14.2 PRE-STORAGE TREATMENT
All foods must be clean on entry. Vegetables and fruits should be dirt-free and
some, such as fi sh, leaf vegetables and some fruits, may be washed and left
wet. Fish will tend to dry out and lose its fresh appearance, so it is packed
wet or given a sprinkling of ice chips to keep the surface moist. For meat and
poultry the degree of surface microbial contamination is critical.
The shelf life of meat is dependent on the initial numbers of spoilage bacteria
on carcasses. With higher numbers, fewer doublings are required to reach
a spoilage level. Contamination of carcasses may occur at virtually every stage
of slaughtering and processing, particularly during fl aying and evisceration
of red-meat animals and scalding, and mainly affects the surface of the carcass.
Sources of contamination have been reviewed by James et al. (1999). The
adoption of good production practices throughout the slaughtering system and
hygienic handling practices should ensure that bacteria counts on the fi nished
carcass are at an acceptable level. Decontamination methods are also sometimes
applied (James and James, 1997).
Potatoes will start to sprout after a long period in storage. This can be
checked by spraying the freshly lifted tubers with a chemical sprout depressant.
Certain fruits, notably grapes and dates, may have some surface contamination
or infestation when fi rst picked, and they are fumigated with sulphur dioxide or
some other gas. Chlorine washing is also used. They must, of course, then be
thoroughly ventilated before going into storage.
The techniques of this processing will be known to the user or can be found
in sources from the particular branch of the food industry.
Handling conditions must be hygienic. Some types of food, such as milk,
can be kept sealed within the processing system. If the food will be exposed to
the air during handling, the conditions of the surrounding air – in terms of temperature,
humidity and cleanliness – must be the best that can be maintained.
This is especially the case with fresh meats.