分步酶解猪骨粉提取猪骨素的工艺研究

本文以三氯乙酸可溶性氮(SN-TCA)的含量与水解度(DH)为测定指标,研究了中性蛋白酶、胰蛋白酶和木瓜蛋白酶复配后与风味蛋白酶分步酶解猪骨粉的工艺,优化了复合酶的最佳配比和酶解工艺参数。研究结果表明,第一步酶解三种酶的最佳配比为中性蛋白酶添加量5000 U/g、胰蛋白酶添加量4420 U/g和木瓜蛋白酶添加量3000 U/g,此时所得SN-TCA的最大含量为52.6%;复合酶最优的酶解工艺参数为酶解温度43.4℃、酶解时间6 h、pH 7.6、加酶量0.31%、料液比1:5.4,此时SN-TCA含量最高为55.42%;第一步酶解液灭酶后进行第二步酶解,保持体系料液比和pH不变,加入风味酶酶解温度为45℃、酶解时间为4 h、加酶量为0.4%,此时酶解效果最好,水解度可达到13.71%。     

蛋白酶酶解罗非鱼糜的工艺研究

用风味蛋白酶、复合蛋白酶和碱性蛋白酶对罗非鱼肉进行水解,以酶解液中氨基态氮含量为指标,选择出风味蛋白酶为水解罗非鱼蛋白的最适蛋白酶.单因素实验确定风味蛋白酶水解的最佳条件为:固液比为1:4、温度为50℃、未调节初始pH值(初始pH为6.9)、加酶量为0.6%(g/g,相对于鱼糜质量),酶解8h后酶解液中氨基态氮含量为1...     

风味酶水解乳清蛋白生产蛋白胨的工艺条件

为了提高原料乳清蛋白(Whey Protein Concentrate,WPC)的产品附加值,利用风味蛋白酶对WPC进行水解,生产蛋白胨产品。结果表明:最优工艺条件为E/S(18 000 U/100 mL),温度为55℃,pH值6.0,水解时间为4.0 h,底物质量分数为8%,水解度为46.4%。利用此工艺生产的蛋白胨产品在理化指标、氨基酸组成及质量分数上均要好于市售的同类产品。     

双酶法提取大豆多糖及其抗氧化性研究

本文以大豆粕为原料,采用双酶法提取大豆多糖,探讨了酶种类、双酶组合、酶解时间、pH、固液比等对提取率的影响,通过正交试验优化工艺条件,并对其抗氧化活性进行研究.结果表明,大豆多糖提取的最佳工艺条件为pH为6.0,酶解时间为6h,固液比1∶20,加酶量为酸性蛋白酶10％+风味酶8％,大豆多糖提取率为9.28％.大豆多糖对·OH、·O2-自由基表现出较强的清除能力,其IC5o分别为0.083mg/mL和0.078mg/mL.说明从大豆粕中提取的大豆多糖具有良好的抗氧化活性,可作为功能性食品基料添加到乳制品、饮料、面包、饼干等食品中,既增加了产品的保健功能,同时又提高了大豆粕的附加值,为大豆粕的综合开发利用提供技术支撑.     

响应面法优化豆豉蛋白酶解工艺

以豆豉蛋白为原料,选用木瓜蛋白酶与复合风味酶分步水解制备豆豉蛋白水解物。通过单因素试验和响应面分析,确定了木瓜蛋白酶的水解条件为:反应温度62.93℃、pH7.49、酶/底物4.91%、底物浓度5.48%,在此条件下水解5h;木瓜蛋白酶水解液再加入复合风味酶酶解,优化的水解条件为:在pH6.0,酶/底物为3%,55℃条件下反应3h,豆豉蛋白最终水解度达到28.37%。     

虾头自溶产物苦味与蛋白平均疏水度联系及脱苦

为了探明虾头自溶产物中苦味肽的分布以及蛋白疏水性与苦味的联系,采用超滤将虾头自溶产物分成不同组分,分别检测其苦味与平均疏水度,并研究自溶过程中添加复合风味蛋白酶协同水解虾头对苦味的改善作用。结果表明：虾头自溶产物的苦味主要来自分子质量为3～5kD 的肽;不同分子质量大小的自溶产物,平均疏水度越小苦味越大;添加复合风味蛋白酶协同水解虾头,与自溶比较,其蛋白回收率提高了3.5%,苦味降低了50%。     

Effect of Flavourzyme® on Angiotensin‐Converting Enzyme Inhibitory Peptides Formed in Skim Milk and Whey Protein Concentrate during Fermentation by Lactobacillus helveticus

