title: Influence of freeze-drying conditions on survival of Oenococcus oeni for malolactic fermentation.
abstract: Malolactic fermentation (MLF) is an important process in wine production. Oenococcus oeni is most often responsible for MLF. Starter culture technology, involving the inoculation of O. oeni into wines, has been developed for inducing MLF. In this study, the effects of cell washing, pH of suspension medium, preincubation in sodium glutamate, initial cell concentration and freezing temperature on viability of freeze-dried O. oeni H-2 were investigated. The cell viability of samples without washing with potassium phosphate buffer was significantly lower than those samples undergone washing. When pH of suspension medium was 7.0 the cell survival was the highest. The cell viability was enhanced when the cells were preincubated at 25 degrees C before freezing. When 2.5% sodium glutamate was used as protective agent in suspension medium, the optimal initial cell concentration was 10(9) CFU/ml. The cell viability increased by 21.6% as freezing temperature decreased from -20 degrees C to -65 degrees C. However, when the cells were frozen in liquid nitrogen (-196 degrees C), the cell survival significantly decreased.
authors.affiliation: Hebei University of Science and Technology, Shijiazhuang, 050018, China. gqzhao18@126.com
authors.forename: Guoqun
authors.initials: G
authors.lastname: Zhao
authors.forename: Gui
authors.initials: G
authors.lastname: Zhang
mesh_terms: D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry; D005285:Fermentation; D005503:Food Additives / Q000494:pharmacology; D005516:Food Microbiology; D005612:Freeze Drying; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism*; D007934:Leuconostoc / Q000254:growth & development* / Q000378:metabolism*; D008293:Malates / Q000378:metabolism*; D050296:Microbial Viability; D012970:Sodium Glutamate / Q000494:pharmacology; D014920:Wine / Q000382:microbiology*
chemical_list: D003470:Culture Media; D005503:Food Additives; D008293:Malates; D019344:Lactic Acid; C030298:malic acid; D012970:Sodium Glutamate