Bài giảng Phụ gia thực phẩm - Chương 5: Chất chống oxy hóa

Bài giảng Phụ gia thực phẩm - Chương 5: Chất chống oxy hóa có nội dung trình bày về các chất chống nâu hóa, kiểm soát nâu hóa, hóa học của phản ứng hóa nâu trong thực phẩm, quá trình oxy hóa (oxidation),... Mời các bạn cùng tham khảo chi tiết nội dung bài giảng!

PART 2

FOOD ADDITIVES CONTRIBUTING TO IMPROVE THE SHELF-LIFE

Chương 5: ANTIOXIDANTS

Các phản ứng biến đổi màu (nâu hóa) được chia thành 2 loại:

1 Nâu hóa do enzyme

2 Nâu hóa không do enzyme.

Ví dụ:

- Nâu hóa trong quá trình cắt rau quả tươi và tiếp xúc không khí?

- Nâu hóa trong quá trình thanh trùng nước quả?

Nâu hóa do enzyme là kết quả của:

- Oxy hóa các hợp chất polyphenols chuyển thành quinones,

- Được xúc tác bởi các enzyme polyphenol oxidase:

Kiểm soát nâu hóa do enzyme:

1 Sử dụng phương pháp chần,

2 Acid hóa; ứng dụng sulfites

3 or sử dụng các chất thay thế sulfites như:

– ascorbic acid

– cysteine.

Các chất thay thế này hiệu quả kém hơn so với sulfites

Chemistry of browning reactions in foods

• The optimum pH for PPO activity is between 5 and 7

• PPO is relatively heat labile

• and PPO-catalyzed reactions can be inhibited by:

acids

phenolic acids,

sulfites

ascorbic acid

Sulfites

• Sulfite may be applied as:

 E220 Sulphur dioxide

 E221 Sodium sulphite

 E222 Sodium bisulphite,

 E223 Sodium metabisulphite

 E224 Potassium metabisulphite

 E225 Potassium sulphite

 E226 Calcium sulphite

 E227 Calcium hydrogen sulphite,

 E228 Potassium bisulphite

• Sulfite có nhiều dạng tồn tại ở dạng nào tùy thuộc vào bản

chất của thực phẩm

• Do đó nhiều chất tương đồng của sulfite được phát triển để giải quyết vấn đề công nghệ.

E220 (sulphur dioxide) được sử dụng xử lý xông quả chống

hóa nâu Ngoài ra nó cũng có thể sử dụng điều chỉnh độ acid và

chất bảo quản vi sinh

E223 và E224 đặc biệt rất bền khi lưu trữ do đó sử dụng trong các

kho bảo quản là phù hợp.

E226 rất tan ít trong nước nên sử dụng được khi yếu tố hòa tan

không phải ưu tiên hàng đầu

Quá trình oxy hóa (oxidation)

• Oxidation là một phản ứng hóa học chuyển các electron hoặc

hydrogen từ một cơ chất sang chất oxy hóa.

• Phản ứng oxy hóa tạo ra các gốc tự do (free radicals) Sau đó,

các gốc tự do này sẽ tạo ra phản ứng oxy hóa dây chuyền.

Oxidation

ôi hóa (rancidity),

mất mùi vị,

mất màu sắc

mất giá trị dinh dưỡng.

Oxy hóa làm biến đổi thực phẩm:

Oxidation

Mức độ oxy hóa phụ thuộc vào:

1 Tồn tại các chất oxy hóa tự nhiên trong thực phẩm,

2 Có mặt của oxy,

3 độ nhạy của cơ chất đối với phản ứng oxy hóa,

4 nhiệt độ và ánh sáng,

Butylated Hydroxyanisole Butylated Hydroxytoluene

ANTIOXIDANTS

• Often a combination of two or more antioxidants is more

effective than any one used simply because of their synergistic

effects.

• The presence of other agents, such as citric acid , may also have

a synergistic effect, by reducing the availability of metallic ions

that may catalyse oxidation reactions.

.

