Graduate Thesis Or Dissertation
 

Characterization of Oregon-derived malo-lactic bacteria : fermentation properties and storage stability

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/1831cp05f

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  • Gram positive cocci isolated from Oregon wines were characterized and their relative malate fermentation abilities compared. They were heterofermentative, catalase negative, and facultatively anaerobic. Glucose, fructose, cellobiose, maltose, ribose, trehalose, salicin and esculin were fermented by all strains. Arabinose was fermented weakly but lactose, raffinose, sucrose, xylose, rhamnose, mannose and glycerol were not fermented. Dextran was not produced from sucrose nor ammonia from arginine. The isolates grew well in a tomato/vegetable juice medium and fermented malate to lactate as detected by chromatography. Optimum growth temperatures ranged between 28 and 31 °C and generation times between 5.2 and 18.7 were observed at pH 5.5. The PH optimum ranged between 4.5 and 5.75. Growth was obtained in artificial media containing 14% ethanol and at pH values lower than 3.3. These malo-lactic bacteria were considered to be strains of Leuconostoc oenos. Malate fermentation rates indicated that these isolates effected a more rapid and complete malo-lactic fermentation than reference Leuconostoc strains. This was found in both artificial media at pH 3.5 and in Pinot Noir wine, pH 3.45. Levels of 30 ppm free sulfur dioxide and 0.6 g/L fumaric acid were observed to inhibit growth. Stability of cryopreserved cultures were studied over extended storage. Following 3 months storage of frozen concentrates at -20 and -40°C, survival rates of 70 to 80% were achieved using a modified Rogosa medium plus 15% glycerol. Following 2 months storage of lyophilized concentrates at room temperature, survival rates of 35 to 60% were achieved in milk (11% solids).
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