酿造过程对麦汁蛋白及其氧化特性的影响

Effect of Brewing Process on Wort Protein and Its Oxidative Characteristics

摘要:

本文研究了啤酒酿造过程尤其是糖化工艺对麦汁蛋白质含量、游离巯基含量和抗氧化活性的影响。研究结果表明：糖化过程伴随着大分子蛋白质的降解和小分子蛋白质的形成，蛋白质和游离巯基含量均呈现先上升后下降的规律；经历糖化阶段，蛋白质含量从310.63 μg/mL降至229.18 μg/mL，游离巯基含量则从0.61 μmol/g降至0.04 μmol/g，分别下降了26.22%和93.44%，这说明糖化是蛋白质和游离巯基发生关键变化的重要阶段。麦汁的蛋白质含量、游离巯基含量与ABTS自由基清除活性间呈极显著的正相关（p<0.01），适当延长糖化时间和提高糖化温度有利于麦汁蛋白及其它具有抗氧化活性物质的溶出与积累，从而显著提高了麦汁的ABTS自由基清除活性。因此，麦汁蛋白尤其是具有抗氧化活性的脂转移蛋白1（LTP1）对麦汁的氧化稳定性具有重要贡献。

Abstract:

The effects of beer brewing process, especially mashing process on protein content, free thiol groups content and antioxidant activity of wort were examined. The results showed that the degradation of macromolecular proteins was accompanied by the formation of protein with low molecular weight during mashing. Protein and free thiol groups contents showed a pattern of increasing first and then decreasing, and both of them decreased from 310.63 μg/mL to 229.18 μg/mL, and from 0.61 μmol/g to 0.04 μmol/g, with the reduction of 26.22% and 93.44%, respectively after mashing, which indicated that mashing was an important stage in the key changes of protein and thiol groups. There were significant (p<0.01) positive correlations among protein content, free thiol groups content and ABTS free radical scavenging activity. Extension of the mashing time and increase of mashing temperature were beneficial to the dissolution and accumulation of protein in wort, which significantly improved the ABTS free radical scavenging activity, and increased the color and TBA of wort. Therefore, the protein in wort, especially lipid transfer protein 1 (LTP1) with antioxidant activity, had a positive effect on the oxidative stability of wort.