in fats and oils.
Lower carbon fatty acids are corrosive liquids with strong odour and are soluble in water.
Higher carbon fatty acids are oily liquids with unpleasant smell and are only slightly soluble in water.
Fatty acids from C10 onwards are usually solids and are insoluble in water.
Fatty acid are aliphatic acids with chain lengths 6 to 30, and occur in all fats.
Saturated fatty acids, e.g. propionic acid, CH3CH2CO2H, and monounsaturated fatty acids, e.g. oleic acid, C18H34O2, are synthesized by the body.
Polyunsaturated fatty acids, e.g. linolenic acid, C18H30O2, must be in the diet.
Oleic acid has one double bond: CH3−(CH2)7−CH=CH−(CH2)7−COOH
2. Fats, oils and some waxes are the naturally occurring esters of long, straight chain carboxylic acids.
These esters are the materials from which soaps are made.
At room temperature, fats are solid or semi-solid and oils are liquids.
alcohol + organic acid --> ester + water glycerol + fatty acid --> fats or oils + water
All fats form from glycerol, glycerine, propan-1,2,3-triol, CH2OHCHOHCH2OH.
3. The fatty acid part of the fat differs as follows:
* in the length of the chain, which controls the molecular mass, and
* in the number and position of the double bonds, unsaturation.
4. The three main groups of fatty acids are as follows:
* Saturated fatty acids, e.g. stearic acid,
* Straight chain unsaturated fatty acids, e.g. oleic acid,
* Polyunsaturated fatty acids, e.g. linoleic acid.
5. The normal saturated fatty acids have the general formula, CH3(CH2)nCOOH,
where n is usually an even number from 2 to 24, e.g. stearic acid (n=16) lauric acid (n=10).
Milk contains short chain fatty acids, n < 10.
6. The building block for fatty acids is the acetate ion, CH3COO -,
The most important unsaturated fatty acids have 18 carbon atoms with one double bond in the middle of the chain, called mono-unsaturated fatty acids.
Polyunsaturated fatty acids have more double bonds between the middle double bond and the carboxyl group, COOH.
Atoms can rotate about single bonds, but not about double bonds, so two arrangements are possible called "cis" and "trans".
Most double bonds in natural fats and oils are cis, e.g. oleic acid in olive oil.
Fatty acids with the cis double bond do not pack together easily, so have a low melting point of double bond containing material, i.e. oils.
Substances made up of shorter chains also melt at lower temperatures.
Chemists describe polyunsaturated fatty acids as having more than one cis-methylene interrupted double bond.
7. The poly unsaturated fatty acids linoleic acid, linolenic acid and arachidonic acids are essential fatty acids in the diet to prevent, atheroma,
("hardening of the arteries"), and synthesize prostaglandins.
Saturated fatty acids with no double bonds are linked to the development of atheroma.
Fatty acids in plants occur as esters of glycerol or other hydroxy compound, or amides of long chain amines, e.g sphingenine.
Fatty acids have trivial and systemic names and the molecule may be saturated (no double bonds), or unsaturated (one or more double bonds).
The products called "natural oils" are not necessarily unsaturated fats.
8. Fatty acids are open chain aliphatic monocarboxylic acids derived from, or in esterified form in an animal or vegetable fat, oil or wax.
Natural fatty acids usually have an unbranched chain of 4 to 28 carbons that may be saturated or unsaturated.
All acyclic aliphatic carboxylic acids may be called fatty acids.
Fatty acids list:
Arachidic acid, C20H40O2, in seed oils, in peanut (Arachis hypogaea)
Arachidonic acid, C20H32O2
Behenic acid, Docosanoic acid. C22H44O2
Chaulmoorgric acid, C18H32O2, in Chaulmoogra (Hydnocarpus wightiana)
Decanoic acid, Capric acid, C10H20O2, in chilli (Capsicum species)
Erucic acid, C22H42O2, in nasturtium (Tropaeolum majus)
Hexanoic acid, Caproic acid, C6H12O2, CH3(CH2)4COOH
Octanoic acid, Caprylic acid, C8H16O2
Hexanoic acid, Caproic acid
Dodecanoic acid, C12H24O2, in coconut (Cocos nucifera)
Linoleic acid, C18H32O2, in borage (Borago officinalis)
Linolenic acid, C18H30O2, in perilla (Perilla frutescens var. crispa).
