内源性蛋白酶酶解南美白对虾虾头、虾壳的研究

研究了温度、固液比、时间、pH值等因素对南美白对虾虾头内源性蛋白酶酶解反应的影响,并以4因素3水平正交试验确定了反应的最佳条件。结果表明,以氨基酸态氮与水解度为指标,最佳水解条件为:固液比1:3.5、温度55℃、时间4h、pH8,氨基酸态氮含量6.53mg/g虾头;短肽最佳组合:固液比1:3.5、温度45℃、时间3h、pH6。     

牡蛎酶解过程的成分变化及脱腥初步研究

对牡蛎原浆液、酶解液及其浓缩液的基本营养成分进行分析比较,分别采用了活性炭吸附、β-环状糊精包埋法和酵母发酵法对牡蛎酶解液进行脱腥,研究了温度,时间,pH和脱腥剂用量等对脱腥效果的影响. 结果表明:牡蛎蛋白质、水分含量分别为9. 46%和81. 42%:酶解后,蛋白质和水分含量分别为7. 36%和83. 18%;酶解液浓缩后,蛋白质含量高达52. 55%. 活性炭脱腥效果最优:用量为0. 5%,在pH7. 0、30℃条件下吸附0. 5 h,酶解液基本无腥味,蛋白质回收率可达84. 65%. 促进牡蛎酶解液的推广应用.     

宇佐美曲霉L-336酸性蛋白酶2m~3罐中试发酵研究报告

宇佐美曲霉栗色变种Ｌ－３３６是分泌高单位酸性蛋白酶的生产菌，在摇瓶小试工艺基础上进行２ｍ３罐发酵中试，结果表明：较优发酵培养基（％）为黄豆粉４．３，玉米粉１．０，鱼粉０．７，蚕蛹水解液１０，Ｎａ２ＨＰＯ４０．２，ＣａＣｌ２０．５，ＮＨ４Ｃｌ１．０，豆油１．６；风量为０～２５ｈ时１∶０．４ｖ／ｖ／ｍ，２５～５０ｈ时１∶１．０ｖ／ｖ／ｍ，５０ｈ后１∶１．３ｖ／ｖ／ｍ；接种量１０％，温度３１℃，搅拌转速２００ｒ／ｍｉｎ，发酵周期７５ｈ。在上述条件下，发酵酶活力稳定在５５００ｕ／ｍｌ左右。     

Effect of the fungal protease EPg222 on proteolysis and texture in the dry fermented sausage ‘salchichón’

Proteolytic activity of the fungal protease EPg222 and its effect on the texture of the dry fermented sausage ‘salchichón’, which has a long ripening process, was assayed. Samples with enzyme added showed a significant reduction of myofibrillar protein concentration during the ripening period, compared with a control, and proteolytic activity of the enzyme led to a higher accumulation of non‐protein and ‐amino acid nitrogen. Analysis of volatile compounds in ripened dry fermented sausages revealed that only in EPg222 batches were branched compounds derived from amino acids catabolism detected that are associated with the flavour of dry cured meat products. The texture profile analysis showed reduction in hardness, gumminess and chewiness values in treated compared with control sausages. The effect of this enzyme could be of great interest in stimulating proteolysis, in flavour development and in reducing the hardness of dry fermented sausages produced by a long ripening process. Copyright © 2004 Society of Chemical Industry     

B.subtilis蛋白酶高产菌株的筛选与鉴定

本文以中性蛋白酶生产菌Ｂ．ｓｕｂｔｉｌｉｓＡＳ１．３９８为出发菌，用ＮＴＧ与紫外辐照相结合的方法对其进行复合诱变，筛选到一株蛋白酶活性明显高于出发菌的正突变株，命名为Ｂ．ｓｕｂｔｉｌｉｓＭＬ。通过对该突变株蛋白酶活性曲线的绘制、酶作用最适ＰＨ的确定、所产一的酶性质的分析及比酶活性的测定，发现该突变株扩酶活性比ＡＳ１．３９８至少高出３０％，最适反应ＰＨ７－８，酶活性受ＥＤＴＡ的强烈抑制，其突变位点很     

