| Title: | Effects of wort gravity and nitrogen level on fermentation performance of brewer's yeast and the formation of flavor volatiles |
| Author(s): | Lei H; Zhao H; Yu Z; Zhao M; |
| Address: | "College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510640, China" |
| DOI: | 10.1007/s12010-012-9560-8 |
| ISSN/ISBN: | 1559-0291 (Electronic) 0273-2289 (Linking) |
| Abstract: | "Normal gravity wort and high gravity wort with different nitrogen levels were used to examine their effects on the fermentation performance of brewer's yeast and the formation of flavor volatiles. Results showed that both the wort gravity and nitrogen level had significant impacts on the growth rate, viability, flocculation, and gene expression of brewer's yeast and the levels of flavor volatiles. The sugar (glucose, maltose, and maltotriose) consumption rates and net cell growth decreased when high gravity worts were used, while these increased with increasing nitrogen level. Moreover, high gravity resulted in lower expression levels of ATF1, BAP2, BAT1, HSP12, and TDH, whereas the higher nitrogen level caused higher expression levels for these genes. Furthermore, the lower nitrogen level resulted in increases in the levels of higher alcohols and esters at high wort gravity. All these results demonstrated that yeast physiology and flavor balance during beer brewing were significantly affected by the wort gravity and nitrogen level" |
| Keywords: | "Amino Acids/metabolism Beer/microbiology Carbohydrate Metabolism Colony Count, Microbial Esters/metabolism Ethanol/metabolism *Fermentation Flavoring Agents/*metabolism Gene Expression Regulation, Fungal Genes, Fungal Gravitation Nitrogen/*metabolism Prot;" |
| Notes: | "MedlineLei, Hongjie Zhao, Haifeng Yu, Zhimin Zhao, Mouming eng Research Support, Non-U.S. Gov't 2012/01/28 Appl Biochem Biotechnol. 2012 Mar; 166(6):1562-74. doi: 10.1007/s12010-012-9560-8. Epub 2012 Jan 27" |
