酶解马铃薯淀粉制备脂肪模拟品的研究

利用马铃薯淀粉制备酶变性淀粉,在单因素试验的基础上选择了淀粉浆浓度、酶解温度、酶解时进行三素三水平的正交试验,确定了较优的淀粉酶解工艺条件,使酶解淀粉的DE值稍大于2。再确定酶变性淀粉的糊化温度和糊化时间,制备用采模拟油脂的变性淀粉,以减少食用者的热量摄入,更加有利于人体健康。     

Purification and enzymatic identification of an acid stable and thermostable α‐amylase from Rhizopus microsporus

Rhizopus microsporus, recently isolated from a solid culture of Heng‐Shui Lao‐Bai‐Gan (HSLBG, a famous distilled liquor in Northern China) was found to produce a novel extracellular acid stable and thermostable α‐amylase. This fungal α‐amylase was purified using ammonium precipitation, Sephadex G‐25 desalination and DEAE‐52 cellulose chromatography. Its molecular weight was estimated to be 75 kDa by SDS–PAGE. The optimum pH and temperature of this enzyme was pH 5.0 and 70°C respectively. Thermostability and kinetic analysis through the Arrhenius and Michaelis–Menten equations revealed that this enzyme showed an exceptional activity at low pH and high temperature. A combination of this thermostability and acid stability could be a valuable trait for the efficient hydrolysis of amylose to glucose in large‐scale biotechnology applications. Copyright © 2012 The Institute of Brewing & Distilling     

α‐Amylase inhibitors from an Indonesian medicinal herb,Phyllanthus urinaria

BACKGROUND: Diabetes mellitus and associated diseases are an increasing problem around the world. One of the hyperglycemic remedies is glucose absorption reduction by suppressing carbohydrate digestion due to utilization of α‐amylase inhibitors. RESULTS: Prospective herbs were analyzed by in vitro enzyme assay to evaluate their inhibitory activity against porcine pancreatic amylase (PPA), and it was found that Phyllanthus urinaria and three other herbs to showed a potent inhibitory activity. A 50% aqueous methanol‐soluble extract of the leaves of P. urinaria was chromatographed using a silica gel column. The active fractions were further purified by preparative high‐performance liquid chromatography to isolate active principles against PPA. Structural determination revealed that these isolated compounds were gallic acid, corilagin, and macatannin B, and showed mild activity against PPA (activity in 1 mmol L^?1 concentration: 23%, 21%, 33%, respectively). CONCLUSION: P. urinaria extracts show inhibitory activity against PPA. This activity, together with the information on isolated compounds, may benefit further exploration of P. urinaria utilization in the management of borderline diabetes patients. Copyright © 2011 Society of Chemical Industry     

Combinations of glucose oxidase, α‐amylase and xylanase affect dough properties and bread quality

The objective of this work was to study the effects of the combination of glucose oxidase (Gox), α‐amylase (AM) and xylanase (Xyl) on dough properties and bread quality, applying response surface analysis. Gox improved dough stickiness and bread crumb uniformity, but had a negative effect on specific volume. A positive synergist effect was observed combining Xyl and AM on specific volume and crumb firmness but this synergist effect was negative on crumb uniformity. Using the ‘desirability function’, two optimal formulations for the baking process were obtained. In the first optimisation, the combination of Gox 0.0026, Xyl 0.016 and AM 0.01 g per 100 g of flour will allow to obtain breads with high specific volume and low firmness. Second optimisation (Gox 0.0037, Xyl 0.0089 and AM 0.0105 g per 100 g of flour) will allow to obtain breads with 37% higher specific volume than control and, additionally, with low dough stickiness.     

黑曲霉固态发酵橘皮生产纤维素酶及淀粉酶

以橘皮为原料,以黑曲霉AS3.3928为生产菌株,采用固态发酵法生产纤维素酶和淀粉酶。通过单因素试验考察固态发酵培养基中橘皮含量、培养基含水量、接种量及发酵时间4个因素对纤维素酶和淀粉酶活力的影响。在单因素试验基础上,通过正交试验最终确定最优产酶条件为：固态发酵培养基中添加16g橘皮,并加入5mL无菌水使培养基初始含水量为64mL/100g,黑曲霉接种量15%,发酵60h。在此发酵条件下所产纤维素酶活力可达1816U/g,淀粉酶活力达196U/g。结果表明,利用黑曲霉固态发酵橘皮,非常有利于纤维素酶和淀粉酶的生产。     

Rapid isolation of geraniin from Nephelium lappaceum rind waste and its anti-hyperglycemic activity

