(1) Timing of adding
It can be seen from the mechanism of antioxidants that antioxidants can only hinder lipid oxidation.
Delay the time when the food starts to spoil, but cannot change the consequences of the already spoiled, so antioxidants should be added as soon as possible. It has been reported that adding antioxidants (BHA and BHT) in the boiling oil process is more effective.
Vegetable oil vacuum deodorization is the last step in the oil processing process. Since phenolic antioxidants are volatile under the conditions of oil deodorization, they must be added under cold cycle conditions, or after the deodorized fat is pumped to the storage tank Add antioxidants.
Fried foods can usually absorb a lot of fat. Therefore, fresh fat must be continuously added to the fryer. At the same time, fresh antioxidants are also introduced to replace the loss caused by steam distillation. Often add methyl polysiloxane (Methy1 polysi1oxane) below 10mg/kg in frying oil. Although it is not an antioxidant, it has no direct effect on the stability of the final product, but it can form an insoluble on the surface of the oil. The film prevents the fat from being exposed to the air, thereby protecting the hot fat during the frying process.
(2) Appropriate usage
Unlike preservatives, the amount of antioxidants added is not always positively correlated with the antioxidant effect. When a certain concentration is exceeded, not only does it no longer enhance the antioxidant effect, but has the effect of promoting oxidation. For example, tocopherol can produce very high efficacy at a lower concentration, which is equivalent to its concentration in crude vegetable oil. However, under certain conditions, tocopherol has an oxidative effect, such as -tocopherol. (TH2) When the concentration is higher, free radicals are formed to promote oxidation according to the following reactions:
ROOH TH2 ==== RO· TH· H2O
(3) Synergistic effect of antioxidants
Where two or more antioxidants are used in combination, the antioxidant effect is often greater than the sum of the single use. This phenomenon is called the synergy of antioxidants. It is generally believed that this is because different antioxidants can terminate the chain reaction of oil oxidation at different stages. Another synergistic effect is that the main antioxidant is used in combination with other antioxidants and metal ion chelating agents. For example, ascorbic acid can be used as the main antioxidant regenerating agent (electricity donor), oxygen scavenger, metal chelating agent, and its oxidative browning The product also has antioxidant activity. The above two synergistic effects have been proven in practice and are commonly used in anti-oxidation of oils and fats.
(4) Dissolution and dispersion
The solubility of antioxidants in oil affects the antioxidant effect. For example, water-soluble ascorbic acid can be used in the form of its palmitate to prevent oxidation of oils. Oil-soluble antioxidants often use solvent carriers to incorporate them into fats or fat-containing foods. These solvents are propylene glycol or a mixture of propylene glycol and glycerol monooleate. Antioxidant is added to pure oil. It can be directly added in the form of a concentrated solution under stirring conditions (60 degree ), and must be stirred for a period of time under the condition of eliminating oxygen to ensure that the antioxidant system can be evenly divided.
Spread into the entire grease.
