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7 Antioxidant

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Page 1: 7 Antioxidant

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The shelf life of food products:

Microbial spoilage

Browning reaction

Oxidative degradation

Lipid oxidation:

Development of off-flavors and odors

Changes in texture (reaction of lipid oxidation products

with proteins)

Loss of nutritive value (vitamins, AA, EFA)

Development of diseases

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II. ANTIOXIDANTS

Retard the lipid oxidation reaction

Are used to stabilize fats and oils, high fat foods, cereals, product containing small amount of lipids

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III. DEFINITION

According to Food and Drug Administration

Substances used to preserve foods by retarding deterioration, rancidity, or discoloration due to oxidation

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IV. LIPID OXIDATION

Oxidation of highly unsaturated fats resulting in polymeric end products

Oxidation of moderately unsaturated fats resulting in rancidity, reversion, and other type of off-flavors and odors

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V. MECHANISM OF LIPID PEROXIDATION

Unsaturated Fats

Free Radicals

Hydroperoxides

Oxidation of pigments,

flavors, vitamins

Breakdown products (including rancid off-

flavor compounds) such as ketone,

aldehyd, alcohols, hydrocarbons, acids,

epoxides

Polymerization (Dark color)

(Possibly toxic)

Insolubilization of proteins

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VI. CLASSIFICATION

Based on function, antioxidants are classified as:1. Primary or chain breaking antioxidants2. Synergist or secondary antioxidants

Primary antioxidants terminate the free radical chain reaction by acting as hydrogen or electron donors to free radicals, resulting in the formation of more stable products

Synergist antioxidants: oxygen scavengers, chelators, regenerating the primary antioxidants, providing acidic medium to improve the stability of primary antioxidants

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VII. PRIMARY ANTIOXIDANTS

Phenols: gallates, hydroquinone, trihydroxybutyrophenone, nordihydroquairetic acid

‘Hindered’ Phenols: BHA, BHT, TBHQ, tocopherols, gum guaiac, ionox series

Miscellaneous primary antioxidants: ethoxyquin, anoxomer, trolox C

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VIII. SYNERGIST ANTIOXIDANTS

OXYGEN SCAVENGERS: react with free oxygen and can remove it in closed system

Examples: ascorbic acid, ascorbyl palmitate, sulfites, erythrobates

CHELATING AGENTS: are not antioxidants but they are highly effective as synergists with both primary antioxidants and also oxygen scavengers

Form complex with prooxidant metals like iron and copper

Examples: EDTA, citric acid, and phosphates

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SECONDARY ANTIOXIDANTS: decompose the lipid peroxides into stable end products

Examples: thiodipropionic acid, dilauryl esters, distearyl esters

MISCELLANEOUS ANTIOXIDANTS: nitrites, amino acids, spice extracts, flavonoids, vitamin A, carotene, tea extracts

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IX. SOME NATURALLY OCCURING ANTIOXIDANTS

Amino acids

Beta carotene

Lecithins

Vitamin E

Vitamin C

Soy protein hydrolysate

Vanillin

Saponins

Phenolic acids

Phytic acid

Rosmarinic acid

Spice extract

Tannins

Flavonoids

Uric acid

Nordihydroguairetic acid

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X. ANTIOXIDANTS PERMITTED FOR USE IN FOOD

L-ascorbic acid, Na, Ca salts

Ascirbyl palmitate and stearate

Butylated hydroxyanisole

Butylated hydroxytoluene

Citric acid, citrates

Erythorbic acid and Na erythorbate (not in EEC)

Ethoxyquin

EDTA, Ca disodium salt

Propyl, octyl, dodecyl gallates

Glycine

Gum guaiac

Ionox 100 (2,6-di-ter-butyl-4-hydroxymethylphenol)

Lecithins

Polyphosphates

Tartaric acid

Tertiary butyl hydroquinone (not in EEC)

Trihydro xy butyrophenone

Thiuodipropionic acid, dilauryl and distearyl esters

Tocopherols

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XI. SAFETY REQUIREMENTS

Soluble in fats

Impart no foreign color, odor, and flavor

Effective for at least one year

Heat stable

Safety conditions:

LD50 must not less than 1000 mg/kg body weight

Should not have any significant effect on the growth of experimental animals in long studies at a level 100 times the level proposed for human consumption

Approval of antioxidant for food use also requires extensive toxicological studies including mutagenic, teratogenic, and carcinogenic studies

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A. Phenols

B. Hindered Phenols

C. Miscel laneous Primary Antioxidants

XII. PRIMARY ANTIOXIDANTS14

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A. PHENOL

a. Gallates (PG, OG, DG)

b. Hydroquinone (HQ)

c. Trihydroxy butyrophenone (THBP)

d. Nordihydroguairetic acid (NDGA)

