Improving Qualities of Rice Beer Using Enzymes and Amino Acids
2012
Kwon, Y.A., Woosuk University, Wanju, Republic of Korea | Lee, K.G., Dongguk University, Seoul, Republic of Korea | Hong, K.W., Dongguk University, Seoul, Republic of Korea | Lee, S.J., Dongguk University, Seoul, Republic of Korea
Various enzymes and amino acids were used to improve the quality attributes of beer brewed with rice adjunct. Alpha-amylase was applied to make more saccharification during the malting stage. Protease and amino acids, such as lysine, glutamic acid, and proline, were added prior to fermentation stage and the qualities of beer such as Brix, reducing sugar content, pH, and viscosity of the wort, were evaluated. The changes in the alcohol content, bubble stability, bitterness, and color of the beer were also investigated. Results showed that Brix, reducing sugar content, and viscosity of the wort were reduced, while the pH was increased in proportion to the rice powder content. It revealed that the liquefaction rate was decreased as the content of rice powder was increased. But the liquefaction rate was recovered by the addition of α-amylase. The alcohol content and bubble stability of beer were decreased while its bitterness and yellowness were increased in proportion to the rice powder content. While alcohol content, bitterness, and yellowness were recovered by the addition of protease, the bubble stability was reduced in spite of the use of protease. Other characteristics of the beer except yellowness color were recovered by the addition of glutamic acid. However, when lysine and proline were used, alcohol content and bitterness were recovered. The bubble stability and the turbidity of the beer were not improved although the amino acids were used. The rice beer quality was thus improved by the addition of amylase, followed by glutamic acid and protease.
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