a. Four Types of Dehydrated Meat Products. There are four types of meat
products dehydrated in this country at the present time. These four types are cooked
fresh meat, raw fresh meat, cooked cured meat, and raw cured meat.
b. Standard for Dehydrated Fresh Meat. Cooked fresh meat is dehydrated in
the largest volume in this country. It is dehydrated to moisture content of about ten
percent and is then canned. This product has a pH range of 5.8 to 6.2. Salmonella,
Staphylococcus, and Clostridium botulinum organisms will not grow in this product until
it is rehydrated.
(1) Moisture content and toxin production. Moisture content is very
important in the production of toxin by Clostridium botulinum organisms. Toxin will be
produced in 48 hours in meat containing 60 percent moisture and incubated at 98F
(37C). Meat incubated at 98F (37C) containing 40 percent moisture will have toxin
produced in it in 7 days. There will be no toxin produced in meat containing 30 percent
moisture. The above information, relative to toxin production by Clostridium botulinum
organisms, is based upon samples of meat in which Clostridium botulinum organisms
were intentionally introduced in a laboratory experiment.
(2) Mold growth. Mold will grow on dehydrated meat when it is exposed to
the atmosphere and is stored at a relative humidity above 75 percent in a temperature
range of 50 to 99F (10 to 37C). Mold growth is not a problem in canned dehydrated
3-18. PRESERVATION BY CHILLING
Preservation of meat by chill storage is the most extensively used means of
preservation in this country. Chilling prevents the growth of all bacteria except those in
the psychrophilic group. The amount of moisture on the surface of the meat and the
relative humidity in the cooler are of vital importance to the keeping qualities of the
meat. Fresh meat products are stored best at a relative humidity of 85 to 90 percent.
Such a humidity range will strike an effective balance between excessive shrinkage and
discoloration and microbial growth and slime. While chill storage will retard the growth
of all but the psychrophilic group of bacteria, it is not nearly as effective in retarding the
growth of yeasts and molds. Mold organisms, particularly, grow well in the chill
temperature range and create a real problem in the chill storage of fresh meats. Three
factors must be considered in chill storage of subsistence. They are temperature,
relative humidity, and air movement.
a. Temperature. The chill storage temperature range is from 30 to 50F
(-1 to 10C). Temperature requirements for several items of subsistence are: