ABSTRACT

Microorganisms cause food spoilage in two ways. The first, and the more important one, is through the growth and active metabolism of food components by live cells. The second is produced, even in the absence of live cells, by extracellular and intracellular enzymes that react with food components and change their functional properties, leading to spoilage. The loss of food by microbial spoilage has economic consequences for producers, processors, and consumers. With the increase in world population, loss of food by microbial (and nonmicrobial) spoilage means that less food is available for the hungry mouth. World population in 2011 was about 7 billion, and it is expected to reach 8 billion in 2025 and 9.1 billion in 2050. To fight world hunger, efforts should be directed not only toward increasing food production, but also to minimizing spoilage so that enough food is available for consumption. 1 Many preservation methods have been devised to reduce microbial spoilage and are discussed in Part VI. Under certain methods of preservation, both raw and partially processed (semipreserved, perishable, nonsterile) foods are susceptible to microbial spoilage. This is more evident in foods that are expected to have a long shelf life. To reduce loss of raw and partially processed foods by microbial spoilage, two points are important. One is to predict how long a food, following production, will stay acceptable under the conditions of storage normally used for that food; that is, what will be the expected shelf life under normal conditions of handling and storage. The other is to determine the current status, with respect to spoilage, of a food that has been stored for some time. This information needs to be available well before a food develops obvious detectable spoilage and therefore becomes unacceptable.