Sanitation and microbiology as related to vegetable dehydration by Olson R. L & United States. Bureau of Agricultural & Industrial Chemistry

Author:Olson, R. L & United States. Bureau of Agricultural & Industrial Chemistry
Language: eng
Format: epub
Tags: Vegetables Drying
Publisher: Albany, Calif. : U.S. Dept. of Agriculture, Bureau of Agricultural and Industrial Chemistry
Published: 1952-03-25T05:00:00+00:00

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To meet the second and third requirements, the selection of sound raw material and maintenance of reasonably sanitary conditions at all Ftages of the process offer the most satisfactory means of control. Where blanching processes are used, the hot-water or steaming operation achieves a virtual sterilization of the product and bacteriological control centers on avoidance of undue recontamination thereafter, Conveyors, cooling waters (especially -'here recirculation occurs), workers' hands, trays,, tray-loading equipment, and air-borne microorganisms may all contribute to such recontamination. With uneven tray loading and non-uniform heat distribution in dehydrators , low-temperature pockets may occur- that will allow the build-up of very high microbial content and, in some cases, result in product spoilage during dehydration, even though the general temperature conditions in the dehydratcr are satisfactory.

If the product is blanched on the trays that are used in the drier, much of the opportunity for recontamination may be avoided. By this means it is possible to keep bacterial fl^ra at a very low level.

Other means of reducing the recontamination involve continuous sanitation of conveyors and use of chlorine or other sanitizing agents in cooling, conveying, and washing waters and during clean-up operations. The establishment of sanitary proced\tres, including the maintenance of a duit-free atmosphere, will do much to reduce recontamination of the product.

An important aspect of control of microbial organisms in dehydrated foods when served is the method of rehydration. While cooking will generally reduce bacterial content, long periods for rehydration at temperatures allowing bacterial growth can be responsible for spoilage or, possibly, development of dangerous levels of toxigenic or pathogenic organisms that may be present. The period of rehydration, in general, should not exceed four hours. A summary of the microbiological aspects of vegetable dehydration follows:

1, Raw vegetables will enter the plant with a heavy bacterial load.

2. Preparation and blanching remove or kill most of the microbes. Bacterial spores will survive blanching and dehydration.

3* Recontamination after blanching (including contamination of the dehydrated product) is the most general source of bacteria on dehydrated vegetables.

U. Improper tray loading or cool pockets in a dehydrator will allow bacterial growth during dehydration,

5. Viable bacteria tend to die out during storage out dehydrated vegetables are never sterile.

6. Rehydrated products are very perishable and should be handled accordingly.

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