Page 406 - Biosystems Engineering

Extraction, Refining, and Stabilization of Edible Oils 383

The wide array of solid antioxidants and liquid antioxidant blends
available in the market necessitates consideration of the following
factors before using a particular antioxidant in food:

1. The type of food to be stabilized.
2. The need to “carry through” from the oil to the cooked food
product.
3. The ease of antioxidant solubility and disposition into the fat
phase of the product.
4. The presence of metal ions and the possibility of discoloration.
5. The relative severity of processing (e.g., baking versus frying)
and the legality of using a specific antioxidant for a specific
antioxidant application.

13.5.3 Different Types of Antioxidants
There are two types of antioxidants: primary and synergetic.

Primary Antioxidants Different synthetic antioxidants, such as tertiary
butyl hydroquinone, butylated hydroxytoluene, hydroxyanisole, and
tocopherols, for example, have been used in foods to prevent deterio-
ration during storage, transportation, and discoloration from oxida-
tion The primary antioxidants act as follows:
.
1. They can terminate the free-radical chain by donating hydro-
gen to free radicals and converting them to more stable
products.
2. They can form lipid–antioxidant complexes by reacting with
lipid radicals.
3. They may either delay or inhibit the initiation step by react-
ing with a lipid free radical or inhibit the propagation step by
reacting with peroxy or alkoxy radicals.

Synergetic Antioxidants These antioxidants decompose the hydrogen
peroxide formed during the reaction of primary antioxidant with free
radicals and are used synergically with primary antioxidants. Exam-
ples of synergistic antioxidants include phosphates, sulphites, and
thioesters.
Both natural and synthetic antioxidants are used in the food
industry. Recently, there has been an increased demand for natural
antioxidants. When compared to synthetic antioxidants, natural anti-
oxidants have the following advantages:
1. They are readily acceptable by consumers.
2. They are considered to be safe.