The effect of germination and kilning on the cyanogenic potential,amylase and alcohol levels of sorghum malts used for burukutu production

Grain sorghum of the red and white varieties was malted by steeping in water for 18 h, germinated over 5 days and kilned at 50 °C. The malts were analysed for amylase activities and cyanogenic potential and used to produce burukutu, an alcoholic beverage. The alcohol content of the burukutu was recovered by distillation and determined by the refractive index method. α‐Amylase activity peaked on malting day 3 and was higher in the white malts. β‐Amylase activity peaked on day 3 in the red malts and on day 4 in the white malts, but was higher in the red malts. Dhurrinase activity was highest on malting day 4, with a higher activity in the red malts. Kilning at 50 °C reduced the activities of these enzymes. The dhurrin content increased during germination and was consistently higher in the white malts, in which there was evidence of dhurrin mobilisation. In the red malts the dhurrin content increased during germination but decreased progressively after kilning; evidence of dhurrin mobilisation was apparent as from malting day 4. Burukutu produced from the red malts gave higher alcohol contents than that from the white malts. Maximum alcohol yields were obtained on malting day 3 in the red malts and on day 5 in the white malts. © 2000 Society of Chemical Industry     

Purification of α‐amylase from human saliva by superparamagnetic particles

BACKGROUND: Several studies of magnetic carrier technology have focused on the application of separation technology, because the magnetic support can separate the target from the reaction medium by application of a magnetic field and because the magnetic carrier can be easily recovered. In the present study, superparamagnetic iron oxide (SPIO) modified by epichlorohydrin was employed as a support whose surface could be coated with starch. The starch‐coated support was used for isolating human salivary amylases. RESULTS: The results showed that the starch‐SPIO support could isolate amylases from human saliva with 91.1% recovery and 3.5‐fold purification to high specific activity. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the purifed amylase comprised two isoamylases with estimated molecular weights of 55 and 59 kDa. The activities of crude and purified amylases showed optimal pH values of 6–7 and 7 and optimal temperatures of 40 and 30 °C respectively. The thermal stability range for both crude and purified amylases was between 20 and 40 °C. CONCLUSION: The attachment of substrates to SPIO could offer a novel and efficient method for purifying enzymes either as an initial step prior to further purification or as a final step for diagnostic usage. Copyright © 2009 Society of Chemical Industry     

黑米发芽过程中淀粉酶活力及淀粉含量变化

以黑米为原料,采用不同条件对黑米进行发芽处理,考察发芽过程中发生的生物化学变化,研究淀粉酶活力及其淀粉含量在发芽过程中的变化规律。试验证明,黑米发芽过程中的淀粉酶活力发生较大变化,呈上升趋势。淀粉含量呈下降趋势。采用Ca2+进行前处理比用去离子水进行前处理变化趋势更为显著。     

Analysis of cyclodextrins using a calorimetric biosensor

A thermostable α-amylase catalyzed the exothermal hydrolysis of cyclodextrins. It was immobilized covalently via a spacer on controlled pore glass (CPG-10) or Silicagel. The temperature signal caused by the reaction heat of the cyclodextrin hydrolysis was determined in a one column calorimetric system (enzyme thermistor). It was correlated to the cyclodextrin concentration and depended on the type of enzyme carrier and kind of cyclodextrin hydrolyzed. The proposed technique offers a direct route to the determination of α-amylase activity, and the results are of importance for analysis of cyclodextrin concentration.     

淀粉酶废液在酒精生产中的应用研究

将中温α-淀粉酶和糖化酶的发酵废液添加到利用木薯粉生产酒精中,通过实验研究酶废液的添加对酒精产量以及对发酵过程中酿酒酵母的影响.实验证明,添加酶废液可以提高0.6％的酒精产量;在酒精发酵过程中,对酵母生长的负作用不明显.     

添加淀粉酶改进低发芽率麦芽酿酒质量

以低发芽率麦芽为原料，通过添加淀粉酶，采用一次煮出糖化法生产啤酒．糊化锅温度为７０℃，添加α－淀粉酶１．０‰，糖化锅温度为６３℃，添加β－淀粉酶４．０‰，生产出的啤酒符合ＧＢ４９２７－９１（一级）质量标准．     

超声波对淀粉酶退浆工艺影响机理的探讨

借助超声波预处理和未经超声波预处理淀粉酶活力测定结果的比较,以及在超声波条件下和常规条件下淀粉酶活力测定结果的比较,对超声波促进淀粉酶退浆工艺的可能机理进行了探讨,分析了超声波条件下影响淀粉酶活力的因素。     

液体洗涤剂中复合酶稳定性的研究

研究了由碱性蛋白酶、淀粉酶通过微胶囊复配而成的复合酶在不同温度和pH下的特性，以及含水量、保护剂和表面活性剂对酶活力稳定性的影响。结果表明，该复合酶的最适反应温度为50℃，最适pH为9．0，在温度20～50℃，pH6～10，水的体积分数小于40％及各表面活性剂的洗涤浓度范围内均有良好的稳定性。     

THE EFFECTS OF MASHING TEMPERATURE AND MASH THICKNESS ON WORT CARBOHYDRATE COMPOSITION

Temperature and mash thickness are shown to affect both mash performance and enzyme activity. Alpha amylase was found to be considerably more resistant to heat inactivation than was beta amylase. This difference was reflected by changes in wort fermentability that were manifest at temperatures below those which affected levels of extract. Increasing the mashing temperature from 65°C to 80°C had only a slight effect on extract but reduced wort fermentability from over 70% to less than 30%. At 85°C and over, when temperature had a significant effect on alpha amylase, as well as on beta-amylase, extract was lost and starch was present in the wort. Diluting the mash with liquor had a similar effect to that of increasing temperature on both the amylolytic enzymes and on the mash performance. Thin mashes contained more starch and fewer fermentable sugars than did thick mashes at the same temperature. These changes can be related to the stability of the amylolytic enzymes.     

Sweetpotato α- and β-Amylases: Characterization and Kinetic Studies with Endogenous Inhibitors

Sweetpotato α- and β-amylases were characterized to assist optimization of direct hydrolysis of starch by endogenous amylases. In kinetic studies purified starch was substrate, and ascorbate, oxalate, phenolics, phytate and sweetpotato extracts were assayed for inhibitory activity. α-Amylase had optimum pH between 5.8 and 6.4 and was stable from pH 5.0 to 9.0. Optimum activity occurred at 71.5°, but it was inactivated by heat in the absence of Ca²⁺ at > 63°. The Km for soluble starch was 2.08 mg/mL. The molecular weight was 45000 daltons. α-Amylase activity was reduced up to 70% by 0.2 mM K-ascorbate and moderately by Na-oxalate and Na-phytate. β-Amylase had optimum pH between 5.3 and 5.8, and was stable from pH 4.0 to 8.0. Its maximum activity was at 53° and it was inactivated at 60°. Km for soluble starch was 3.71 mg/mL. At 0.08 mM, K-ascorbate strongly inhibited β-amylase activity.