Flat sour is probably due to imperfect sterilization.
(c) PUTREFACTION.—When putrefaction takes place, food decays and disintegrates, or decay takes place with the production of a gas of a disagreeable odor. This type of spoilage is readily detected. Food thus affected is unfit for use.
Putrefaction is usually caused by imperfect sealing. It may result, however, from imperfect sterilization.
(d) BOTULISM.—A bacillus termed botulinus sometimes grows on canned foods, especially those rich in protein or lacking in acid. This organism produces a violent poison in the food. But fortunately, the poison may be destroyed by boiling the food for ten minutes. Hence, it is advisable to boil canned food at least 30 minutes before using. This should be done even though the food is to be served cold. It may easily be cooled after boiling. When there is the least suspicion that food is spoiled, it should be discarded.
QUESTIONS
Explain why boiled milk keeps sweet for a longer time than uncooked milk.
Why do foods need to be sealed to preserve them?
Why does cooked meat "keep" longer than uncooked meat?
LESSON CLXVII
PROCESSING WITH LITTLE OR NO SUGAR—CANNED FRUIT
JARS FOR CANNED FRUIT.—There are many types of fruit jars. Glass jars rather than metal cans should be used for home canning. Jars should be constructed so that there is no contact of the fruit with metal, hence a jar having a glass cover is desirable. A large opening, simple construction, ease in cleaning, and perfect sealing are characteristics of good fruit jars.