Hu, S., Tsingtao Brewery Co. Ltd., Qingdao, CHINA
Poster
Free amino acid (FAN) has been regarded as an important index to predict yeast fermentation and beer quality. Amino acid utilization by yeast during brewer’s wort fermentation is seen as linked to flavor profile, thus the amino acid spectrum of wort also had a large impact on yeast flavor and beer quality. Here, the influences of malting barley variety and malt modification on wort amino acid spectrum were investigated. Fifty commercial malts from Canada, Australia and China were mashed using the Congress mashing protocol, and the amino acid composition of wort was analyzed. Principal component analysis showed a significant difference between malts from different regions and the malt from Canada close to that from Australia. Although no obvious difference was found in total amino acids level, relative proportions of individual amino acids were remarkably different. Malts from China were rich in B group amino acids and that from Canada and Australia were abundant in C group amino acids and proline. Furthermore, the effect of malt modification (Kolbach index [KI] 33–53) on the amino acid spectrum was investigated. Results showed that the total amino acids level was enhanced with the increase of KI. However, the changes in relative proportions of individual amino acids were different. The proportion of histidine and proline decreased with increased KI. While the proportion of tyrosine, threonine, leucine, phenylalanine and isoleucine were enhanced with increased KI. In conclusion, this research on the factors influencing wort amino acids spectrum allows brewers to keep better control of wort FAN according to malt blending and malting process, leading to a steady wort composition.