Myristic acid,Tetradecanoic acid, C14H28O2, in orris (Iris florentina)
Oleic acid, C18H34O2, C8H17CH=CH(CH2)7COOH, in Chinese date (Zizyphus jujuba)
Palmitic acid, Hexadecanoic acid, C16H32O2, in abelmosk (Abelmoschus moschatus)
Palmitoleic acid, C16H30O2, in coconut (Cocos nucifera)
Petroselenic acid, C20H40O2, in parsley (Petroselinum crispum)
Ricinoleic acid, C20H40O2, in golden shower tree (Cassia fistula)
Stearic acid, C18H36O2, CH3(CH2)16COOH, in coconut (Cocos nucifera)
Vaccenic acid, C18H34O2, in milkweed (Asclepias syriaca)
3.9.6 Fatty acids, ω-3 and ω-6 fatty acids
The ω-3 fatty acids is a family of polyunsaturated fatty acids.
The parent ω-3-α-linolenic acid (ALA) is obtained from the diet and is polyunsaturated with 8 carbon atoms and 3 double bonds.
The long chain ω-3 fatty acids eicosapentaenoic acid, EPA, and docosahexaenoic acid, DHA, can be synthesized from dietary ALA,
but in seems that EPA and DHA should be obtained from the diet containing oily fish and fish oil, as well as fortified bread and fruit juice.
ALA, EPA and DHA are important role for structural membrane lipids, in nerve tissue and the retina beside a wide range of functions in cells and tissues.
3.9.7 Heat fats
1. Smoke point is the temperature at which a fat breaks down into visible gaseous products and thin wisps of bluish smoke begin to rise from the surface.
Smoke point, smoking point, falls with the continued use for cooking, because the oil or fat decomposes and the free fatty acids have a lower smoke point.
So the higher the initial smoke point, the longer the fat is usable before it starts to smoke.
Smoke point of an oil or fat is an important piece of information for consumers and should be listed on food labels.
2. Flash point is the higher temperature when fat bursts of flame start.
3. Ignition temperature, is the higher temperature at which the entire surface of the frying medium becomes covered with flame.
4. P/S ratio is the ratio of polyunsaturated fatty acids to the saturated fatty acids present.
In western diets the ratio is about 0.6 and increasing it to 1.0 may reduce the risk of atherosclerosis and coronary heart disease.
Heating may not change the P/S ratio of polyunsaturated oils, but it causes formation of oxidized compounds, which tend to destroy vitamin E content and make oils unpalatable.
Changes in the peroxide value of oils after heating reveal how heating oxidizes oils.
5. Smoke point and P/S ratio, approximate values
* Safflower oil: smoke point: 246 oC, P/S ratio: 6.0
* Sunflower oil: smoke point: 229 oC, P/S ratio: 4.7
* Maize oil: smoke point: 229 oC, P/S ratio: 3.1
* Peanut oil: smoke point: 246 oC, P/S ratio: 1.9
* Soybean oil: smoke point: 256 oC, P/S ratio: 3.7
* Olive oil: smoke point: 204 oC, P/S ratio: 0.5
3.9.8 Hydrogenation, cis-trans fatty acids
Hydrogenation 3[CH2O(CO)(CH2)7CH==CH(CH2)7CH3] + 3H2 --> 3[CH2O(CO)(CH2)16CH]
glyceryl trioleate + hydrogen (nickel catalyst) + heat --> glyceryl tristearate
Hydrogenation means to add hydrogen to a molecule.
Unsaturated fats can be saturated by adding hydrogen to the double bonds with a nickel catalyst.
Hydrogenation converts a substance with the properties of a liquid vegetable oil into a substance with the properties of a solid animal fat.
For example, linoleic and oleic acids turn into stearic acid.
The manufacturing process may cause some hydrogenation of unsaturated fatty acids.
Processed oils such as shortenings may contain a high proportion of fats changed by hydrogenation.
The cis fatty acids and the trans fatty acids
See diagram 16.1.1, Cis-trans isomers of alkenes
In nature, most unsaturated fatty acids are cis fatty acids, i.e. the hydrogen atoms are on the same side of the double carbon bond.
In trans fatty acids the two hydrogen atoms are on opposite sides of the double bond.
Trans double bonds can occur in nature as the result of fermentation in grazing animals, so people eat them in the form of meat and dairy products.
Trans double bonds are also formed during the hydrogenation of vegetable or fish oils.
French fries (fried potato chips) donuts, and other snack foods are high in trans fatty acids.
Manufacturers may hydrogenate polyunsaturated oils to help foods stay fresh or to obtain a solid fat product, e.g. margarine.
Trans fatty acids, i.e. hydrogenated fats, tend to raise total blood cholesterol levels, and raise LDL bad cholesterol and lower HDL good cholesterol.
In some countries, governments have required fast food companies to commit to reducing trans fats in their cooking and listing trans fat content on labels.
