ENH 222 Lecture Notes - Lecture 13: Food Preservation, Microorganism, Freeze-Drying
16 Jul 2018
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Document Summary
Food preservation principles: two general principles are employed in food preservation, inhibition principle, killing principle. Inhibition principle: in this principle, food preservation is achieved by inhibition of growth and multiplication of microorganisms, the inhibition principle can be achieved by any of the following methods: Reduction of water activity - e. g. drying and salting. Reduction in ph - e. g. fermentation and addition of acids. Smoking - which has a drying and preservative effect. Many food products can be preserved by lowering ph so that the growth of spoilage and pathogenic bacteria is prevented. The lowering of ph can be achieved by addition of acids and fermentation. Fermentation is the breakdown of carbohydrates under anaerobic conditions into alcohol or lactic acid and carbon dioxide. Lowering of water activity can be achieved by: addition of high content of salt: sodium chloride and sometimes nitrates and nitrites, addition of high content of sugar, drying: sun/air drying; electrical drying or freeze drying.
