壳聚糖—戊二醛固定化木聚糖酶的技术研究

采用壳聚糖微球一戊二醛交联的方法固定木聚糖酶,探讨壳聚糖浓度、戊二醛体积分数和交联时间对固定化酶相对酶活力的影响.以正交试验确定木聚糖酶的最佳固定化条件,比较固定化酶与其游离酶的最适反应pH值、pH值稳定性、最适反应温度及热稳定性.结果表明,在壳聚糖质量浓度0.1g/mL、戊二醛添加量3％、给酶量2000U/g载体、交联时间2.5h时,固定化酶的回收率较高,可达到65.38％,同时固定化和游离酶的最适温度分别为60℃、55℃,最适pH值分别为4.5、5.0,热稳定性有不同程度的提高,pH稳定性两者变化不大.木聚糖酶的固定化能有效地提高其作用性能,从而为木聚糖酶的工业化应用提供了一定的理论依据.     

Optimization of peptic hydrolysis parameters for the production of angiotensin I-converting enzyme inhibitory hydrolysate from Acetes chinensis through Plackett-Burman and response surface methodological approaches

BACKGROUND: Angiotensin I‐converting enzyme (ACE) plays an important physiological role in regulating blood pressure. The elevation of blood pressure could be suppressed by inhibiting ACE. ACE inhibitory peptides derived from food proteins could exert antihypertensive effects without side effects. Acetes chinensis is a marine shrimp suitable for the production of ACE inhibitory peptides. The principal objective of this study was to screen for the significant variables, and further to optimize the levels of the selected variables, for the enzymatic production of ACE inhibitory peptides from Acetes chinensis. RESULTS: Plackett–Burman design and response surface methodology were employed to optimize the peptic hydrolysis parameters of Acetes chinensis to obtain a hydrolysate with potent ACE inhibitory activity. The peptic hydrolysis variables were subject to a Plackett–Burman design for screening the main factors. The selected significant parameters such as pH, hydrolysis temperature and enzyme/substrate (E/S) ratio were further optimized using a central composite design. The optimized conditions were: pH 2.5, hydrolysis temperature 45 °C, E/S ratio 17 800 U kg^?1 shrimp and substrate concentration 200 g L^?1. The results showed that 3–5 h hydrolysis could result in a hydrolysate with ACE inhibition IC₅₀ of 1.17 mg mL^?1 and a high DH of 25–27%. CONCLUSION: Plackett–Burman design and RSM performed well in the optimization of peptic hydrolysis parameters of Acetes chinensis to produce hydrolysate with ACE inhibitory activity. A hydrolysate with potent ACE inhibitory activity and high degree of hydrolysis was obtained, so that the yield of ACE inhibitory peptides in it was high. Copyright © 2011 Society of Chemical Industry     

天然彩棉织物生态整理工艺探讨

本文探讨了棕色天然彩色棉织物生物酶处理的生态整理工艺,解决了常规的前处理工艺中彩棉色光不稳定、强力损伤大的现象,同时提高了织物的去杂效果。     

高品质红薯渣在面条中应用的研究

采用单因素实验和正交实验相结合的方法,研究高品质红薯渣面条的加工工艺。结果显示,产品的最佳工艺为:纤维素酶处理红薯渣、红薯渣的添加量为11%、海藻酸钠的添加量为0.35%、食盐的添加量为0.25%,在此工艺条件下,产品的烹煮损失率为8.77%,断条率为0。     

降解南瓜纤维素菌株的分离筛选及酶活测定

目的:筛选出能高效降解南瓜纤维素的菌株,以制备南瓜可溶性膳食纤维。方法:从土壤、腐烂的树叶和水果上分离出具有降解南瓜纤维素的菌株,用刚果红染色透明水解圈进行初筛,然后用CMC-Na、滤纸和南瓜渣为碳源测所有菌株及混合菌株的羧甲基纤维素酶活力,最终选出1株酶活力较高菌株进行下一步实验。结果:共分离到能够有效降解纤维素的共有5株细菌和7株真菌,通过测单菌株和混合菌株的酶活力,表明混合菌株的酶活力最大值比单菌株的酶活力最大值要高3倍之多。结论:混合菌株的酶活力比单株菌酶活力值高,发酵培养72h南瓜渣可溶性多糖降解力最强。     

几种脱墨助剂与生物酶协同使用效果的比较

生物酶协同脱墨助剂对废新闻纸进行脱墨,并对化学脱墨和生物酶协同脱墨进行比较。结果表明:脱墨助剂B的脱墨效果较好,生物酶协同脱墨浆与化学脱墨浆相比具有较高的白度、物理强度和得率。     

新鲜马铃薯渣同时制备膳食纤维和蛋白的研究

马铃薯渣是马铃薯淀粉生产过程中产生的一种主要成分是水、细胞碎片和残余淀粉颗粒的副产物,含有大量的淀粉和膳食纤维以及少量蛋白质,实际上是一种宝贵的资源。本文采用α-淀粉酶和糖化酶处理马铃薯渣,分离出的液态部分再经发酵培养出可供食用的蛋白质,固体部分经漂白、改性后成为膳食纤维,薯渣得到全利用。设计了工艺流程,对酶的选择和工艺条件作了优化。测定了产物蛋白质和膳食纤维的理化指标。     

源于马铃薯的多酚氧化酶活性中心必需基团组成与抑制机理

探讨源于马铃薯多酚氧化酶(PPO)的酶活性中心必需基团组成与抑制剂对PPO的抑制作用类型。应用具有相对专一性的氨基酸基团化学修饰剂溴乙酸(BrAC)、乙酰丙酮(Hacac)、N-溴代琥珀酰亚胺(NBS)、1,4-二硫代苏糖醇(DTT)与对氯汞苯甲酸(pCMB)等对PPO进行化学修饰反应,确定源于马铃薯的多酚氧化酶活性中心必需基团组成为组氨酸(His)的咪唑基、精氨酸(Arg)的胍基与色氨酸(Trp)残基,二硫键对酶活性中心的稳定有贡献作用但游离的硫基不是酶反应所必需的基团。抑制动力学实验表明乙醇对PPO的半抑制浓度(IC50)为0.12 mmol/L,抑制类型为竞争性可逆抑制,苯甲酸对PPO的IC50为0.07 mmol/L,抑制类型为非竞争性可逆抑制。说明乙醇通过与PPO酶活中心结合抑制PPO酶活性而苯甲酸则通过与PPO非酶活中心的结合抑制PPO酶活。