淀粉脱支酶的研究进展及应用

阐述了2种淀粉脱支酶的作用机理,简要综述了2种淀粉脱支酶的类型、研究历史及测定方法、对淀粉粒结构与品质的影响及应用前景。     

异淀粉酶增强红薯粉品质的研究

目的利用异淀粉酶对红薯淀粉改性,研究不同剂量的酶添加量对红薯粉品质的影响。方法测定不同酶添加量相应的直链淀粉的含量,并以红薯粉的糊化特性、凝胶性质、质构性质、烹煮性质以及感官评分作为评价指标,研究了异淀粉酶对红薯粉品质的影响。结果当酶添加量为160U/g(干基质量)时,直链淀粉含量为32.69%,酶添加量继续增加时,直链淀粉含量变化不大;酶添加量120U/g时,淀粉的糊化性质较好;酶添加量达到160 U/g时,样品的凝胶性质、质构性质以及烹煮性质显著增强(P0.05)。酶添加量200 U/g时,样品的口感最好。结论就整体而言, 160 U/g左右的酶添加浓度,能够在节约成本的前提下,显著提升红薯粉的品质。     

酸性异淀粉酶产生菌的筛选及鉴定

从淀粉厂附近的土壤中分离出产脱枝酶的菌株,通过初筛和复筛,得到1株产偏酸性异淀粉酶活力较高的菌株YDF30。其发酵56h时酶活力最大,达到16．4U/mL。所产生的异淀粉酶最适反应温度为55℃,最适pH值为5．2,在低于50℃和pH5．2～9．6条件下较稳定。依据其形态特征和生理生化实验结果,初步鉴定该菌株为芽孢杆菌(Bacillus sp．)。     

异淀粉酶改性玉米淀粉胶囊的研制及性能研究

以玉米淀粉为主料,聚乙烯醇、海藻酸钠、甘油及卡拉胶等为辅料制备异淀粉酶改性玉米淀粉胶囊,并对其吸湿性、崩解性等进行测定。结果表明:经0.2m L 10mg/m L的异淀粉酶处理5min后得到的玉米淀粉在溶胀、糊化等一系列过程中操作可控性增强,改性后溶胶的粘度降低了约42%。通过添加辅料3.0%卡拉胶、0.2g KCl、1.0%甘油、0.5%海藻酸钠及0.2%聚乙烯醇,所得淀粉植物胶成膜性、阻水性及强度均明显增强,相比于明胶胶囊崩解时限缩短。     

Effect of jet-cooking and hydrolyses with amylases on the physicochemical and in vitro digestion performance of whole chickpea flours

Whole chickpea flours were subjected to a pilot plant process aimed to understand the effects of jet-cooking followed by α-amylase or isoamylase hydrolyses in terms of physicochemical and the in vitro digestion performance of starch and proteins. Jet-cooked flours generated lower viscosities and had lower gelatinisation temperatures when compared with their raw counterparts; furthermore, the amylolytic enzymes improved both starch and protein in vitro digestion rates (HI of 85.33 and relative digestion of 88.92%, respectively) that were strongly correlated with the amylose content (P < 0.05). By means of principal component analyses (PCA) is concluded that the changes in granular architecture, reflected by lower ΔH values and new linear structures after isoamylase hydrolysis (treated = 44.36% vs. raw = 26.43%) as well as protein denaturation promoted similar glycemic responses in raw flours compared with jet-cooked counterparts (83.12 and 84.77, respectively). The combination of a thermal-enzymatic method could be a useful alternative to produce novel pulse flours.     

