36163 tekst
6 (2)

UNIT 15

Ifyou don’t like the heat, get out of the kitchen.

INDUSTRIAL PROCESSING

Processing in a factory is mainly intended to preserze food so that the choice is greater and independent ofgeographical area or theseason of theyear; italso reduces the time spent on preparing food m the home. Tne main commercial processes which cause some loss of nutrients are blanching, heatprocessing, and drying or dehydradon. The freezing process itself has little effect on nutritional value, and sińce the delay after harvesting is minimal the nutrients in fresh foods are generally well retained.

Blanching orscaldingin water or steam to minimize enzyme actr/ity is a firsr step in the preservation ofvegetables. whether hy heat processing, freezing or dehydrati '. n. The process is carefully controiled, but smali amounts of some minerals and walet soluble ritamins cisso!ve in the water cr steam and are lost.

Heat processing in metal cańs or botthng in glass jars, will reduce the amounts oi heat-sensitive vitamins, especially thiamin, folie acid and vi<amin C. The losses wid depend on the length of time needed to destroy anyjharmfui órganisms, and this will be greater for larger cans and in foods of a close consistency, such as ham, because of the slow transfer of heat from the outside to the centre. They will aiso depend on the ącidity of the food and the presence of light and air; it is therefore diffieult to give precise values for expected losses.

Dehydradon (in air) in carefully controiled conditions has little effect on most nutrients, but about half the vitamin C is lost and there is a complete loss of thiamin ifsulphur dioxideisadded. Prolonged sun drying as in the production of raisins allows suBTtantial changes to occur. Suilable packaging of dried foods is essentiai to prevent nutrient losses during storage.

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