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a. Gallates

Comprise the propyl (PG), octyl (OG), and dodecyl(DG) esters of gallic acid (3,4,5-trihydroxy benzoic acid)

PG is the most effective and widely used in animal fats, vegetable oils, spices, meat products, and snacks

PG

Melting point 148C, unsuitable for frying oil

Used in combination with BHA, BHT

Sparingly soluble in oil, and soluble in water

PG chelates iron, discoloration, used in combination with citric acid

OG and DG, soluble in oil

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Propyl Gallate18

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Octyl Gallate19

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Dodecyl Gallate20

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ADI 0-0.2 mg/kg bw

OG and DG: adverse effect on reproduction

70% PG is absorbed in gastrointestinal tract, hydrolyzed to alcohol (Krebs cycle) and gallic acid (secreted in urine)

Acute toxicity:

PG LD50 3600-3800 mg/kg bw

OG LD50 4700 mg/kg bw

DG LD50 6500 mg/kg bw

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b. Hydroquinone (HQ)

High level of toxicity

LD 50 less than 1000 mg/kg bw

Considered as harmful and deleterious substances for addition to food

At present, used as stabilizer in polymers

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Hydroquinone23

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c. Trihydroxy Butyrophenone (THBP)

As GRAS by FDA for addition for foods and food packaging materials

THBP is only used in food packaging material

Sparingly soluble in water and soluble in oil

Produces light tan and brown color in the presence of organic metal salts

LD50 3200-6400 mg/kg bw

No adverse effects

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Trihydroxy Butyrophenone25

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d. Nordihydroguairetic Acid (NDGA)

Occurs naturally and commercially synthesized

Effective in oils, fats, and fat containing foods

Removed from the list of GRAS compounds due to its toxicity at high dose levels

No longer used as a food antioxidant in many countries

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Nordihydroguairetic Acid27

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B. HINDERED PHENOLS

a. Butylated Hydroxyanisole (BHA)

b. Butylated Hydroxytoluene (BHT)

c. Tertiary Butyl Hydroquinone (TBHQ)

d. Tocopherols

e. Gum guaiac

f. Ionox series

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a. Butylated Hydroxyanisole (BHA)

Used in fats, oils, fat-containing foods, confectionery. Essential oils, food coating materials, waxes

A mixture of two isomers: 2-BHA and 3-BHA

Soluble in oil and insoluble in water

ADI 0-0.5 mg/kg bw

BHA is readily absorbed in gastrointestinal tracts, metabolized, and completely excreted

No evidence of tissue accumulation

LD 50 2200-5000 mg/kg bw

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BHA30

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b. Butylated Hydroxytoluene (BHT)

The most extensively used antioxidants in food industries

Used in low fat food products, fish products, packaging materials

Widely used in combination with BHA, PG, and citric acid

Soluble in fats and insoluble in water, steam volatile

ADI 0 – 0.125 mg/kg bw

LD 50 in rats 1700-1970 mg/kg bw

In high level has toxic and mutagenic effect

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BHT32

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BHT33

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c. Tertiary Butyl Hydroquinone (TBHQ)

Moderately soluble in fats and slightly soluble in water

Used for the stabilization of fats and oils, confectionery, fried foods

Regarded as the best antioxidant for frying oil and fried products

Not permitted in Japan and EEC

ADI 0-0.2 mg/kg bw

Does not form complex with iron and copper

Rapidly absorbed and nearly 80% is excreted in the urine

LD50 700-1000 mg/kg bw

Not teratogenic and slightly mutagenic at level dose

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TBHQ35

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TBHQ36

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d. Tocopherols

Synthetic products are tocopherol and tocopheryl acetate

Major lipid soluble antioxidant

ADI 0.15-2 mg/kg bw

LD50 is not known

High level: hypervitaminosis E

Show inhibitory action against carcinogens

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Tocopherol38

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e. Gum guaiac

From wood of Guajacum officinale

Commercial gum guaiac consists of and guaiconic acid (20%), guairetic acid (10%), and guaiac yellow (15%)

An effective antioxidant but no longer used due to availability and undesirable color

LD50 >5000 mg/kg

No adverse effect

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Guaiac gum40

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f. Ionox series

Consists of Ionox 100, Ionox 220, Ionox 312, and Ionox 330

Derivatives of BHT

Ionox 100 is approved for use in food products

Ionox 330 is appoved for incorporation into food packaging materials

Ionox 100 is completely absorbed, rapidly metabolized, and quantatively eliminated

