Food Microbiology

During handling, harvesting and processing operations food may become contaminated with a wide range of microorganisms. Subsequently, during storage and distribution only a small fraction of these will develop and cause serious deterioration. Which microbes will develop or what biochemical reactions occur is dependent upon food derived or environmental factors. Spoilage of food may be caused by a wide range of reactions including some that are mainly physical or chemical, others due to action of enzymes or microbes. The primary factors associated with food spoilage are associated with intrinsic properties of food which include endogenous enzymes, substrates, sensitivity for light, oxygen and cross contamination during slaughter,harvesting and processing in combination with temperature abuse. For fresh foods the primary quality changes may be categorized as (i) bacterial growth and metabolism resulting in possible pH-changes and formation of toxic compounds, gas, slime-formation and off-odors, (ii) oxidation of lipids and pigments in fat-containing foods resulting in undesirable flavors, formation of compounds with adverse biological effects or discoloration. Although interrelated with the microbiological spoilage, the last category is purely chemical in nature and will, all other things being equal increase in importance with decreasing temperature. Little is known about the relationship between microbial activity and biochemical spoilage parameter under different packaging and storage conditions. Although there is much progress in the characterization of the total micro flora and metabolites developing during spoilage, not much is known about the identification of specific microbes in relation to food composition.