ANTIOXIDANTS

• The use of the powerful synthetic antioxidants BHA, BHT and the gallic

acid is very restricted

• Tocopherols, which can be either natural or synthetic, are less restricted

but are less effective in the protection of processed foods.

• Antioxidants cannot restore oxidized food ; they can only retard the

oxidation process.

• The most effective use of antioxidants is therefore in the fats and oils

used in the manufacturing process.

• Regulated differently country by country

• Many antioxidant but few approved by:

Joint FAO/WHO Expert Committee on Food Additives (JECFA) European Community’s Scientific Committee for Food (SCF)

citric acid not limited

lecithin not limited

ascorbic acid not limited

sulphites (as sulphur dioxide) 0–0.7

ascorbyl palmitate or ascorbyl 0–1.25

stearate (or the sum of both)

OH OH

DESCRIPTION: White to slightly yellow, odourless crystalline

powder; melting point about 190 o C with decomposition

SOLUBILITY: Freely soluble in water; sparingly soluble in ethanol; insoluble in ether

LOSS ON DRYING

pH : 2.4 - 2.8

MAX LEVEL: GMP (In accordance with good manufacturing practices; or sufficient for purpose;

or quantity not greater than required)

ADI: for ascorbic acid and its Ca, K and Na salts, of 0-15 mg/kg

OH OH

Functional use: Antioxidant

Solubility: Very slightly soluble in water; freely soluble in

ethanol

Melting range: 107 o - 117o

Max level: 5.000mg/Kg

ADI: 0 – 1,25 mg/Kg

OH OH

Description : White or yellowish-white solid, with a citrus-like odour

Functional use : Antioxidant

Solubility : Very slightly soluble in water; soluble in ethanol

Melting point : 116o

Max level : 5.000mg/Kg

ADI : 0 – 1,25mg/Kg

E310 Propyl gallate, E311 Octyl gallate,

E312 Dodecyl gallate

They are fat-soluble and are added to fats and oils to delay or prevent rancidity

E310 Propyl gallate, E311 Octyl gallate,

E312 Dodecyl gallate

Benefits

• Propyl gallate is synergistic with other antioxidants, such as BHA and BHT.

• It is particularly effective with polyunsaturated fats.

• The antioxidant activity is maintained when the fat is blended with other

ingredients in a final foodstuff.

• The longer chain length of the octyl and dodecyl gallates gives advantages over propyl gallate in terms of:

 greater solubility in fats

 and greater stability.

E310 Propyl gallate, E311 Octyl gallate,

E312 Dodecyl gallate

Limitations

The gallates are fat-soluble, but need to be dissolved in a small quantity of hot

fat first before being diluted with the rest of the fat

Chemical names : 3-Tertiary-butyl-4-hydroxyanisole, a mixture of 3- and butyl-4-hydroxyanisole

2-tertiary-DESCRIPTION : White or slightly yellow crystals or waxy solid, with a faint characteristic

odour

SOLUBILITY : Insoluble in water; freely soluble in ethanol and propane-1,2-diol

MAX LEVEL : 200mg/Kg

ADI : 0 – 0,5 mg/Kg

BUTYLATED HYDROXYANISOLE (BHA)

ISN 320

Function in Food

• Butylated hydroxyanisole is an antioxidant and is added to delay or

prevent rancidity in fats and oils in foodstuffs.

• It is insoluble in water and is best suitable to foods with a high fat

content.

• BHA is often used in combination with other antioxidants such as BHT

to give a synergistic effect.

BUTYLATED HYDROXYANISOLE (BHA)

ISN 320

Benefits

BHA is stable to heat and mildly alkaline conditions,

giving it a property that makes BHA particularly

suitable in baked and fried foods

Limitations

BHA is a very effective antioxidant for animal fats, but

its effect is less marked in vegetable oils that are

being stored at ambient temperatures

OH (H 3 C) 3 C C(CH 3 ) 3

O–CH 3

BUTYLATED HYDROXYTOLUENE (BHT)

ISN 321

Chemical names: 2,6-Ditertiary-butyl-p-cresol, 4-methyl-2,6-ditertiary-butyl-phenol

DESCRIPTION: White, crystalline or flaked solid, odourless or having a characteristic faint aromatic

BUTYLATED HYDROXYTOLUENE (BHT)

ISN 321

Function in Food

• Butylated hydroxytoluene is an antioxidant and is added to delay

or prevent rancidity in fats and oils in foodstuffs.