酶法测定葛根支链淀粉分支化度

通过异淀粉酶和普鲁兰酶分别对葛根支链淀粉β 限制糊精进行彻底的脱支水解 ,测得葛根支链淀粉的分支化度为 1 2∶1。 2种酶对脱支反应作用有不同的影响 ,异淀粉酶的酶活对脱支反应的影响较大 ,而普鲁兰酶的酶活影响相对较小。为保证脱支反应进行完全 ,对保温时间进行了研究。结果表明 ,在酶促反应条件下 ,使反应液中的还原力达到一定值 ,对于1mg/mL葛根支链淀粉 β 限制糊精 ,异淀粉酶和普鲁兰酶的用量分别不得少于 1 2U/mL和0 4U/mL ,保温时间分别不得少于 15h和 2 0h。     

Nano-structures of debranched potato starch obtained by isoamylolysis

Starch debranching is fundamental for understanding the structure-function relationships of starch. In this paper, atomic force microscopy (AFM) was used to investigate potato starch by isoamylase [EC 3.2.1.68] debranching at nanometer scale. The hydrolysates were separated by gel-permeation chromatography and the fractions were imaged. In addition to linear structures and branches, coiled structures were revealed in the intermediate hydrolysates. It is concluded that isoamylolysis is very useful for a better understanding of starch structure-property relationships.     

Thermobifida fusca异淀粉酶的作用机制分析

异淀粉酶可水解支链淀粉的α-1,6糖苷键,为淀粉彻底水解所必须。使用仪器分析方法推断此类酶作用机制的研究国内未见报道。Thermobifida fusca异淀粉酶经镍离子亲和色谱纯化,以玉米支链淀粉(maize amylopectin,AP)为底物,结合体积排阻色谱、高效阴离子交换色谱-脉冲安培检测器及氢谱核磁共振等仪器分析方法研究其作用机制。结果表明:AP分子的相对分子质量为2 812 000,水解反应2 h后生成两类葡聚糖组分,相对分子质量分别为760 000和7.2 000,比例为1∶4.4;IAM随机水解支链淀粉分子的α-1,6糖苷键,并可切断带有2-3个葡萄糖残基的侧链分支点生成麦芽糖和麦芽三糖,而对α-1,4糖苷键无作用。完全水解支链淀粉生成具有α或β型还原末端的直链淀粉链或麦芽寡糖,产物聚合度(degree of polymerization,DP)主要在15~35之间。IAM作用机理的研究可为其工业化应用奠定基础。     

响应面试验优化晶种诱导-双酶复合法制备RS_3型籼米抗性淀粉工艺

以微波预糊化籼米淀粉为原料,自制RS_3型马铃薯抗性淀粉为晶种,研究RS_3型籼米抗性淀粉的晶种诱导-双酶复合法制备工艺。利用扫描电子显微镜对淀粉颗粒形貌进行表征并研究淀粉的抗酶解性。在单因素试验的基础上,固定其他酶解条件,以RS_3型籼米抗性淀粉产率为响应值,确定晶种添加量、异淀粉酶添加量、普鲁兰酶添加量和普鲁兰酶酶解时间作为影响产率的主要因素,进行Box-Behnken响应面优化试验。得到RS3型籼米抗性淀粉的最佳制备工艺条件为:晶种添加量5%、异淀粉酶添加量8 U/g、普鲁兰酶添加量8 U/g、普鲁兰酶酶解时间3.50 h。在此最佳制备工艺条件下,RS_3型籼米抗性淀粉产率为27.42%,RS3失去原有的淀粉颗粒形貌,表面变得粗糙,结晶结构致密,具有较强抗酶解能力。     

淀粉球晶的制备及其理化性质

本文以蜡质玉米淀粉为试验原料,采用酶法脱支淀粉后重结晶制备淀粉球晶,通过对所制淀粉球晶的链长分布与分支度、回收率、球晶形貌特征、结晶度分析及热力学性质测定,考察异淀粉酶添加量和结晶时间对球晶理化性质的影响。结果表明:淀粉糊化后冷却至50℃加入25 U/g异淀粉酶反应24 h可使支链淀粉完全脱支,所得淀粉球晶平均链长为26.70;已脱支的淀粉于25℃条件下重结晶,回收率和结晶度随着结晶时间的延长而提高,结晶24 h回收率和结晶度分别为76.58%和51.1%;淀粉球晶的起糊温度(T_o)、峰值温度(T_p)、终止温度(T_c)和焓值(△H)高于原淀粉,且随着结晶时间的延长而呈现增大趋势;SEM图像显示,随着结晶时间的延长,淀粉球晶的颗粒度逐渐清晰,但淀粉球晶颗粒出现聚集现象。