c. Spoilage of Fruit Juices.
(1) Flat or buttermilk flavor. The lactobacilli are important in the spoilage of
fruit juices. Some strains are quite acid tolerant and can metabolize citric and malic
acid. This reduces the acidity and results in a bland, rather flat flavor and a loss in
astringency. A buttermilk flavor results in the fruit juice.
(2) Slimy consistency. Bacteria of the species Leuconostoc mesenteroides
produces a slimy, unpleasant consistency of fruit juices.
(3) Fermentation. Yeasts contaminate and ferment fruit juice, especially
apple juice. The sugars are fermented to alcohol which is converted to acetic acid,
giving the fruit juice a vinegar flavor.
d. Spoilage of Meat Products. Canned meat products are subject to the same
type of spoilage as other low-acid foods, if heat-resistant spores which survive the
process can germinate and grow. In semipreserved or pasteurized cured products,
such as canned ham, the curing salts and refrigeration are used to prevent spore
germination and growth. If not adequately processed, thermoduric cells, such as
Streptococcus faecium, may survive and cause souring. This organism may cause
rapid discoloration after the product is removed from the can. If the spores of clostridia
are able to germinate, gas may be formed along with extensive putrefaction.
e. Spoilage of Salad Dressing. The spoilage of mayonnaise and salad
dressings is caused by Saccharomyces bailii and Lactobacillus fructivorans. Rather low
numbers of the yeast and bacteria are present in the spoiled product.
f. Spoilage of Tomato Juice. Canned tomato juice is subject to flat sour
spoilage if not properly handled either during preparation or final heat treatment. Flat
sour spoilage is attributed to the presence of and growth of Bacillus coagulans, which
either survives normal heat processes or recontaminates the product. Detection of
spoilage is made by flavor, pH, and odor.
g. Spoilage of Assorted Products. Cereals, honey, molasses, syrup, and
candy ordinarily have water activities too low to support the growth of bacteria.
However, due to storage at high relative humidity or production of water by metabolism,
bacteria can be responsible for the spoilage of these products.
h. Spoilage of Bottled Sauces. The gas-forming Lactobacillus lycopersici
causes fermentation in tomato catsup, other tomato products, Worcestershire sauce,
and similar products.
i. Spoilage of Canned Peaches and Pineapple. Canned pineapple
occasionally exhibits spoilage caused by gas-formers, Leuconostoc mesenteriodes.
This organism may also cause ropiness in canned peaches.