Ionox 100: LD50 7 g/kg bw

Ionox 330: LD50 >5000 mg/kg bw

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Ionox 22042

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Ionox 10043

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C. MISCELLANEOUS PRIMARY ANTIOXIDANTS

a. Ethoxyquin

b. Anoxomer

c. Trolox-C

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a. Ethoxyquin

Effective antioxidant for feed to stabilize carotenoids, fish meals, and fish oils

Readily undergoes oxidation to form a stable free radical ethoxyquin nitroxide which is more effective antioxidant than ethoxyquin

ADI 0-0.06 mg/kg bw

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Ethoxyquin46

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b. Anoxomer

Synthetic phenolic polymer

A condensation product of divinyl benzene, hydroxyanisole, TBHQ, and ter-butyl ohenol

Highly effective in frying oils and fried products

ADI 0-8 mg/kg bw

Very poorly absorbed and metabolized because of large molecular size

No adverse effects

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Anoxomer48

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c. Trolox C

A synthetic derivative of alpha tocopherol

Resemble alpha tocopherol structurally

Two to four times the antioxidant activity of BHA and BHT, more actove than tocopherol, PG, and ascorbyl palmitate

Colorless, tasteless, sparingly soluble in oils

Not being used commercially at present

LD50 1630 mg/kg bw

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A . O x y g e n S c a v e n g e r s

B . C h e l a t i n g A g e n t s

C . S e c o n d a r y A n t i o x i d a n t s

D . M i s c e l l a n e ou s A n t i o x i d a n t s

XIII. SYNERGISTIC/SECONDARY

ANTIOXODANTS50

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a . S u l f i t e s

b . A s c o r b i c A c i d a n d S o d i u m A s c o r b a t e

c . A s c o r b y l P a l m i t a t e

d . E r y t h o r b i c A c i d a n d S o d i u m E r y t h o r b a t e

A. OXYGEN SCAVENGER51

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a. Sulfites

Represent a group of compounds comprising SO2, Na2SO3, sodium metabisulfite (Na2S2O5), and sodium bisulfite (NaHSO3)

Antimicrobial and antioxidant, prevent enzymatic browning and preserve freshness

ADI 0 -0.7 mg/kg

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Sulfite53

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b. Ascorbic Acid and Sodium Ascorbate

L-ascorbic acid or vitamin C and sodium ascorbate are used as oxygen scavengers also as synergist in a wide variety of food products

White, odorless, soluble in water and insoluble in fats

Undergoes oxidation to form dehydroascorbic acid

ADI not limited

LD 50 >5000 mg/kg bw

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Ascorbic acid55

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c. Ascorbyl palmitate

Ester of ascorbic acid and palmitic acid

Highly effective in frying fats, oils, and fried products

Ascorbyl palmitate is better than BHA or BHT

In combination with other antioxidants it improves the shelf life of vegetable oils

ADI 0-1.25 mg/kg bw

LD50 25 g/kg bw

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Ascorbyl palmitate57

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d. Erythorbic Acid and Sodium Erythorbate

D isomer of ascorbic acid

No vitamin C activity and does not occur naturally

Effective in the stabilization of nitrite or nitrate-cured meat products, dehydrated fruit and vegetable products

As synergist for tocopherols in fats and oils

In combination with citric acid, is an effective alternative to use of sulfites in frozen seafood, vegetables, and fruits

More rapidly oxidized as compared to ascorbic acid

Highly soluble in water

Not permitted in EEC

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Erythorbic acid59

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Sodium Erythorbate60

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a. Polyphoshpates

b. EDTA

c. Citr ic Acid

d. Citrate Esters

e. Phytic Acid

f . Lecithin

B. CHELATING AGENTS61

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a. Polyphosphates

Phosphates used as chelators include sodium and potassium orthophosphates (Na2HPO4, NaH2PO4, K2HPO4, KH2PO4), sodium pyrophosphates (Na4P2O7, Na2P2H2O7), sodium tripolyphosphate (Na5P3O10) and sodium hexametaphosphates (NaPO3)n

Sodium pyrophosphate and sodium tripolyphosphate are the most effective chelators

Phosphoric acid also functions as a synergist with other antioxidants in vegetable shortening

ADI 0-70 mg/kg bw

No adverse effects in low dosages

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Polyphosphates63

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b. EDTA

Ethylenediamietetraacetic acid (EDTA) and its salt are used as chelating agents

Highly effective in a wide variety of food products

EDYA forms stable water soluble complexes with many di- or polyvalent metal ions

Maximum chelating efficiency occurs at higher pH values where the carbonyl groups are dissociated.

