MICR-4070 Lecture Notes - Lecture 16: Radiation Resistance, Streptococcus, Micrococcus
22 Mar 2018
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Micr 4070: food and dairy microbiology, test 2 (lecture 7, modified atmosphere packaging) Extended shelf life, but pathogens have more time to grow. Reduced oxygen levels favors the growth of anaerobic or microaerophilic pathogens. Temperature abuse will allow growth of m/o inhibited by low temperature or co2. Pathogens of concern: l. monocytogenes, c. botulinum. Sachet generator: oxygen absorbents: additional means of lowering residual oxygen content. These products scavenge oxygen to less than 100 ppm: most employ finely divided iron powder. Fe(oh) 2 + 1/2o2 + 1/2h2o -> fe(oh)3. Ethanol gas generators: when food is packaged with water vapor, it can penetrate the sachet containing food grade ethanol (50%, w/w) absorbed into silicon dioxide powder. Water releases ethanol from its encapsulation and permeates the head space. Its primary use is on high moisture bakery products. Defintion of ionizing radiation: electromagnetic radiation: causes ejection of electrons & formation of ion pairs:
