Control of the moisture content of food is one of the oldest
preservation methods. Removal of water from the food prevents growth of
most microbes and slows down enzymatic deterioration.
Water removal from food can have several forms. The oldest and most
primitive method for removing water is sun drying, which requires long
hot days with low humidity to dry food evenly and quickly. Over-drying
and uneven drying will result in nutrient destruction, microbial growth,
and other undesirable changes. Drying of food in the home can be done
and a later chapter tells how.
Water activity or availability of water in foods can also be controlled
by adding compounds to the food which tie up the water chemically,
making it unavailable for use in an enzymatic reaction or for use by the
micro-organisms. The two most common home ingredients used in this way
are sugar and salt. In making fruit preserves, the high sugar content
ties up the water and helps prevent growth of many micro-organisms.
Methods used for preserving food in the home are combinations of the
basic techniques discussed here. Make certain the recipe you follow is
from a reliable source. Follow it precisely and be assured of a safe and
wholesome food supply.