Food Chemicals: FATS

triesters of glycerol with the fatty acids: hence triglycerides

O-CO-long chainCH2

CH

CH2

O-CO-long chain

O-CO-long chain

water

acid or base

CHOH

CH2OH

CH2OH

+ 3 RCOOH

Fat or triglyceride glycerol fatty acids

FATTY ACIDS (natural ones have even numbers of C’s, formed from acetyl-CoA = CH3CO--- CoA and are cis)

COOH13791215

18

#C’S # DB'S POSITIONS NAME SOURCE

4/6 0 Butyric/caproic Butter8/10 0 Caprylic/capric Coconut12/14/16 0 Lauric/myristic/palmitic Palm18 0 Stearic Beef fat18 1 9(-10) Oleic Olive Oil18 2 9;12 Linoleic Soy Bean18 3 9;12;15 Linolenic Fish/Liver20 0 Arachidic Peanut20 4 5;8;11;14 Arachidonic Fish/Liver22 0 Behenic Canola

(Rapeseed)

COOH13791215

18

Systematic names:

Butyric acid = butanoic acid 4C butaneCaproic acid = hexanoic acid 6C hexaneCapric acid = decanoic acid 10C decaneLauric acid = dodecanoic acid 12C dodecanePalmitic acid = hexadecanoic acid 16C hexadecaneStearic acid = octadecanoic acid 18C octadecaneArachidic = eicosanoic acid 20C eicosaneBehenic = docosanoic acid 22C docosane

DHA = docosahexaenoic acid 22C – 6 C=C (at 4,7,10,13,16,19 positions) - found in fish oils, membranes of eyes, brain

Linoleic acid is essential in our diets (we can make the others)Arachidonic acid: COX enzymes convert to prostaglandins, etc.

Iodine # = g I2 per 100g of oil (a measure of unsaturation)

OIL % SATD % MONO % POLY IODINE #

Coconut 93 6 1 8-10Butter 25-40Palm 57 36 7 37-54Lard 44 46 10 45-70Margarine 80-85Olive 15 73 12 75-95Peanut 21 49 30 85-100CANOLA 7 61 32 ~115Cottonseed 26 22 52 100-117Corn 14 29 57 115-130Fish 120-180Soybean 14 24 62 125-140Safflower10 14 76 130-140Sunflower 11 19 70 130-145Linseed 170-205

All natural fatty acids are all cis: but can be isomerized to trans trans-isomers are higher melting than cis-isomers: solid fats vs. oils

Saturated fats (no double bonds): pack better, higher Mp = SOLIDS

Can increase mp of OIL by HYDROGENATION and/or ISOMERIZATION to get solids = margarine

The more double bonds, THE HIGHER THE IODINE NUMBER a) BUTTER has IN=30, mostly C4-C6-C8 short chain saturated acids: IN varies with the milk source (diet of the cow)b) SOYA OIL has IN=120-140, mostly C18 with 2-3 double bonds: part hydrogenated, part isomerized to get Margarine, IN ~85(NOTE: olive oil also has IN=90, but is all cis and thus is an OIL)

CANOLA OIL used to be mostly C22 but selective plant breeding has produced modern Canola strains that are mostly C18:

7% satd; 61% mono unsaturated; 32% polyunsaturatedNow mostly (91%) C18: C18-1 = Oleic (55%)

C18-2 = Linoleic (26%)C18-3 = Linolenic (10%)

so 0.91 x 26% = 21% Linoleic in Canola

-6 and -3 oils

COOH

1st double bond at C-6 from end = -6

COOH

1st double bond at C-3 from end

6

3

-6 FATTY ACID -Linolenic acid Plant Oils FATTY ACIDLinolenic acid Fish oils

Modern diets are high in -6, about 10x the -3, while old diets were about 1:1

Current theory is that -3 gives lower blood triglyceride levels

PLUS 1g of -3 per day has been shown to give a 20% reduction in heart-related deaths

Lack of -3 leads to heart disease, thrombosis, atherosclerosis

Modern Canola has about 11% -3 while decreasing Erucic acid C22-1(13-14) to <1% Erucic acid was prevalent in old rapeseed oil and has been implicated in heart lesions

As a matter of interest see: Monsanto vs. Schmeiser – a well-documented court case where Monsanto sued Schmeiser for patent infringement when he saved seeds from a Round-up Ready (a genetically modified Canola strain) Canola that had blown into his field from neighbouring areas

Trans-fats (US and CAN require labelling)

Modern margarine has some cis-bonds isomerized to trans to increase ‘solidity’: Hard margarine ~12% trans-fatsSoft margarine ~5% trans-fatsBecel 0% trans-fat but still ~12% saturated fat

Current hypothesis: trans fats increase LDL’s a few % = a small increase in risk of heart attack

Ban on use of trans-fats in restaurants comes into effect in BC in September ’09 (already adopted, then abandoned in Calgary)

DISADVANTAGES of unsaturated fats: easier to oxidise

-CH=CH-CH-CH=CH- -CH=CH-CH-CH=CH- | •

H

Allylic hydrogen is easily oxidised to a free radical which further reacts with oxygen to cleave the chain and produce SMELLY short chain fatty acids (under-arm sweat and rancid butter smell)

An ANTIOXIDANT (usually ArOH) can supply a H• back to this free radical and reform the fat, before it has had time to react with oxygen: the resulting phenoxy radical ArO• is stable.

