玉米淀粉浓度对酶法制备直链麦芽低聚糖的影响

Effects of corn starch concentration on enzymatic preparation of linear malto-oligosaccharides

为研究浓度对玉米淀粉酶解过程和产物的影响,以直链麦芽低聚糖含量和产率为指标,探究了直链麦芽低聚糖生成酶(Bst-MFA酶)对不同浓度(质量分数)玉米淀粉的酶解过程,并对相关机理进行了分析。结果表明,玉米淀粉质量分数由10%提高至50%时,酶解24h后直链麦芽低聚糖和主产物麦芽五糖、麦芽六糖的含量均呈现逐渐升高的趋势,且二者均在45%的底物质量分数时达到最大值,分别为344.47和192.33mg/g;而直链麦芽低聚糖的产率逐渐降低。其主要原因可能是:随底物浓度的增加,液化和糖化过程中体系黏度增大,水分子运动性降低,体系中自由水明显减少,且酶在不同浓度玉米淀粉中的作用模式存在差异,使得高浓度条件下其对玉米淀粉的水解作用不够充分,直链麦芽低聚糖的产率呈下降趋势。该研究可为工业生产中直链麦芽低聚糖的酶法制备提供参考依据。

Linear malto-oligosaccharides can be produced from corn starches by malto-oligosaccharides-forming amylase(Bst-MFAse).This study aimed to evaluate the effects of initial substrate concentration on producing linear malto-oligosaccharides by Bst-MFAse using the contents and yields of linear malto-oligosaccharides as indicators,followed by analyzing related mechanisms.The results showed that when the initial concentration of corn starch increased from 10%to 50%(w/w),the contents of linear malto-oligosaccharides and main products(maltopentaose and maltohexaose)increased gradually after hydrolyzing for 24 h.Besides,their contents reached the highest with 45%substrate,which were 344.47 and 192.33 mg/g,respectively.However,the yield of linear malto-oligosaccharides decreased gradually.This might be due to the increased substrate concentration enhanced the viscosity of the system during liquefaction and saccharification,which resulted in decreased water molecule mobility and significantly reduced free water amount.Additionally,MFAse had different action modes among different concentrations of corn starches,which could cause insufficient hydrolysis of corn starch molecules at high concentration.Overall,this study provides a reference for enzymatic preparation of linear malto-oligosaccharides in industries.