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1.
酶辅助法提取大青叶中总黄酮及抗氧化性研究 总被引：1，自引：0，他引：1
本论文采用酶辅助法提取大青叶中的总黄酮,先用纤维素酶酶解,再用乙醇回流提取大青叶中总黄酮。分别固定乙醇提取液的浓度为70%,料液比为1∶20g∕mL,回流时间为2h。初步探究了纤维素酶浓度、酶解pH、酶解温度、酶解时间四个单因素对大青叶中黄酮提取率的影响。设计正交实验确定酶辅助法提取大青叶中总黄酮的较佳条件为:纤维素酶浓度为4U/mL、酶解pH=4.5、酶解温度为40℃、酶解时间1.5h,总黄酮提取率高达2.85%。另外还研究了大青叶总黄酮提取液对羟自由基的清除活性,与BHT的抗氧化剂活性作对照实验,结果表明大青叶中的总黄酮对羟自由基有较强的清除活性。 相似文献
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Renata M. Collares Luiza V. S. Miklasevicius Mariana M. Bassaco Nina P. G. Salau Marcio A. Mazutti Dilson A. Bisognin Lisiane M. Terra 《Journal of Zhejiang University. Science. B》2012,13(7):579-586
This work evaluates the enzymatic hydrolysis of starch from cassava using pectinase, α-amylase, and amyloglucosidase. A central composite rotational design (CCRD) was carried out to evaluate the effects of amyloglucosidase, pectinase, reaction time, and solid to liquid ratio. All the experiments were carried out in a bioreactor with working volume of 2 L. Approximately 98% efficiency hydrolysis was obtained, resulting in a concentration of total reducing sugar released of 160 g/L. It was concluded that pectinase improved the hydrolysis of starch from cassava. Reaction time was found to be significant until 7 h of reaction. A solid to liquid ratio of 1.0 was considered suitable for hydrolysis of starch from cassava. Amyloglucosidase was a significant variable in the process: after its addition to the reaction media, a 30%–50% increase in the amount of total reducing sugar released was observed. At optimal conditions the maximum productivity obtained was 22.9 g/(L·h). 相似文献
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使用碱性蛋白酶处理,考察摇床转速、酶解时间和加酶量对纳米级珍珠粉得率的影响．试验结果表明：10g珍珠粉加入50mL去离子水,在摇床转速为180r／rain、酶解时间为8h、酶用量为0．5g时,纳米级珍珠粉得率为95．2％．凯式定氮实验表明：酶解前后珍珠粉蛋白质的含量分别为24．132％和22．010％,酶解后仅相对减少了0．088． 相似文献
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酶法水解植物蛋白 总被引：14，自引：0，他引：14
范恒君 《南宁职业技术学院学报》2000,5(3):57-61
以豆粕为原料 ,对蛋白酶水解植物蛋白的条件进行了研究。在酶解反应中 ,各因素对酶解作用的影响大小顺序是 :酶解时间 >p H值 >酶用量 >酶解温度。酶解反应的最适作用条件为 :温度 4 5℃、p H5.0和酶用量 30 0 0 u/ g。豆粕的水解度随时间的延长而增大 ,在4 5℃、p H5.0和 30 0 0 u/ g的条件下 ,水解豆粕 8h,水解产物的氮收率和水解度分别 55.4 6%和4 3.0 4 %。在同样条件下 ,水解油菜饼 ,水解产物氮收率和水解度分别为 57.59%和 4 4 .65%。 相似文献
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以菠萝蜜种仁淀粉为原料,采用β-淀粉酶（酶活为91500U／g）单酶法制备麦芽糖浆,在单因素实验的基础上,通过正交试验对工艺条件进行了优化,最佳工艺条件确定为：淀粉乳质量浓度20g／100mL、按质量分数加酶8％、pH5．5、（糖化）水解温度54℃、糖化时间8h。结果表明,在此条件下得到的产物淀粉转化率为41．6％,麦芽糖得率为47．5％。粗产品再经浓缩,得到的麦芽糖浆可溶性固形物含量（质量分数）为75％,色泽淡黄、体态均一透明、粘稠,具有麦芽糖香味,适合作为食品和食品辅料。 相似文献
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酶-超声提取地黄多糖及其抗氧化性研究 总被引：3，自引：0，他引：3
选用市售地黄为原料,利用纤维索酶解法结合热水浴提取法研究了提取温度、提取时间、提取液pH以及液料比对多糖提取量的影响．通过单因素试验得出地黄多糖提取工艺在液料比1：30的条件下的最佳参数为：提取温度40℃,提取时间25min,提取液pH为6．0,纤维素酶添加量为3．00％．在最佳参数组合下,多糖提取率为21．4％,地黄多糖对·OH的还原率为43．5％,此方法是简单、快捷和高效的提取方法． 相似文献
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采取酶解法辅助水蒸汽蒸馏法提取桔皮中精油,探索了纤维素酶用量、酶解处理时间、酶解温度、蒸馏时间等工艺条件对桔皮中精油提取率的影响。通过正交实验,酶解一水蒸汽蒸馏法提取桔皮中精油的最佳条件为：酶用量是2000U／g,酶解温度是55℃,酶解时间是140min,蒸馏时间是2h。采用此工艺条件,桔皮中精油的提取率是3．14％。 相似文献
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以冷冻杨梅鲜果为原料采用酶解浸提法制作杨梅酒,研究果胶酶和纤维素酶对杨梅酒出酒率的影响。通过单因素实验对影响杨梅酒出酒率的酶种类、酶解温度、酶解时间、酶底物比四因素进行考察,并通过正交实验法优化了杨梅酶解工艺参数。结果表明：确定果胶酶为酶解用酶,酶解法制备杨梅酒酶最佳工艺参数为酶解温度35℃、酶解时间4h,酶底物比2％。在此条件下,杨梅酒出酒率为（79．4±0．19）％,比同法不加果胶酶出酒率增加25．4％,并且过滤时间明显缩短。 相似文献
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Nutritional evaluation of caseins and whey proteins and their hydrolysates from Protamex 总被引：4，自引：0，他引：4
