乙醇对谷朊粉酶解产物的苦味影响研究

为了探寻降低谷朊粉酶解产物苦味的方法,通过添加不同浓度的乙醇(5%、10%和15%),研究其对碱性蛋白酶酶解产物苦味值、游离氨基酸和相对分子质量分布的影响,以及在乙醇存在下碱性蛋白酶、中性蛋白酶以及风味蛋白酶3种复配酶解体系所制得的酶解产物的苦味值和相对分子质量分布变化。结果表明:加入乙醇后,在相同的水解度下(DH),碱性蛋白酶的酶解产物苦味值降低,并与加入乙醇的浓度呈负相关。添加乙醇后,相对分子质量小于1 000的组分含量显著(P0.05)降低,游离疏水性氨基酸(Pro,Ile,Phe和Met)显著(P0.05)增加。添加乙醇后,3种复配酶解体系酶解产物苦味降低,相对分子质量小于1 000的组分含量显著(P0.05)降低。与添加碱性蛋白酶单一酶解相比,在相同的水解度下3种酶复配酶解产物的苦味值进一步降低。添加低浓度乙醇对3种酶的活性影响较小。

Effects of ethanol on debittering of wheat gluten hydrolysates

To explore the way to debitter wheat gluten hydrolysates, different concentration of ethanol (5%, 10% and 15%) were added during hydrolysis process. The changes of free amino acid, molecular weight distribution and bitterness value of hydrolysates produced by Alcalase was studied. Furthermore, the changes of molecular weight distribution and bitterness value of hydrolysates produced by the combination of Alcalase, neutral protease and flavourzyme was also measured. The results showed that: at the same degree of hydrolysis (DH), hydrolysates produced by Alcalase showed less bitterness after adding ethanol. The bitterness value had negative correlation with the ethanol concentration. The content of protein (molecular weight<1 000) was significant (P<0.05) decreased and free hydrophobic amino acids (Ile, Pro, Phe and Met) were increased (P<0.05) in ethanol groups. Hydrolysates produced by combination of three kinds of enzymes showed less bitterness value and the content of protein (MW<1 000) was significant (P<0.05) decreased in ethanol groups. The bitterness of hydrolysates produced by the combination of enzymes showed less value than Alcalase at the same DH. Low concentration of ethanol had less effect on the enzyme activity.