j. Spoilage of Packaged Milk. Occasionally, heat-resisting, anaerobic bacteria
cause trouble in milk packs. The anaerobes produce off-flavors, thinning, curdling, and so forth,
in canned milk.
k. Summary. Figure 6-1 is a summary of microbial conditions found in
Butyric acid, Soft rot
Souring, C02 Acetification (production of acetic acid
or vinegar} Moldy surface, Cloudy, Buttermilk flavor
Jelly, jam preserves
Canned corn, green beans, peas
Flat sour, Sulfide stinker, Putrid swell, Hard swell
Soft, Black, Soft, mushy, slimy, Reduced acidity
Ropy, slime, Black mold, Blue mold, Pink mold,
Moldy, Discoloration, Pink
Gas, souring, putrefaction, discoloration
Figure 6-1. Microbial conditions of semiperishable subsistence.
a. General. Examine the product and note any color, texture, flavor, and/or
odor abnormalities. Check for the presence of oxidative rancidity.
b. Characteristics. Oxidative rancidity is caused by oxidation of unsaturated
fats. Products with a high degree of unsaturated fats are most susceptible to oxidative
rancidity. In freeze-dehydrated items, the rancidity will be in the lean rather than the fat
component of the food item.