BIOS 2210 Lecture 5: Preserving Food
26 Sep 2018
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Fermentation by bacteria and yeast (eukaryote) = foods. Butanol: home brewing, malting of barley: grain is soaked to germinate. Seed coats produce hydrolases: mashing: malt undergoes stepwise heating, or mashing. Hydrolases break down prot and starch to components that yeast can ferment. Mash is filtered; now called wort: wort boiling: wort is boiled with hops for flavor. Partial aeration occurs: fermentation: yeast is added in fermentation vessel. Yeast ferments sugars to ethanol n protein d wort. d to sterilize: ethanol, fermentation: yeast is added in fermentation vessel. By-products of amino acid synthesis generate higher alcohols, esters, and sulfur compounds that add flavor: post-fermentation treatments: secondary fermentation removed aldehyde and othe undesirable by-products. Bacteria make sour beer, yeast make alcohol and o2: bread, yogurt and kimchi. Lactic acid fermentation: physical control of microbes. Heat can kill microbes by altering their membranes and denaturing proteins.