Some fast food companies have claimed that consumers do not like the taste of products if all trans fats are eliminated.
However, apparently, if only a small proportion of trans fats are used, taste is not a problem.
In other countries, trans fats in cooking have been banned altogether by legislation.
3.9.9 Rancidity of fats
Oxygen in the air oxidizes unsaturated fats adjacent to the double bond to produce smaller easily evaporated volatile compounds with a rancid smell.
Most of the fatty acids in butter are C16 -C18, but shorter chain fatty acids are also present.
The acid from rancid butter is 1,3-butadiene: CH2=CH-CH=CH2, a butane with two double bonds, bivinyl butyric acid: C3H7COOH.
Cheeses made from milk with more short chain fatty acids have a stronger smell.
Margarine rarely becomes rancid, because the longer chain fatty acids must first be broken before the short chain, rancid smelling compounds form.
Purchased fats and oils have added antioxidants to prevent rancid compounds from forming.
The same short chain acids in rancid butter are present in human perspiration.
3.9.10 Trans fats, Omega-fatty acids
1. Trans fats are trans isomer (E-isomer) fatty acids.
Fatty acids, together with glycerine, are the building blocks of all fats and oils.
Trans fatty acids are unsaturated but, unlike the "good" unsaturated fatty acids found in fish and vegetable oils, behave similarly to saturated fats in the body
and have similar health issues.
Trans fats can be found naturally in meat and milk from certain animals and as a product of fats and oils altered by industrial processes, such as hydrogenation.
2. Hydrogenation is widely used to solidify liquid vegetable oils to make products such as margarine and shortenings and involves adding hydrogen to the oils.
Trans fats are not formed through deep frying food in vegetable oils.
However, manufactured fats such as margarine spreads, fats used in deep frying and fats used in pastry dough, are likely to contain some trans fats,
because they improve the firmness of the product and the products are less likely to be damaged by oxidation, or heat.
Trans fats make cooking oils more stable.
3. Some fats are good for us and can help reduce the "bad" type of cholesterol that causes a lot of health problems.
These good fats include polyunsaturated, monounsaturated fats, omega-3 fatty acids, omega-6 fatty acids or omega-9 fatty acids.
Both trans fats and saturated fats increases the level of "bad" cholesterol, with trans fats also decreasing the level of "good" cholesterol.
This can cause a number of serious health problems.
4. Studies have shown that Australians consume relatively low amounts of trans fatty acids compared with people in other countries.
However, the amount of saturated fats consumed by Australians is of greater concern so the amount of total fat and the amount of saturated fat
must be declared on all food labels.
The amount of trans fat in food must be declared on the label if a nutrition claim is made about cholesterol, polyunsaturated, monounsaturated fats,
omega-3 fatty acids, omega-6 fatty acids or omega-9 fatty acids.
5. Omega-fatty acids
Omega-3 fatty acids cannot be manufactured in the body.
The omega-3 fatty acids group have the first double bond between the third and fourth carbon atoms counting from the right, i.e. from the methyl group.
Omega-3 fatty acids, C60H92O6, N-3 polyunsaturated fatty acid, first unsaturated bond in the third position from the omega carbon,
(the carbon atom of the methyl group at the end of the hydrocarbon chain), e.g. Linolenic acid, α-linolenic acid, C18H30O2,
CH3(CH2)CH=CH(CH2)CH=CH(CH2)CH=CH(CH2)7COOH.
Omega-3 fatty acids may reduce serum triglycerides, prevent insulin resistance, improve lipid profile, prolong bleeding times, reduce platelet counts,
and decrease platelet adhesiveness, e.g. Alpha-linoleic acid, C18H30O2, in seed oils, (rapeseed), and e.g. Eicosapenaenoic acid, C20H30O2, in cod liver oil.
Omega-6 fatty acids,C38H64O4, N-3 polyunsaturated fatty acid, first unsaturated bond in the sixth position from the omega carbon,
e.g. Linolenic acid, C18H32O2, in grapeseed oil.
Omega-9 fatty acids, avocado oil is 70% omega-9 fatty acid, e.g. Oleic acid, C18H34O2 in olive oil and
macadamia oil, Erucic acid
6. Fish oil is a dietary source of omega-3 fatty acids to improve muscle activity and cell growth.
Fish oil contains two omega-3 fatty acids, docosahexaenoic acid, (DHA), C22H32O2, and eicosapentaenoic, (EPA), C20H30O2.
A diet rich in eicosapentaenoic acid lowers serum lipid concentration, reduces incidence of cardiovascular disorders, prevents platelet aggregation.
Fish oils can be in the diet by consuming salmon, mackerel, mussels, and oysters.