MIC 320 Lecture 3: Lecture 3 Part 1
27 Oct 2016
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Lecture 4: intrinsic and extrinsic parameter of foods that affect microbial growth. What are the factors affecting microbial growth: intrinsic parameters - an inherent part of the tissues. Most microorganisms grow well at (6. 6-7. 5) neutral ph. A few could grow below ph 4. Acid tolerance: pathogenic bacteria < most bacteria < molds and yeasts. Ph requirement of each organism also depends on other growth factors: e. g. salt concentration and temperature. Definition of low acid food ph is based on this organism. Which bacteria cannot grow in foods with ph. Ph of meat is determined by the glycogen content at the time of death: during aging/tenderization (10- Is low ph (~ 5. 1) desirable in beef: extend shelf life, lower ph helps break down. Protein peptides, amino acids: water holding capacity increased, buffering capacity of foods. High protein foods have higher buffering capacity. Vegetable changes ph easily with salad dressing: ph effect on microorganisms. Denature enzymes that are important for cellular functions.
