原花青素高聚体水解工艺

为使原花青素资源得到充分利用,对抗氧化活性很低的高聚体水解工艺进行研究,以降低原花青素聚合度,提高抗氧化活性。以亚硫酸为水解介质,样品与亚硫酸体积比1:0.1,60℃恒温水浴反应10 min。结果显示,原花青素高聚体的平均聚合度由7.06降至4.02,自由基清除率由8.58%升高至43.59%。     

氨肽酶与中性蛋白酶协同水解大豆分离蛋白的研究

以大豆分离蛋白为底物,游离氨基酸含量、多肽分布、水解度为指标,氨肽酶ProteAXG为对照,开展中性蛋白酶和氨肽酶双酶协同水解的研究。在底物质量浓度6 g/dL,中性蛋白酶添加量5000 U/g,氨肽酶添加量9.75×105U/g,pH 8.5,温度50℃,水解4 h后,水解液中游离氨基酸含量13.6 mg/mL,多肽相对分子质量在1100以下,其中600左右的多肽约占16%,二肽三肽约占75%,水解度达50.8%。氨肽酶与中性蛋白酶优化后,水解度达62%。结果表明:该氨肽酶无论单独或与中性蛋白酶组合水解,都能达到较为深度的水解效果。     

甘蔗渣活性氧脱木素及其对纤维素酶解的影响

本文以温度、氧压、H2O2浓度和镁基氧化物的用量作为单因素实验条件,采用活性氧对甘蔗渣进行脱木素,然后进行纤维素酶解实验.探讨活性氧脱木素的效果及其对酶解效果的影响.结果表明,甘蔗渣经过活性氧脱木素后,木素脱除率高达96.23％,酶水解得率达到52.36％.甘蔗渣经过活性氧预处理后,大量木素脱除,有利于纤维素酶水解.     

木瓜蛋白酶水解海洋鱼鳞蛋白的工艺研究

研究了木瓜蛋白酶水解鱼鳞蛋白的单一影响因素,并采用L9(34)正交实验,考察了温度、时间、酶量、底物浓度等因素对水解鱼鳞蛋白的影响.确定了木瓜蛋白酶水解鱼鳞蛋白工艺条件,即温度65℃,时间75 min,酶量0.04 g/g鱼鳞,底物浓度10％,适合规模化生产.     

速生杨枝桠材P—RC APMP浆的酶促磨浆

研究了纤维素酶和木聚糖酶对速生杨枝桠材P—RCAPMP酶促磨浆性能的影响。实验结果表明酶预处理可以改善P—RCAPMP浆的磨浆性能和成浆质量。纤维素酶和木聚糖酶预处理纸浆打浆度提高3-11°SR,磨浆能耗明显降低。最佳酶用量为25IU／g。与未经过酶预处理速生杨枝桠材P—RCAPMP浆相比,纤维素酶预处理纸浆裂断长提高12％,撕裂指数提高13％,耐破指数提高14％,耐折度提高50％,白度提高1．2％ISO。木聚糖酶预处理纸浆裂断长略有提高,撕裂指数提高15％,耐破指数提高12％,耐折度提高75％,白度提高1．9％ISO。酶预处理可抑制纸浆返黄。纤维素酶的酶促磨浆效果好于木聚糖酶。     

热反应蟹昧香精的制备研究

以海蟹为原料,运用生物酶解技术,通过热反应(主要是美拉德反应)处理,研制风味逼真的蟹味香精.首先,对海蟹进行酶解,以水解度为指标,研究了碱性蛋白酶酶解海蟹的能力.通过单因素实验确定最佳酶解条件为:反应温度60℃,反应时间3h,加酶量0.5％,初始pH值8,料液比1 ∶ 1.其次,对热反应法制备蟹味香精的工艺进行了研究.通过对反应产物的感官评定,确定了制备虾味香精的基本反应原料,并运用正交实验的方法,确定了热反应的优化工艺条件,经优化得到最佳组合为:葡萄糖6 g,木糖2 g,甘氨酸1g,丙氨酸1.5g,谷氨酸0.5g,精氨酸0.5g,牛磺酸0.5g,硫胺素1g,酵母提取物10 g,蟹肉酶解液80 g,反应温度100℃,反应时间30 min,pH值6.     

