f. Additives Used Before Freezing. The most common treatment given to
fruits in preparation for freezing is the addition of sugar or sugar syrup. Sugar protects
the fruit from air and also slows up enzyme activity. The amount of sugar used will
generally vary from 20 to 50 percent. Sulfur dioxide or vitamin C is often added to fruits
prior to freezing to preserve their natural color.
3-24. PRESERVATION OF VEGETABLES
a. Moisture Content and Microbial Count. Vegetables are preserved by
dehydration by reducing the water content to such a point that bacteriological and
chemical changes are prevented. The moisture content of dehydrated vegetables will
vary from 5 to 20 percent. The average moisture content will be about ten percent.
Dehydrated vegetables with low sugar content will have moisture content of five to ten
percent. Those vegetables having high sugar content will have moisture content of 15
to 20 percent when dehydrated. Many dehydrated vegetables will have a total microbial
count in excess of 500,000 organisms per gram. Yeasts are uncommon on dehydrated
vegetables. Molds are commonly found on dehydrated vegetables, but they are not as
common as bacteria. The total microbial count will gradually reduce with age. The
number of microorganisms on dried fruits is much smaller than the number on
b. Preparing Vegetables for Freezing. Frozen vegetables will normally have a
much higher microbial count than frozen fruits. A temperature of 0F (-18C) or less is
desirable for freezing and storing vegetables. All vegetables must be blanched prior to
freezing. Blanching is carried out to inactivate enzymes and is accomplished at a
temperature of 194F to 212F (90 to 100C) for one to five minutes. Steam or hot water
may be used for blanching. A desirable bacterial content in the finished product is less
than 80,000 organisms per gram. Vegetables with such a count are considered to have
been properly processed. Proper processing includes the following steps:
(1) Blanching at a high enough temperature to destroy all surface bacteria
except spore forming bacteria.
Cooling rapidly in potable water following blanching.
Proper handling before and after freezing.
3-25. ACCEPTABLE DISINFECTION PROCEDURES FOR FRUITS AND
Fresh fruits and vegetables grown in areas where human fecal material is used
as a fertilizer and/or where gastrointestinal or parasitic diseases may be expected to be
prevalent are NOT consumed raw except on the approval of the surgeon. Where
vegetables are grown in areas fertilized with human fecal material, no leafy vegetables
are served raw except with the approval of the surgeon, in which case they are cleaned
and disinfected in the same manner as prescribed for hard-skinned fruits and