Angiotensin‐converting enzyme inhibitory (ACE‐I) activity as affected by Lactobacillus helveticus strains (881315, 881188, 880474, and 880953), and supplementation with a proteolytic enzyme was studied. Reconstituted skim milk (12% RSM) or whey protein concentrate (4% WPC), with and without Flavourzyme^® (0.14% w/w), were fermented with 4 different L. helveticus strains at 37 °C for 0, 4, 8, and 12 h. Proteolytic and in vitro ACE‐I activities, and growth were significantly affected (P < 0.05) by strains, media, and with enzyme supplementation. RSM supported higher growth and produced higher proteolysis and ACE‐I compared to WPC without enzyme supplementation. The strains L. helveticus 881315 and 881188 were able to increase ACE‐I to >80% after 8 h of fermentation when combined with Flavourzyme^® in RSM compared to the same strains without enzyme supplementation. Supplementation of media by Flavourzyme^® was beneficial in increasing ACE‐I peptides in both media. The best media to release more ACE‐I peptides was RSM with enzyme supplementation. The L. helveticus 881315 outperformed all strains as indicated by highest proteolytic and ACE‐I activities.     

Enzymatic Hydrolysis of Recovered Protein from Frozen Small Croaker and Functional Properties of Its Hydrolysates

ABSTRACT:  Fish protein isolate were recovered from frozen small croaker using pH shift. The partial enzymatic hydrolysates were fractionated as soluble and insoluble parts. They were dried using the drum dryer and their functional properties were examined. The total nitrogen content of the enzymatic hydrolysates ranged from 12.9% to 13.7%. The degree of hydrolysis of precipitates was 18.2% and 12.2% for croaker hydrolysates treated with Protamex 1.5 MG ( Bacilllus  protease complex) and Flavourzyme 500 MG (endoproteases and exoproteases, Aspergillus oryzae ), respectively. The TCA supernatant, after centrifugation of hydrolysates, contained numerous peptides ranging from 100 to 4000 daltons. The solubility of the supernatants was higher than that of the precipitates at 0% to 3% NaCl and pH 2 to 10. The precipitate of Flavourzyme- and Protamex-treated hydrolysates showed a high emulsion activity index value compared to egg white and bovine plasma protein. In addition, the highest emulsion stability was observed for Protamex-treated precipitate hydrolysates. Emulsion stability of Protamex-treated precipitate hydrolysates was comparable to those of protein additives (egg white, bovine plasma protein, and soy protein concentrate). Water and fat binding capacity of precipitates were higher than those of supernatant. The results indicate that precipitate hydrolysate from undersized croaker can be used in processed muscle foods as a functional and nutritional ingredient.     

Investigation of the peptides with calcium chelating capacity in hydrolysate derived from spent hen meat

Calcium peptide chelates are developed as efficient supplements for preventing calcium deficiency. Spent hen meat (SHM) contains a high percentage of proteins but is generally wasted due to the disadvantages such as hard texture. We chose the underutilized SHM to produce peptides to bind calcium by proteolysis and aimed to investigate chelation between calcium and peptides in hydrolysate for a sustainable purpose. The optimized proteolysis conditions calculated from the result of response surface methodology for two-step hydrolysis were 0.30% (w_enzyme/w_meat) for papain with a hydrolysis time of 3.5 h and 0.18% (w_enzyme/w_meat) for flavourzyme with a hydrolysis time of 2.8 h. The enzymatic hydrolysate (EH) showed a binding capacity of 63.8 ± 1.8 mg calcium/g protein. Ethanol separation for EH improved the capacity up to a higher value of 68.6 ± 0.6 mg calcium/g protein with a high association constant of 420 M⁻¹ (25°C) indicating high stability. The separated fraction with a higher amount of Glu, Asp, Lys, and Arg had higher calcium-binding capacity, which was related to the number of ─COOH and ─NH₂ groups in peptide side chains according to the result from amino acid analysis and Fourier transform infrared spectroscopy. Two-step enzymatic hydrolysis and ethanol separation were an efficient combination to produce peptide mixtures derived from SHM with high calcium-binding capacity. The high percentage of hydrophilic amino acids in the separated fraction was concluded to increase calcium-binding capacity. This work provides foundations for increasing spent hen utilization and developing calcium peptide chelates based on underutilized meat.     

复合酶法水解蟹肉的研究

研究碱性蛋白酶和复合风味蛋白酶水解螃蟹肉的工艺条件。探讨了时间、酶用量、初始pH值、固液比浓度和温度对螃蟹肉水解效果的影响。在单因素试验的基础上,通过多因素响应面设计实验,获得最适水解工艺条件为时间4h、碱性蛋白酶先水解1h后再加入复合风味蛋白酶共同作用、初始pH值为8.3,固液比浓度为1∶2.5,温度60℃,碱性蛋白酶用量为1.2×10-3AU/g(蛋白质)、复合风味蛋白酶用量1.5LAPU/g,此时蛋白质的水解率为22.8%,TCA可溶性氮增长率含量为40.47%。