MIP 300 Lecture Notes - Pediococcus, Microbiological Culture, Gram Staining
26 Jun 2014
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Document Summary
Maintain pure cultures that may be used for fermentations. Propagate yeast to keep fermentations consistent and clean of contamination. A single strain of a yeast species grown in isolation from other yeast strains and free from any microbiological (e. g. bacterial) contaminants. Pure yeast cultures can be isolated as individual colonies (streak plating) To produce sufficient yeast in good physiological condition. Prevent problems (sluggish fermentations, off flavors like h2s/diacetyl, maltotriose uptake, altered flocculation patterns) At new belgium, ale yeast is typically repitched for generations, and lager yeast for up to 5 generations before a new propagation. Finally the propagation is moved to a bbl keg. Propagations stepped up at maximum 1:10 volume increments. Hops are naturally antimicrobial (some species of lactobacillus are tolerant) Most commonly found lactobacillus species at nbb: brevis, casei, paracasei. All of these species produce lactic acid and possibly diacetyl (l. casei). The most common off flavor will be sour.
