ANTIOXIDANT

KULIAH BAHAN TAMBAHAN MAKANANTEKNOLOGI INDUSTRI PANGAN

UNIVERSITAS PADJADJARAN2011

PENGERTIAN

Substansi yang dapat menetralisir radikal bebas dan mencegah kerusakan yang ditimbulkan o/ radikal bebas dengan melengkapi kekurangan elektron yg dimiliki radikal bebas dan menghambat terjadinya reaksi berantai dari pembentukan radikal bebas yg dpt menimbulkan stres oksidatif

Antioxidant O-2, 1O2, .OH, H2O2,

Cu, Fe. R•, RO•, ROO •

R•, RO•, ROO•,

1O2, O-2,

-OH, H2O2,

Cu, Fe

Prooxidant Jail

Are you ready to fight the attack of prooxidants?

Antioxidants in Food

Antioxidants aim to:• prevent food containing fat or oil from going rancid due to oxidation, i.e. developing an unpleasant odour or flavour;

• prevent the browning of cut fruit, vegetables and fruit juices (and so increase shelf life and appearance).

Preventive Antioxidants

Superoxide dismutase Catalase Glutathione peroxidase Singlet oxygen quencher Transition metal chelators (EDTA)

Preventive antioxidants minimize the formation of initiating radicals

Minimization of Lipid Oxidation

If a compound inhibits the formation of free alkyl radicals in the initiation step, or if the chemical compound interrupts the propagation of the free radical chain, the compound can delay the start or slow the chemical reaction rate of lipid oxidation.

The initiation of free radical formation can be delayed by the use of metal chelating agents, singlet oxygen inhibitors, and peroxide stabilizers.

The propagation of free radical chain reaction can be minimized by the donation of hydrogen from the antioxidants and the metal chelating agents.

14 13 12 11 10 9

- H

CH2 CH CH CH2 CH CH CH2 R(CH2)3CH3

Initiation

13 12 11 10 9

+ 3O2

(C H2)4

C H3 C H C H C H C H C H

2RC H

Mechanism of Antioxidant

Metal

Energy

Reactive oxygen species

Lipoxygenase

Substrate effect

Oxygen consumption,

Conjugated diene

Electron spin resonance

mv

K=109/sec

(K= 10o M-1sec-1) + H from RH (triglyceride)

(CH2)4CH3 CH CH CH CH CH2 RCH

O

O

Propagation

13 12 11 10 9

OHC(CH3)

3

OCH3

from

01000mv

0 300-500mv

(K= 107 M-1sec-1)

R.

OC(CH3)

3

OCH3

.

- OH

CH CH CH CH CH CH2 R(CH2)4CH3

O

O

H

(C H2)4

C H3 C H C H C H C H C H2 RC H

O

C H 3 (C H 2)4 C HO

13 12 11 10 9

13 12 11 10 9

Termination

Most reactive oxygen speciesPeroxide value

(C H2

)3

C H3 C H3

0mv

Sensory evaluation

Volatile compounds

Transition Metal

0mv

Kinds of Antioxidants

Natural antioxidants:(a) senyawa antioksidan yang sudah ada dari satu atau dua komponen makanan(b) senyawa antioksidan yang terbentuk dari reaksi-reaksi selama proses pengolahan(c) senyawa antioksidan yang diisolasi dari sumber alami dan ditambahkan ke makanan sebagai bahan tambahan pangan.

Antioksidan Alami

1.Tocopherols (delta>gamma>beta>alpha)

2.Flavonoid 3.Ascorbic Acid 4. Sesamol 4.Gossypol

Radical scavenging antioxidants break free radical chain reaction by donating hydrogen to free radicals

SYNTETIC ANTIOXIDANTS

BHA (Butylated hydroxy anisole)

BHA is a mixture of two isomers. Referred to as a 'hindered phenol' because of the proximity of the tertiary butyl group to the hydroxyl group. This may hinder the effectiveness in vegetable oils, but increase the 'carry through' potency for which BHA is known.

Uses: Lard, shortenings, vegetable oils, cereals, package liners, potato products, dry soups, chewing gum, etc. Usually in combination with other primary antioxidants.

OH

C(CH3)3

OCH3

Butylated Hydroxy Anisole

BHT (Butylated hydroxy toluene)

Butylated hydroxy toluene is also a 'sterically hindered' phenol Susceptible to loss through volatilization in high temperature applications.

Uses: Lard, shortening, vegetable oils, cereals, animal feeds, etc. Usually used in combination with BHA or BHT and citric acid.

