Butylated hydroxytoluene

Butylated hydroxytoluene or BHT (3,5-di-tert-butyl-4 hydroxytoluene) is a synthetic antioxidant which prevents oxygen-induced lipid deterioration by acting as a ‘chain breaker’ in a series of free-radical reactions.

It has a molecular structure and performance similar to BHA. Both BHA and BHT are extremely soluble in edible fats and oils and have practically no water solubility. It is susceptible to loss by volatilization and distillation under, certain food processing conditions, such as frying.

This behavior is technologically useful in food processing because the products of rancidity produce an offensive flavor, decrease the nutritional value of food, and may have deleterious health consequences when ingested.

In negative aspect of BHT, is that it may give a yellow coloration due to the formation of stilbenequinone in the presence of iron.

First patented in 1947, BHT was initially used as an industrial antioxidant in the petroleum and adhesive industries and later in the 1950s as a food and cosmetic additive. In foods, BHT may be used to a 0.02% concentration, whereas in cosmetics it is used in a 0.01% to 0.1% concentration.
Butylated hydroxytoluene

The Effectiveness of Antioxidants

The Effectiveness of Antioxidants
Some antioxidants lose their effectiveness when they combine with oxygen; therefore, there is no advantages to using this type of antioxidant unless the food is enclosed in a system from oxygen or air can be excluded. In the use of antioxidants, it should be kept in mind that other precautions are necessary to minimize oxidation since heat, light, and metals are prooxidants, that is, their presence favors oxidative reactions.

Many of the antioxidants used in commerce occur naturally in foods (e.g., vitamin C, citric acid, amines, and certain phenolics compounds). However, the amines and the phenolics compounds can be toxic to human in low concentrations; therefore, they and the synthetic antioxidants require strict regulations of their use in foods.

It should be pointed that the potency of the naturally occurring antioxidants is not as great as that of the commonly used synthetic antioxidants. The antioxidants that are considered to be the most effective and therefore are most widely used are butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propylgallate.

These are usually used in formulations that contain combinations of two or all three of them, and often in combination with even fourth component, very often citric acid. The main purpose in adding citric acid is for its action as a chelator.

Fats and shortening, especially those used in bakery goods and fried foods, are subject to oxidation and the development of rancidity after cooking. To prevent this, chemical antioxidants in concentrations up to 0.02% of the fat components may be added.
The Effectiveness of Antioxidants