White crystalline powder sparingly soluble in water

ADI 2.5 mg/kg bw

LD50 2000-2200 mg/kg bw

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EDTA65

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c. Tartaric Acid

Occurs naturally in many fruits and is a by product of wine making

Tartaric acid and its salts are used as synergist and acidulants in a number of products such as confectionary, bakery products, and soft drink

Colorless, odorless, crystalline, soluble in water

ADI 0-30 mg/kg bw

LD50 4360 mg/kg bw

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Tartaric acid67

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d. Citric Acid

Citric acid and its salts are widely used as chelators and acidulants

Used as a synergist both with primary antioxidants and oxygen scavengers at levels of 0.1-0.3%

In fats and oils, citric acid chelates metal ions at levels of 0.005-0.2%

White, odorless, highly soluble in water

ADI not limited

Low order of toxicity

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Citric Acid69

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e. Citrate Esters

Esters of citric acid like isopropyl citrate mixture and stearyl citrate

Readily soluble in fats and oils

LD50 of isopropyl citrate is 2800-2250 mg/kg bw

LD50 of stearyl citrate is >5400 mg/kg bw

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f. Phytic Acid

Potential chelating agent

At low pH, it precipitates Fe3+

At intermediate and high pH, it forms insoluble complexes with all polyvalent cations

Phytic acid also prevents browning by inhibiting polyphenol oxidase activity

LD50 450-500 mg/kg bw

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g. Lecithin

Phosphadityl choline functions as potent synergist in fats and oils with a range of primary antioxidants and oxygen scavengers

Highly effective in ternary mixture with vitamin E and vitamin C; or a mixture comprises of ascorbyl palmitate, alpha tocopherol, and lecithin

The mechanism of acton of lecithin is not clear

ADI not limited

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Thiodipropionic Acid (TDPA)

Dilauryl Thiodipropionate (DLTDP)

Distearyl Thiodipropionate (DSTDP)

XIV. SECONDARY ANTIOXIDANTS

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TDPA has the ability to chelate metal ions and also functions to decompose alkyl hydroperoxides into more stable compounds

DLTPD was oxidized to sulfoxide and prevent the oxidation of cholesterol

TDPA has beed approved for food use

ADI 0-3 mg/kg bw

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Thiodipropionic acid75

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a. Nitrates and Nitr i tes

b. Amino Acids

c. Spice Extract

d. Flavonoids

e. Vitamin A

f . Beta Carotene

g. Tea Extract

XV. MISCELLANEOUS ANTIOXIDANTS

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a. Nitrates and Nitrites

Nitrates and nitrites probably function as antioxidants by converting heme proteins to inactive nitric oxide form and by chelating metal ions

Nitrosylmioglobin reacts with peroxy radicals terminating the oxidative chain reaction

Nitrites and nitrates form nitrosamines in food or body

Nitrosamines are powerful carcinogen, mutagen, teratogenic properties

ADI 0-5 mg/kg bw for sodium nitrates and 0-0.2 mg/kg bw for sodium nitrites

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b. Amino Acids

As primary antioxidant and as synergist

At lower concentrations most of AA have antioxidant properties, but at higher concentrations they function as prooxidants

At low pH, most AA are prooxidants, while higher pH favors antioxidant activity

Glycine, tryptophan, methionine, histidine, proline, and lysine are effective in fats and oils

Glycine has been listed as GRAS for addition to fats and oils

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c. Spice Extract

Potential naturally occurring antioxidants

Effective in fats, baked goods, and meat products

Vanillin, eugenol from cloves, cucurmin from tumeric

Limited use due to color, odor, and taste

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d. Flavonoid

Naturally occurring phenolics in common edible plants

Functions as primary and chelator antioxidants

Not being used commercially due to insufficient or adverse toxicological effects

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e. Vitamin A

Very limited used as antioxidant because of its high susceptibility to oxidation on exposure to light and air, conditions under which vitamin A becomes prooxidant

Retinol is effective in fats and oils when kept in the dark

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f. carotene

Mainly used as food colorant

Effective quenchers of singlet oxygen

Has been chemically synthesized

Insoluble in water and slightly soluble in vegetable oils

Very sensitive to oxidative decomposition when exposed to air and light

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Oksigen singlet83

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Fotooksidasi84

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g. Tea Extract

Potential source of natural antioxidants for food products

Extracts of black and green tea are highly effectove in fats and oils

Polyphenols present in tea have antioxidant properties

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Latihan

1. Suatu perusahaan makanan akan mengembangkan sirupjahe. Permasalahan yang timbul pada saat riset adalahselama penyimpanan sirup jahe mengalami perubahanwarna menjadi coklat. Apa penyebabnya? Bagaimanacara mengatasinya? Apakah diperlukan antioksidan?

2. Antioksidan apa yang sesuai untuk produk berikut, jelaskan alasannya:

a. Permen susu

b. Margarin

c. Minyak goreng

d. Roti

e. Keripik kentang

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Thank You

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