脂肪酶对麦秸亲脂类抽提物的影响

Effect of lipases on lipophilic extractives of wheat straw

研究了脂肪酶对麦秸中亲脂类抽提物的去除规律及该酶对乙酰化度和麦秸刨花板内结合强度的影响,同时通过气相色谱-质谱(GC-MS)分析,比较了酶处理前后麦秸正己烷抽提物组成的变化。结果表明:脂肪酶处理麦秸时,最适pH为7.5,温度50℃,适宜的酶用量为7.5×10-3mol/(min·g)(以干麦秸计),处理时间8h,在此条件下,亲脂类抽提物去除率为62%。脂肪酶处理增加了麦秸表面的羟基浓度,使麦秸刨花板的内结合强度提高4.5倍。脂肪酶对麦秸正己烷提取物主要成分脂肪酸、蜡质和类固醇的去除率分别为79.67%、69.04%和41.47%;另外,抽提物中含有少量的甘油酯、脂肪醇、硅氧化物和酚类化合物,脂肪酶对它们的去除率分别为80.98%、63.30%、43.31%和36.35%。脂肪酶可去除麦秸表面的亲脂类提取物,提高麦秸表面的羟基浓度,提高麦秸刨花板的力学性能。

Effects of treatment conditions such as pH,enzyme dosage,time and temperature were investigated on the removal of lipophilic extractives from wheat straw （WS） using Candida cylindracea lipases. The influences of lipase treatment on WS weight gain percent from acetylation and the inner bonding strength of WS particle board were also examined. The WS lipophilic extractives were analyzed by GC-MS. Test results showed that the removal rate of lipophilic extractives was 62 % under the optimal conditions： 50 ℃,pH 7. 5,lipase dosage 7. 5 × 10-3 mol/（min·g）（based on oven-dried WS）,time 8 h. The inner bonding strength of particle board manufactured from the treated WS could increase by 4. 5 fold due to the increase in —OH concentration on the WS surface. The GC-MS results showed the main components of n-hexane extractives of WS were fatty acids,waxes and steroids,and their removal rates by lipases were 79. 67 % ,69. 04 % and 41. 47 % ,respectively. There were some glycerides,fatty alcohols ,silicon oxide and phenolics in the extractives,and their removal rates by lipases were 80. 98 % ,63. 30 % ,43. 31 % and 36. 35 % ,respectively. It was concluded that the removal of the lipophilic extractives from the WS by lipases could increase the hydroxyl group concentration and the mechanic performance of WS particle board.