LESSON 2
INSPECTION OF FOOD CONTAINERS
Section I. INCUBATION AND MEASURING VACUUM
2-1.
GENERAL
The veterinary food inspection specialist must know basic inspection skills for
food containers. These include: (1) checking for a specific vacuum (when requirements
so state), (2) receiving and acting on USDA reports after the adequacy of commercial
sterilization has been determined by testing, (3) checking for a range of possible
container defects of canned food items, glass containers, and retort pouches.
2-2.
INCUBATION
The U.S. Department of Agriculture (USDA) is the agency responsible for
incubating samples of canned meats. It requires that representative sample cans from
each retort be incubated 10 days at 90oF (32oC) to 100oF (38oC) to test the adequacy of
commercial sterilization. The most desirable standard is to maintain a constant
temperature of 98oF for the 10-day period. The inspector responsible for checking the
incubation process may extend the 10-day period when he believes sanitary conditions
in the processing or the condition of the machinery have deteriorated to such an extent
that the prolonged period is necessary. The purposes of incubation are: to check the
adequacy of processing, to assure acceptable or satisfactory commercial sterilization,
and to assure the product will keep without refrigeration under normal conditions of
storage and shelfing. Food items that are processed without steam pressure cooking
are deemed unacceptable for storage under normal conditions so they must be labeled
"PERISHABLE-KEEP REFRIGERATED." Lots of a food item, samples of which are
under incubation, may be shipped to the purchaser subject to being withdrawn from the
market if incubation shows that the product is unacceptable for consumption.
2-3.
VACUUM REQUIREMENTS
a. Vacuum. The dictionary definition of a vacuum is a space with nothing at all
in it, completely empty space, devoid of all matter, or space containing air or gas at a
pressure below that of the atmosphere, or the degree to which pressure has been
brought below atmospheric pressure. In the canning industry, the meaning of vacuum
is a little different; it is the extent to which air has been eliminated from the can, resulting
in a pressure reduction below atmospheric pressure.
b. Measurement. Measurement, in the canning industry, is measuring the
difference between atmospheric pressure and the existing lower pressure in the closed
MD0708
2-3