NOTE: Butylated hydroxytoluene (BHT) is 2-t-butyl-4-methylphenol and it is commonly added to cereals for the same reasons (next page)

Hence need to protect fats with antioxidants:

BHT BHA VITAMIN E butylated- butylated- -tocopherolhydroxytoluene hydroxyanisole allowed at 0.01-0.02% too expensive for food

Note: in these the ArO• is highly crowded which makes it less reactive

OH OH

OMe

O

HO

FLAVINOIDS

O

OH

OH

OH

HOeg. epicatechin are found in green and black teas, red wines and also have antioxidant properties: reduced heart disease?

ANTHOCYANINS

R2, R5, R7 virtually always OHand other R groups may be OH

Powerful anti-oxidants foundas pigments in berries, flowers, vegetables, outer skins: blueberries, blood oranges, jalapenopeppers, purple onions, red apple skins, many others

OILS: Vegetable oil production 80-100 Mtons/y mostly asSoy, Palm, Canola (about ~20% each) plus minor amounts of coconut and peanut oils

Soft margarine has 80% fat 16% waterLow fat soft margarine has 40%fat 56% water!!!

Fats don’t dissolve in water, so have to emulsify them

COO- Na+

COO-

COO--OOC

-OOC

-OOC

-OOC

-OOC COO-

COO-

A piece of dirt (grease): hydrocarbon tails embed in grease; water surrounds the -COO- groups and the grease ‘dissolves’”

For fats can use phospholipids: eg. Lethicin (egg yolks)

C17H31COO-CH2

| C17H31COO-CH

| - + CH2OPO3CH2CH2NMe3

greasy end binds fat ionic end binds water

Remember bile acids transport fatsthru the intestine for use

Cholic acid:

Similarly mono- or diglycerides bind fats to sugars:

C17H31COO-CH2

| CH-OH

| CH2-OH

greasy end binds fat this H-bonds to sugar -OH’s

so used in shortenings, cakes and cookies: can get up to 40% sugar in a cake without it being ‘crunchy’; fats make cookies more ‘crumbly’

FAT SUBSTITUTESSome are ‘modified’ starches, have the texture of fat but 4 kcal/g rather than 9 kcal/g

OLESTRA

O

OH

H OH

HH

O

CH2OH

H

HOO

H

HO

HO

H

CH2

HO

H

CH2OH

each -OH of sucrose is converted to a-OCO(CH2)6,7,8CH3

the resulting molecule cannot pass through the intestine, so is not absorbed: because it is so ‘greasy’ it can lubricate the intestines too much so ‘anal leakage’ can occur carrying with it some fat soluble vitamins

Natural Waxes are long chain acid / long chain alcohol esters: CH3(CH2)24/26COO(CH2)29/31CH3 = beeswax

Carnauba wax (used for car polish and coatings on ‘no-mess’ candies like Smarties, M+M’s) contains some pendant HO~~~~COOH that polymerize and give it its hardness

CANNOT DIGEST THESE

Jojoba oil is an unsaturated ‘wax’ that is not metabolised: under study as a frying oil

CH3(CH2)7CH=CH(CH2)mCOO(CH2)nCH=CH(CH2)7CH3

m = 9,11; n=10,12 chain lengths vary

Used in cosmetics as a moisturizer and in many skin and hair care products; also under investigation as a diesel oil

Cholesterol, Fats and Oils, Salt and Calories in Foods (per 100g)

Food Cholesterol Oil or Fat (grams) Salt Calmg Satur Mono-un Poly-un mg

Beef, raw 91 2.7 2.7 0.5 54 152Chicken 85 1.3 1.5 1.0 70 165Cheese (cheddar) 105 21.1 9.4 0.9 615 400Corn oil 0 12.7 24.2 58.7 0 884Eggs, whole 548 3.4 4.5 1.4 142 143Hot dog, all beef 51 12.7 14.8 1.2 1026 296Milk, whole 14 2.3 1.1 0.1 40 60Olive oil 0 13.5 73.7 8.4 0 884Margarine (Becel) 0 10.0 30.0 40.0 700 700Butter 215 50.5 23.4 3.0 576 720Tuna (canned) 63 0.2 0.1 0.2 338 116Salmon (canned) 35 1.0 1.8 2.7 487 140Peanut butter (unsalted) 0 9.7 23.3 15.2 17* 588Yogurt (plain, skim milk) 6 1.0 0.4 0.04 77 56