Of the chemical compounds that have been investigated thus far, three have been found to be outstandingly effective antioxidants for feeds and feed ingredients and can be used both efficiently and economically. They are:
(a) Ethoxyquin (generic term: 1,2-dihydro-6-ethoxy-2,2,4- trimethylquinoline)
(b) BHA (butylated hydroxyanisole);
(c) BHT (butylated hydroxytoluene)
Ethoxyquin, however, has been demonstrated to be the most efficaceous, followed closely by BHT and BHA.
With the advent of rations containing a high level of animal and vegetable fats, the requirement for antioxidant protection has become very apparent. The majority of studies over the last few years has focused on ethoxyquin as a preservative or antioxidant. Other chemical preservatives are: ascorbic acid, propionic acid, benzoic acid, citric acid and their various salts. There are technological problems (i.e., moisture level, etc.) associated with the use of these preservatives. Economics, however, remain the most important consideration which limit their use in fish foods.
A list of chemical preservatives appears in Table 1.
Table 1 Commonly Used Chemical Preservatives Generally Recognized as Safe