title: Effect of initial ph on growth characteristics and fermentation properties of Saccharomyces cerevisiae.
abstract: As the core microorganism of wine making, Saccharomyces cerevisiae encounter low pH stress at the beginning of fermentation. Effect of initial pH (4.50, 3.00, 2.75, 2.50) on growth and fermentation performance of 3 S. cerevisiae strains Freddo, BH8, Nº.7303, different tolerance at low pH, chosen from 12 strains, was studied. The values of yeast growth (OD600 , colony forming units, cell dry weight), fermentation efficiency (accumulated mass loss, change of total sugar concentration), and fermentation products (ethanol, glycerol, acetic acid, and l-succinic acid) at different pH stress were measured. The results showed that the initial pH of must was a vital factor influencing yeast growth and alcoholic fermentation. Among the 3 strains, strain Freddo and BH8 were more tolerant than Nº.7303, so they were affected slighter than the latter. Among the 4 pH values, all the 3 strains showed adaptation even at pH 2.50; pH 2.75 and 2.50 had more vital effect on yeast growth and fermentation products in contrast with pH 4.50 and 3.00. In general, low initial pH showed the properties of prolonging yeast lag phase, affecting accumulated mass loss, changing the consumption rate of total sugar, increasing final content of acetic acid and glycerol, and decreasing final content of ethanol and l- succinic acid, except some special cases. Based on this study, the effect of low pH on wine products would be better understood and the tolerance mechanism of low pH of S. cerevisiae could be better explored in future.
authors.affiliation: College of Food Science & Nutritional Engineering, China Agricultural Univ, 100083, Beijing, China; College of Food Science, Sichuan Agricultural Univ, 625000, Sichuan Ya'an, China.
authors.forename: Xingyan
authors.initials: X
authors.lastname: Liu
authors.forename: Bo
authors.initials: B
authors.lastname: Jia
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Sun
authors.forename: Jingya
authors.initials: J
authors.lastname: Ai
authors.forename: Lihua
authors.initials: L
authors.lastname: Wang
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.forename: Fang
authors.initials: F
authors.lastname: Zhao
authors.forename: Jicheng
authors.initials: J
authors.lastname: Zhan
authors.forename: Weidong
authors.initials: W
authors.lastname: Huang
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012441:Saccharomyces cerevisiae / Q000254:growth & development* / Q000378:metabolism; D019802:Succinic Acid / Q000378:metabolism; D014920:Wine / Q000032:analysis*
chemical_list: D000431:Ethanol; D019802:Succinic Acid; D005990:Glycerol; D019342:Acetic Acid
keywords: Fermentation; Saccharomyces cerevisiae; growth; initial pH