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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
2
II. ANTIOXIDANTS
Retard the lipid oxidation reaction
Are used to stabilize fats and oils, high fat foods, cereals, product containing small amount of lipids
3
III. DEFINITION
According to Food and Drug Administration
Substances used to preserve foods by retarding deterioration, rancidity, or discoloration due to oxidation
4
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
5
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
6
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
8
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
9
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
10
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
12
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
13
A. Phenols
B. Hindered Phenols
C. Miscel laneous Primary Antioxidants
XII. PRIMARY ANTIOXIDANTS14
15
A. PHENOL
a. Gallates (PG, OG, DG)
b. Hydroquinone (HQ)
c. Trihydroxy butyrophenone (THBP)
d. Nordihydroguairetic acid (NDGA)
16
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
17
Propyl Gallate18
Octyl Gallate19
Dodecyl Gallate20
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
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
24
Trihydroxy Butyrophenone25
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
26
Nordihydroguairetic Acid27
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
29
BHA30
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
31
BHT32
BHT33
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
TBHQ36
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
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
39
Guaiac gum40
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
41
Ionox 22042
Ionox 10043
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
45
Ethoxyquin46
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
47
Anoxomer48
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
49
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
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
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
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
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
56
Ascorbyl palmitate57
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
58
Erythorbic acid59
Sodium Erythorbate60
a. Polyphoshpates
b. EDTA
c. Citr ic Acid
d. Citrate Esters
e. Phytic Acid
f . Lecithin
B. CHELATING AGENTS61
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
62
Polyphosphates63
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
64
EDTA65
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
66
Tartaric acid67
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
68
Citric Acid69
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
70
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
71
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
72
Thiodipropionic Acid (TDPA)
Dilauryl Thiodipropionate (DLTDP)
Distearyl Thiodipropionate (DSTDP)
XIV. SECONDARY ANTIOXIDANTS
73
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
74
Thiodipropionic acid75
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
76
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
77
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
78
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
79
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
80
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
81
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
82
Oksigen singlet83
Fotooksidasi84
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
85
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
86
Thank You
87