42. As has been pointed out, it is not the mere presence of
micro-organisms that causes the spoiling of food, but their constant
growth. Therefore, to keep milk from souring, meat from spoiling, bread
from molding, canned fruit from fermenting, and so on, it is necessary
to know what will prevent the growth of these minute organisms.
Different foods require different treatment. Some foods must be kept
very cold, some must be heated or cooked, others must be dried, and to
others must be added preservatives. An unwarrantable prejudice has been
raised in the minds of many persons against the use of preservatives,
but this is due to the fact that the term is not properly understood. In
this use, it means anything that helps to preserve or keep safe the food
to which it is added. Sugar, salt, spices, and vinegar are all
preservatives, and are added to food as much for the purpose of
preserving it as for seasoning it.