c. Control. Freezer burn may be prevented by a skintight covering or an ice
glaze for the food product. The skintight covering may be obtained by the use of water-
impermeable films, dip coatings, or spray coatings.
d. Summary. The deteriorative process, freezer burn, may be summarized by
+ Poor Packaging
Loss of Moisture
+ Low Relative Humidity
Rancidity is a term generally used to denote unpleasant odors and flavors in
foods resulting from deterioration in the fat or oil portion of a food. Three different
mechanisms of rancidity may occur. These are oxidative, hydrolytic, and ketonic.
a. Oxidative Rancidity. Oxidative rancidity arises from the decomposition of
peroxides. Peroxides are the result of the oxidation of unsaturated fats. The products
resulting from the decomposition of peroxides include aldehydes, ketones, and
hydrocarbons. These help to produce the flavors and odors associated with oxidative
(1) Abnormal characteristics. The abnormal characteristics of a product that
has undergone oxidative rancidity are a paintlike or acrid (burning) odor and an
abnormal (rancid) taste. The color of a food item is not normally changed due to this
deteriorative process. An exception to this occurs in waterfoods; a yellowish-brown
discoloration results from the oxidative rancidity process. The texture of a food product
is not affected by the deteriorative condition.
(2) Unsaturated fatty acids . All foods containing unsaturated fatty
acids (UFA) are susceptible to oxidative rancidity.
(a) The rates of formation and intensities of unpleasantness produced
depend upon three factors. These are the composition of the lipid components, their
location in the food, and the conditions of storage. In general, high concentrations of
UFA, especially acids with three or more double bonds, and exposure to air at elevated
temperatures result in rapid development of intense rancidity.