Index >> Microbiology of Food >> Preservation of Cereals

Preservation of Cereals - Cereals and cereal products which include grains, flours, bread and other bakery products contain organisms from the soil, insects and other sources. Bacteria found on freshly harvested grains include species of Pseudomonas,Micrococcus, Lactobacillus, Bacillus etc., and the total number of bacteria per gram of grain could vary from a few to several millions. Most of these are, however, removed with the outer portions of the grain during milling.

Bacteria in wheat flour include mostly species of Bacillus, coliforms, Micrococcus, Sarcina, Serratia etc., while mold spores of Aspergillus and Penicillium are also very common.

Bakery products can be stored in a refrigerator or in a frozen condition. Preservatives such as sodium and calcium propionate sodium diacetate and sorbic acid are used in bakery products. Although the microbial load of cereal grain meals and flours may not constitute a spoilage problem by itself, the number and types of microorganisms in such products is of concern since these foods are used in formulation of other foods.

Moist flour will allow mold growth on the surface while a wet mash will undergo acid fermenta­tion by the coliform and lactic bacteria normally present in these materials. As soon as the acidity increases, yeast growth will be favoured. Molds involved in spoilage of baked products include Rhizopus nigricans, Penicillium expansum, Aspergillus niger, Neuro­-para crassa etc., which are generally picked during post baking and storage.