Sinergic used with BHA & low price

C(CH3)3(CH3)3C

CH3

OH

Butylated hidroxy toluene

Propyl Gallate

Three hydroxyl groups make it very reactive. Lower solubility. Tend to chelate trace minerals such as iron and form colored complexes. Are heat labile, especially under alkaline conditions.

Uses: Lard, shortening, vegetable oils, cereals, package liners, animal feeds, etc. Used alone and in combination with BHA or PG and citric acid.

OH

OHOH

COOC3H7Propyl Galat

TBHQ (Tertiary-butylatedhydroquinone)

Tertiary-butylatedhydroquinone is an extremely potent antioxidant. Had been used extensively in non food applications prior to gaining approval in food.

Uses: Lard, cottonseed oil, potato chips, corn flakes

kemampuan antioksidan sangat baik pada penggorengan tetapi rendah pada pembakaran.

OH

C(CH3)3

OHTBHQ

Combination Antioxidants Combinations

Antioxidants are usually combined to take advantage of their differing properties.

For example BHA may be combined with PG and citric acid. The citrate chelates metals, the propyl gallate provides a high level of initial protection while the BHA has good carry through properties.

Reasons for Combinations Take advantage of different properties Allow for better control and accuracy May provide synergistic effects Combinations may provide more complete distribution in

some foods More convenient to handle

Synergism in Lipid Oxidation

Synergism occurs when mixtures of antioxidants produce a more pronounced activity than the sum of the activities of the individual antioxidants when used separately.

To have maximum efficiency, primary antioxidants are often used in combination with (1) other phenolic antioxidants, or with (2) various metal chelating agents.

Jenis Antioksidan Berdasarkan Mekanisme Kerja Antioksidan primer Antioksidan sekunder

Antioksidan Primer

Merupakan antioksidan yang berfungsi sebagai pemberi atom hidrogen.

Senyawa ini dapat memberikan atom hidrogen secara cepat ke radikal lipida (R*, ROO*) atau mengubahnya ke bentuk lebih stabil.

Sementara turunan radikal antioksidan (A*) tersebut memiliki keadaan lebih stabil dibanding radikal lipida.

Mekanisme Kerja Antioksidan Primer

(a) pemberian hidrogen (b) pemberian elektron (c) penambahan lipida pada cincin aromatik

antioksidan (d) pembentukan kompleks antara lipida dan

cincin aromatik antioksidan.

Reaksi Penghambatan antioksidan

primer terhadap radikal lipida: Inisiasi : R* + AH RH + A*

Radikal lipida

Propagasi : ROO* + AH ROOH +

A*

Antioksidan Sekunder

Merupakan antioksidan yang berfungsi memperlambat laju autooksidasi dengan berbagai mekanisme diluar mekanisme pemutusan rantai autooksidasi dengan pengubahan radikal lipida ke bentuk lebih stabil.

Mekanisme Kerja Antioksidan Sekunder

Antioksidan sekunder ini bekerja dengan satu atau lebih mekanisme berikut

(a) memberikan suasana asam pada medium (sistem makanan)

(b) meregenerasi antioksidan utama (c) mengkelat atau mendeaktifkan kontaminan

logam prooksidan (d) menangkap oksigen (e) mengikat singlet oksigen dan mengubahnya

ke bentuk triplet oksigen.

Metode Analisis Antioksidan

Metode Kualitatif Uji Warna Spektrofotometri IR DPPH (Diphenyl pycril Hidrazil)

Metode Kuantitatif Metode ORAC (Oxygen Radical Absorbance

Capacity) Iodimetri dan iodometri

Factors Affecting the Efficiency of Antioxidant

1. Activation energy of antioxidants to

donate hydrogen should be low

2. Oxidation potential should be high

3. Reduction potential should be low

4. Stability to pH and processing.

5. Solubility in oil should be .

Antioxidant Safety

Total concentration of authorized antioxidants added singly or in combination, must not exceed 200 parts per million by weight

on the basis of fat content of the food.

Possible Future Antioxidants

1. Polymeric antioxidant.

2. Antioxidant attached to the packaging materials.

3. Development of new, non-absorbable polymeric

antioxidants for use in foods.

Ideal Antioxidants

•No harmful physiological effects

•Not contribute an objectionable flavor, odor, or color to the fat

•Effective in low concentration

•Fat-soluble

•Carry-through effect No destruction during processing

•Readily-available

•Economical

•Non-adsorbable, if possible