夏文水 《Journal of Zhejiang University. Science. B》2006,7(2):90-98
Whey protein concentrate （WPC 80） and sodium caseinate were hydrolyzed by Protamex to 5%, 10%, 15%, and 20% degree of hydrolysis （DH）. WPC 80, sodium caseinate and their hydrolysates were then analyzed, compared and evaluated for their nutritional qualities. Their chemical composition, protein solubility, amino acid composition, essential amino acid index （EAA index）, biological value （BV）, nutritional index （NI）, chemical score, enzymic protein efficiency ratio （E-PER） and in vitro protein digestibility （IVPD） were determined. The results indicated that the enzymatic hydrolysis of WPC 80 and sodium caseinate by Protamex improved the solubility and IVPD of their hydrolysates. WPC 80, sodium caseinate and their hydrolysates were high-quality proteins and had a surplus of essential amino acids compared with the FAO/WHO/UNU （1985） reference standard. The nutritive value of WPC 80 and its hydrolysates was superior to that of sodium caseinate and its hydrolysates as indicated by some nutritional parameters such as the amino acid composition, chemical score, EAA index and predicted BV. However, the E-PER was lower for the WPC hydrolysates as compared to unhydrolyzed WPC 80 but sodium caseinate and its hydrolysates did not differ significantly. The nutritional qualities of WPC 80, sodium caseinate and their hydrolysates were good and make them appropriate for food formulations or as nutritional supplements. 相似文献
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以花生壳为原料,以SO42-/TiO2-Al2O3固体酸为水解催化剂制备乙酰丙酸,探讨了固体酸用量,水解时间,水解温度,液固比对乙酰丙酸得率的影响。研究结果表明,当固体酸用量3.5%、水解时间150 min、水解温度250℃、液固比21:1(L/mg)时为较优的制备工艺。在该工艺条件下,乙酰丙酸得率为12.35%。 相似文献
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用脂肪酶在四氢呋喃中催化合成硬脂酸酯.研究了反应温度、时间、加水量、加酶量、不同的醇以及原料摩尔比对硬脂酸转化率的影响.最佳反应条件为:反应温度35℃,硬脂酸与乙醇的摩尔比为1∶1.3,加水量为0.4%,加酶量为600μg/g硬脂酸,反应时间24 h,硬脂酸转化率达72.4%. 相似文献
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Optically active form of α-cyano-3-phenoxybenzyl (CPB) alcohol, building block of pyrethroid insecticides, was synthesized as its acetate by the combination of anion-exchange resin (D301)-catalyzed transcyanation between m-phenoxybenzaldehyde (m-PBA) and acetone cyanohydrin (AC), and lipase (from Alcaligenes sp.)-catalyzed enantioselective transesterification of the resulting cyanohydrin with vinyl acetate. Through optimizing technological conditions, the catalyzing efficiency was improved considerably compared to methods previously reported. Concentrations of CPB acetate were determined by gas chromatograph. The enantio excess (e.e.) values of CPB acetate were measured by NMR (nuclear magnetic resonance) method. Effects of solvents and temperatures on this reaction were studied. Cyclohexane was shown to be the best solvent among the three tested solvents. 55 ℃ was the optimal temperature for higher degree of conversion. External diffusion limitation was excluded by raising the rotational speed to 220 r/min. However, internal diffusion could not be ignored, since the catalyst (lipase) was an immobilized enzyme and its particle dimension was not made small enough. The reaction rate was substantially accelerated when the reactant (m-PBA) concentration was as high as 249 mmol/L, but decreased when the initial concentration of m-PBA reached to 277 mmol/L. It was also found that the catalyzing capability of recovered lipase was high enough to use several batches. Study of the mole ratio of AC to m-PBA showed that 2:1 was the best choice. The strategy of adding base catalyst D301 was found to be an important factor in improving the degree of conversion of the reaction from 20% to 80%. The highest degree of conversion of the reaction has reached up to 80%. 相似文献
