Section IV. DETERIORATIVE CONDITIONS
Food is a very complex item composed of many substances, some of which are
carbohydrates, proteins, fats, water, minerals, vitamins, emulsifiers, stabilizers,
antioxidants, and many others. It is the combination of these components which makes
one food different from another. Also, each of these components is susceptible to a
different form of deterioration, and the changes are subtle and complex. Realizing
these facts, there are several deteriorative conditions that are commonly found by the
veterinary food inspection specialist during inspection of subsistence items.
1-13. FREEZER BURN
Freezer burn is a deteriorative condition commonly found in frozen foods,
especially poultry, waterfoods, and red meats. This condition is a physical change in
the food item that results in no loss of wholesomeness. However, a reduction in quality
of the product and a reduced serviceability does occur.
a. Abnormal Characteristics. The abnormal characteristics that are exhibited
by a freezer-burned product include an abnormal color, usually white or pale amber.
The surface of the product will be dry and shriveled, and usually there is a buildup of
frost on the surface of the product. This texture is similar to that of a dry sponge. A dry,
tasteless, stale product is the result of the deteriorative process.
b. Cause of Freezer Burn. Freezer burn is caused by the evaporation
(sublimation) of moisture from the surface of the food item which results in the product
having a bleached, unattractive appearance and adverse effects on the palatability.
(1) Cause of dehydration. Water vapor always seeks to go from an area of
high concentration to an area of low concentration. In a freezer, the relative humidity is
relatively low because the cold dense air is not capable of holding much moisture.
However, the moisture content of the food may be from 65 to 90 percent, depending
upon the type of food. This uneven concentration of moisture makes frozen foods very
susceptible to moisture loss. Therefore, products which are improperly wrapped and
packaged will be susceptible to dehydration. Freezer burn will result.
(2) Cause of color change. While the buildup of frost on the outside of the
product is caused by the excessive loss of moisture, the color change is caused by
small holes or voids formed in the item. These holes or voids cause the light to be
reflected differently. Therefore, the color changes. The small holes also cause the
product to be more susceptible to the oxidative process; there is an increased area of
exposure to oxygen.