Recently we confirmed the ability of ethanolic Nephelium lappaceum L. rind extract to act as anti-hyperglycemic agent. Geraniin, an ellagitannin, was identified as the major bioactive compound isolated from the ethanolic Nephelium lappaceum L. rind extract. In this study, we describe the rapid isolation of geraniin from the above plant. In addition to its extremely high anti-oxidant activity and low pro-oxidant capability, geraniin is seen to possess in vitro hypoglycemic activity (alpha-glucosidase inhibition: IC₅₀ = 0.92 μg/ml and alpha-amylase inhibition: IC₅₀ = 0.93 μg/ml), aldol reductase inhibition activity (IC₅₀ = 7 μg/ml) and has the ability to prevent the formation of advanced glycation end-products (AGE). Geraniin was observed to exhibit these properties at more significant levels compared to the positive controls acarbose (carbohydrate hydrolysis inhibitor), quercetin (aldol reductase inhibitor) and green tea (AGE inhibitor). Geraniin therefore, has the potential to be developed into an anti-hyperglycemic agent. Our findings also strongly support the use of a geraniin-standardised N. lappaceum extract in the management of hyperglycemia.     

双波长法测定南瓜中直链与支链淀粉含量

为建立同时测定南瓜中直链和支链淀粉的双波长比色法。本文采用正丁醇结晶法分离纯化南瓜中直链和支链淀粉并测定其含量。结果表明,分离纯化得到的直链和支链淀粉蓝值分别为0.874和0.196;根据双波长原理和扫描谱图,确定其测定波长为645、565 nm,参比波长为495、730 nm处测定南瓜中直链与支链淀粉含量;南瓜样品中直链淀粉占21.64%,支链淀粉占50.19%,总淀粉含量为71.83%,相对标准偏差分别为0.97%和1.06%,平均回收率分别为98.62%和99.42%,检出限分别为0.0116和0.0644 mg/mL。正丁醇结晶法能有效地分离南瓜直链与支链淀粉,双波长法可同时获得南瓜中3个淀粉含量指标,该方法既节省了样品,又提高了效率。同时,该方法的建立也为南瓜淀粉理化特性的研究提供了技术支持。     

小麦淀粉加工废液制备葡萄糖浆的糖化工艺优化

以降黏和液化后的小麦加工副产物为原料,将原料中的小麦淀粉制备为葡萄糖浆,并优化其糖化工艺以提高葡萄糖的回收率。探究葡萄糖淀粉酶添加量、普鲁兰酶添加量、糖化时间、糖化温度和糖化pH各单因素对糖化液还原糖含量(DE值)的影响。通过响应面实验得出最优工艺参数为葡萄糖淀粉酶添加量300 U/g、普鲁兰酶添加量0.17 U/g、糖化温度62 ℃、糖化pH3.9,糖化时间36 h,得到的DE值为69.45%。进一步通过高效液相-蒸发光散射检测法,测出淀粉转化率为78. 70%,葡萄糖总回收率为23.82%。说明从小麦加工废液中制取葡萄糖浆是切实可行的,对实际生产有着重要的指导意义。     

Effect of cold shock on the enhancement of β‐amylase activity during malting and malt processability for a red sorghum intended for brewing use

The low β‐amylase activity of sorghum malt is a major concern when malts are intended for use in brewing. Several studies have shown that the germination temperature plays an important role in β‐amylase synthesis. In this study, the cold shock treatment was envisioned as a means of improving β‐amylase synthesis during red sorghum malting. The results show that, when a high‐frequency decrease in the germination temperature is used, the obtained malt exhibits a significantly increased β‐amylase activity. This study shows that this increase is not sufficient to consider cold shock as a means of improving β‐amylase activity for red sorghum brewing use, as the processabilty of the malts is unsatisfactory. Copyright © 2015 The Institute of Brewing & Distilling     

Effect of bacterial amylase pretreatment on bioethanol production from starch-based solid waste (SBSW)

Fuels derived from biomass are essential in order to overcome the excessive dependence on petroleum. They also minimize the emissions of greenhouse gases. Pretreatment in biofuel production is a very important step. Pretreatment is not only costly in its own right but also has a pervasive impact on the cost of virtually all other processing operations. The present study investigates the effect of bacterial amylase pretreatment on ethanol production from different kinds of starch-based solid waste (SBSW). For this purpose four amylase-producing bacterial isolates were obtained from samples collected from municipal waste dumping sites. The isolated bacteria were then used for the pretreatment of SBSW for ethanol production. After bacterial amylase pretreatment, 13% yield of ethanol was obtained.