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INTRODUCTION Cyanohydrin compounds are useful syntheticintermediates in organic synthesis and are importantstarting materials for the synthesis of pharmaceuticals(Klibanov, 1990). Optically active cyanohydrin esterscan be obtained by enzymatic transesterification ofracemic cyanohydrins in organic solvent (Wang et al.,1989). (S)-α-cyano-3-phenoxybenzyl (CPB) alcoholis an important building block of pyrethroid insecti-cides and has received increasing interest for use inbiological agroche… 相似文献
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2，4-D在明胶／壳聚糖微球中的包埋与释放 总被引：3，自引：0，他引：3
以明胶／壳聚糖复合物为水相,液体石蜡为连续油相,农药2,4-二氯苯氧乙酸（2,4-D）为芯材,Span80为乳化剂,通过醛交联,采用反相乳液法制备了2,4-D-明胶／壳聚糖微球．考察了制备条件对微球形貌及包封率的影响,并研究了2,4-D在微球中的释放性能．结果表明：当Span80为1mL,油水比为4：1,用一定量甲醛与戊二醛的混合物为交联剂,芯壁材比大于1：14时,制备的微球形态圆整,表面光滑,分散性较好．该复合微球中2,4-D的包封率为70．8％,具有良好的缓释性能,作为一种新型农药剂型可望在农业领域得到应用． 相似文献
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对米渣浓缩蛋白进行复合蛋白酶和风味蛋白酶联合酶解试验,在单因素试验基础上通过正交试验优化酶解条件,所得水解液米渣蛋白提取率达到57.81%。对上述水解液进行了二次风味蛋白酶水解试验。米渣蛋白的提取率可以达到63.6%。将酶解产物冷冻干燥即得蛋白含量为84.62%的可溶性米渣蛋白粉。 相似文献
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本实验研究3种不同浓度(0.1、1.0、2.5 mg/L)的丁草胺对胡子鲶肝胰脏淀粉酶、脂肪酶活力的影响.结果表明,暴露2 d的高浓度组(2.5 mg/L)及暴露4 d的各浓度组淀粉酶活力显著提高,暴露6d的低浓度组(0.1 mg/L)及较高浓度组(1.0 mg/L)仍保持激活特性,而高浓度组(2.5 mg/L)淀粉酶活力则受到显著抑制;丁草胺暴露期间胡子鲶肝胰脏脂肪酶活力始终呈现显著的抑制作用,特别是高浓度组(2.5 mg/L)随着暴露时间的延长(6 d)则呈现极显著抑制. 相似文献
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Chen ML Guo Q Wang RZ Xu J Zhou CW Ruan H He GQ 《Journal of Zhejiang University. Science. B》2011,12(7):545-551
Surface display is effectively utilized to construct a whole-cell biocatalyst. Codon optimization has been proven to be effective
in maximizing production of heterologous proteins in yeast. Here, the cDNA sequence of Rhizopus oryzae lipase (ROL) was optimized and synthesized according to the codon bias of Saccharomyces cerevisiae, and based on the Saccharomyces cerevisiae cell surface display system with α-agglutinin as an anchor, recombinant yeast displaying fully codon-optimized ROL with high
activity was successfully constructed. Compared with the wild-type ROL-displaying yeast, the activity of the codon-optimized
ROL yeast whole-cell biocatalyst (25 U/g dried cells) was 12.8-fold higher in a hydrolysis reaction using p-nitrophenyl palmitate (pNPP) as the substrate. To our knowledge, this was the first attempt to combine the techniques of
yeast surface display and codon optimization for whole-cell biocatalyst construction. Consequently, the yeast whole-cell ROL
biocatalyst was constructed with high activity. The optimum pH and temperature for the yeast whole-cell ROL biocatalyst were
pH 7.0 and 40 °C. Furthermore, this whole-cell biocatalyst was applied to the hydrolysis of tributyrin and the resulted conversion
of butyric acid reached 96.91% after 144 h. 相似文献
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选用木瓜蛋白酶对低值巴浪鱼蛋白进行水解,分析各因素对鱼蛋白水解的影响,以水解度为特征性指标,通过L9(34)正交试验确定水解的最佳条件.实验结果表明:酶浓度为1 600 U/g,底物浓度3.5%,酶解时间5h,酶解温度60℃.在此条件下鱼蛋白的水解度为54.51%. 相似文献