BIOL 1011 Lecture : Control Of Microbial Growth Notes- BRININSTOOL
Document Summary
1822-1895 louis pasteur: disproved spontaneous generation the hypothesis that living organisms can originate from nonliving matter. Pasteurization: reduces microbial load, kills most pathogens and inhibits growth of spoilage microorganisms liquids and wet foods, 71 c, 15 sec (flash pasteurization, heat most widely used method of sterilization. Sterilization- killing of all organisms: radiation, filtration, cold (gas, 2-4 used to sterilize heat sensitive materials. Endospores (high content of small acid soluble proteins and low water content: acidic foods easier to sterilze/pasteurize, high sugar, protein, and fat concentrations increase heat resistance. Radiation sterilization: controlled doses of radiation inhibit or kill microbial growth. Ionizing radiation: x-rays and gamma rays sterilize by inducing mutations via breaks in covalent bonds of biological molecules. Ultraviolet radiation: 254nm is germicidal, causes thymine dimers in dna, cannot penetrate solids, used to decontaminate surfaces, air and water laminar flow uv hood . It is produced artificially by neutron activation of co59.
