(b) In poultry and fish, rancidity in the skin exceeds that in the flesh. In
red meats (frozen or dehydrated), rancidity is more intense in the lipids of the cells than
in the fats of the adipose or connective tissue. Frozen stored fatty foods rarely exhibit
rancidity upon thawing, but usually develop rancid odors and flavors upon cooking.
(c) At low temperatures, peroxide decomposition is extremely slow,
whereas at high temperatures, it is rapid.
(3) Control techniques. Oxidative rancidity can be retarded by packaging in
the absence of oxygen and by the addition of antioxidants, such as butylated
hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate, tocopherols
(naturally occurring but also added as vitamin E), and others.
(a) Antioxidants are usually more efficient when added to a fatty
ingredient than when added to an intact food.
(b) Incorporation of antioxidants in packaging material in contact with
fried snack foods and ready-to-eat cereals has been helpful in retarding oxidative
rancidity in these products.
(c) Other factors that slow the rate of this chemical reaction are the use
of shorter storage times and the use of low-temperature (freezing) storage.
(4)
Summary. Oxidative rancidity may be summarized by the following.
diagram:
Food (High Amount of UFA)
+ OXYGEN
Peroxides
Organic
Oxidative
Acids
Rancidity
+ High Temperature
+ Time
MD0723
1-16
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