Savinase和木瓜蛋白酶处理对羊毛性能的影响

为提高羊毛酶法防毡缩整理效果,分别进行了基于角质酶预处理的羊毛Savinase碱性蛋白酶和木瓜蛋白酶加工,考察了二步法协同处理对羊毛减量效果的影响.研究结果表明,相同酶浓度条件下,Savinase较木瓜蛋白酶具有稍高的酶解效率,试样失重率较高;相同失重率条件下,木瓜蛋白酶处理羊毛较Savinase处理样具有稍好的润湿性...     

响应面法优化黑曲霉HQ-1产纤维素酶固体发酵条件

采用单因素试验和响应面法对黑曲霉(Aspergillus niger) HQ-1产纤维素酶的固体发酵条件进行了优化并以滤纸酶活力作为响应值.首先通过单因素试验确定最适碳源为玉米秸秆粉/麦麸(1/1)及其最适含量为12.0g;最适氮源为(NH4)2SO4及其最适含量为1.5g.再利用Plackett-Burman设计筛选出影响滤纸酶活力的显著因素:含水量、培养温度和起始pH值.通过最陡爬坡试验逼近最大酶活力区域.最后用Box-Behnken设计及响应面分析确定产酶的最佳发酵条件为玉米秸秆粉6.0g、麦麸6.0g、(NH4) 2SO4 1.5g、KH2PO41.6g、MgSO4· 7H2O 0.8g、含水量73.5%、起始pH值为3.91、培养温度和培养时间分别为33.9℃和96h.经过优化,滤纸酶活力最高为59.432U/g,比未优化的酶活力最高值(13.511U/g)提高了3.40倍.     

Repeated hydrolysis process is effective for enrichment of omega 3 polyunsaturated fatty acids in salmon oil by Candida rugosa lipase

Enrichment of omega 3 polyunsaturated fatty acids (PUFA) in the glyceride fraction of salmon oil was performed by Candida rugosa lipase (CRL)-catalysed hydrolysis. Total omega 3 PUFA content in the product was 38.71% (mol.%), more than double of the initial level. The hydrolysis reaction was scaled up to 1 l in a stirred tank reactor without any decrease in the selectivity of the reaction. Moreover, non-steroselectivity and acyl chain specificity of CRL-catalysed hydrolysis, as well as CRL’s recognition of the whole triacylglycerol molecule, were proved. The product was purified by short path distillation, which was also shown to contribute to the recovery of omega 3 PUFA in residue. After the removal of free fatty acids, the final product was subjected to a second round of hydrolysis to concentrate omega 3 PUFA further to 50.58%. Recoveries of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) decreased slightly after the second round of hydrolysis, while oleic acid (OA) content was not affected.     

Impact of mild acid hydrolysis on structure and digestion properties of waxy maize starch

In this study, the molecular structure of acid-treated waxy maize starch residues was investigated, and the in vitro digestibility of the residues with 2.2 N HCl at 35 °C for different time periods, was assessed. The granular appearance of waxy maize starch was destroyed and small fractions formed aggregates. A change in chain-length distribution profiles occurred with the degradation of shortest A chains and long B chains in amylopectin. The rise in the ratio of absorbance height at 1047 cm⁻¹ to the height at 1022 cm⁻¹, the intensities of major peaks, X_c, T_p, T_c, and ΔH were observed during mild acid hydrolysis, but the X-ray diffraction patterns displayed A-type for all starches. The amount of rapidly digestible starch increased, whereas the amounts of slowly digestible and resistant starch decreased. These results demonstrate that the amorphous regions of starch granules, including the shortest A chains and long B chains, are preferentially hydrolysed and affect the slow digestion and resistance properties of waxy maize starch.