MICR-4070 Lecture Notes - Lecture 19: Nisin, Antibiotics, Propylene Oxide
23 Mar 2018
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Document Summary
Micr 4070: food and dairy microbiology: test 2 (lecture 10, preservation by chemicals and food. Used since ancient times: most safe food preservative. These chemicals exert a drying effect on both microorganisms and food products: reduces the aw of foods. Microorganisms of concern: halophiles, halodurics, osmophiles, osmodurics: osmophiles like high osmotic pressure that results from sugar additions, halophiles like 2-5% salt conditions; moderate halophiles like 5-20% salt content, and extreme halophiles like 20-30% salt. Used to preserve meat, fish, cakes, pie, condensed milk, and fruit preservatives. A 14,600-da enzyme present in avian eggs, mammalian milk, and tears: eggs are the main source. Optimum temperature for the activity of enzyme is 55-60 c. Destruction of the peptidoglycan of bacterial cell walls: it breaks down the bonds between the peptidoglycan. 1: edta will target g (-) bacteria because it can bind to magnesium and calcium.