• It is insoluble in water and is best suitable to foods with a high fat content.

• BHT is often used in combination with other antioxidants, such as BHA, to give a synergistic effect.

BUTYLATED HYDROXYTOLUENE (BHT)

ISN 321

Limitations

BHT is more steam-volatile than BHA, and this makes it unsuitable

for use on its own in frying oils, particularly where high-moisture

foods are being fried.

Chelating agent (sequestrant)

METAL IONS

STABLILSED COMPLEX

EDTA (Ethylene Diamine Tetra Acetate)

Calcium Disodium Ethylene Diamine Tetra Acetate

Disodium Ethylene Diamine Tetra Acetate

Polyphosphates

Ortho- , Pyro-phosphoric acid

Isopropyl citrate

CALCIUM DISODIUM ETHYLENE DIAMINE TETRA ACETATE

SYNONYMS : Calcium disodium EDTA

Chemical names: N,N'-1,2-Ethanediylbis[N-(carboxymethyl)-glycinate](4-)-N,N',O,O',ON,ON]calciate(2-) disodium; Calcium disodium ethylenediaminetetraacetate; Calcium disodium (ethylene-dinitrilo)-

tetraacetate

DESCRIPTION: White, odourless crystalline granules or a white to nearly white powder; slightly

hygroscopic

FUNCTIONAL USES : Sequestrant, preservative

SOLUBILITY: Freely soluble in water, practically insoluble in ethanol

pH : 6.5 - 7.5

MAX LEVEL : beverages : 25 – 35mg/Kg, fish : 50, fruits vegetables products 100 – 200, dried vegetables

600 – 800

ADI : 0-2.5 mg/kg

DISODIUM ETHYLENE DIAMINE TETRA ACETATE

SYNONYMS : Disodium EDTA, disodium edetate

Chemical names : Disodium salt of N,N'-1,2-Ethanediylbis[N-(carboxymethyl)glycine]; disodium dihydrogen ethylenediaminetetraacetate; disodium dihydrogen (ethylene-dinitrilo)-tetraacetate

DESCRIPTION: White, odourless crystalline granules or a white to nearly white powder FUNCTIONAL USES : Sequestrant, antioxidant synergist, preservative

SOLUBILITY : Freely soluble in water, practically insoluble in ethanol

pH : 4.3 – 4.7

MAX LEVEL : beverages : 25 – 35mg/Kg, fish : 50, fruits vegetables products 100 – 200,

dried vegetables 600 – 800

ADI : 0-2.5 mg/kg

O –

O –

O P O

O –

O –

O P O

P

O

O NaO

P

O ONa NaO

SYNONYMS : Pentasodium tripolyphosphate, Sodium triphosphate, Sodium tripolyphosphate,

Triphosphate

Chemical names : Pentasodium triphosphate, pentasodium tripolyphosphate

DESCRIPTION : White, slightly hygroscopic granules or powder

FUNCTIONAL USES: Sequestrant, texturizer

SOLUBILITY : Freely soluble in water; insoluble in ethanol

pH : 9.1 - 10.1

MAX LEVEL : 0.6 – 1.0 %

No ADI was established, MTDI : 70 mg/kg

ISOPROPYL CITRATE

INS 384

Chemical names : Citric acid mixed ester of 2-propanol.

FUNCTIONAL USES : Antioxidant, sequestrant

SOLUBILITY : Soluble in water and ethanol

Antioxidative factor (AF) = IA/I0

AF values of some antioxidants (0.02%) in

Octyl gallate Ascorbyl palmitate BHA+BHT

(0.01%+0.01%)

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