酶法制备花生粕醒酒多肽

为更合理有效地利用花生粕资源,制备具有醒酒作用的花生粕多肽,本实验以Alcalase AF 2.4L蛋白酶酶法制备花生粕醒酒肽,经分级分离后,通过体外和动物实验验证其醒酒效果。结果表明,花生粕醒酒肽制备最佳工艺条件为：酶解时间3 h、酶解温度35 ℃、pH 9.5及料液比1∶30（m/V）。该条件下乙醇脱氢酶（alcoholdehydrogenase,ADH）激活率及多肽得率均较高。经分级分离后,分子质量在1 000～3 000 D的多肽对ADH激活作用最强,激活率为30.47%。G25凝胶色谱分析表明,花生粕多肽中小于3 000 D的多肽占89.55%,ADH激活率为29.25%。动物实验证明,花生粕多肽对小鼠有显著的防醉醒酒作用。小鼠血液乙醇含量测定结果表明,高剂量的花生粕多肽在60～90 min内能显著降低小鼠血液中的乙醇含量。     

大豆蛋白酶解肽的分子量分布及抑制ACE活性关系研究

研究不同蛋白酶作用的酶解肽表现在血管紧张素转化酶(ACE)活性抑制差异,酶解产物的水解度、分子量分布与ACE抑制率的相互关系。用胰蛋白酶、胃蛋白酶、中性蛋白酶、木瓜蛋白酶、碱性蛋白酶等五种蛋白酶对大豆分离蛋白酶解,进行了多肽增量、水解度、超滤膜分离及其ACE抑制率对比等实验。结果表明,碱性蛋白酶的多肽增量最大,胃蛋白酶次之,依次为木瓜蛋白酶和中性蛋白酶,胰蛋白酶则出现反常;水解度随着酶解的时间而增加,碱性蛋白酶的最大水解度可达到21%,依次为胃蛋白酶、木瓜蛋白酶和中性蛋白酶,最低为胰蛋白酶仅为9%左右;与此对应的碱性蛋白酶的酶解物的ACE活性抑制率为最高(44.9%),胃蛋白酶次之(43.5%)。分子量范围在1000Da以下组分对ACE的抑制效果最高,碱性蛋白酶作用获得的小分子肽组成为71.25%,胃蛋白酶的为69.35%,但其对应的ACE抑制率却为64.57%和78.49%。中性蛋白酶、木瓜蛋白酶和胰蛋白酶作用获得的小分子肽的ACE抑制率分别为45.7%、47.3%和29.6%。胃蛋白酶的降压肽制备效果为最好,其次为碱性蛋白酶、木瓜蛋白酶、中性蛋白酶和胰蛋白酶。     

嗜碱性芽孢杆菌产高碱碱性蛋白酶发酵培养基及发酵条件的研究

对一株高产高碱碱性蛋白酶的嗜碱性芽孢杆菌的发酵培养基及发酵工艺进行了优化。确定了发酵培养基所采用的棉籽饼粉最适粒度为 80目 ,麦芽糊精的最佳DE值为 3 0 %。并确定了该菌株的最适发酵培养基配方为 ( g/1 0 0mL) :棉籽饼粉 3 ,酵母浸粉 1 75 ,麦芽糊精 1 0 ,柠檬酸钠 0 3 ,CaCl2 0 3。K2 HPO4 1 ;最适摇瓶发酵条件为 :种龄 1 2h ,接种量 2 %,装液量 5 0mL/2 5 0mL ,摇床转速 2 0 0r/min ,3 4℃ ,发酵 5 4h ,碱性蛋白酶的发酵单位可达 3 3 985u/mL ,比优化前提高了5 4 48%。此外 ,还进行了 5L罐放大实验 ,在 5L罐所确定的最适工艺条件下 ,发酵单位可达3 65 79u/mL。     

Release of short and proline-rich antihypertensive peptides from casein hydrolysate with an Aspergillus oryzae protease

Angiotensin-I converting enzyme inhibitory activities were measured after hydrolysis of casein by 9 different commercially available proteolytic enzymes. Among these enzymes, a protease isolated from Aspergillus oryzae showed the highest angiotensin-I converting enzyme inhibitory activity per peptide. The A. oryzae peptide also showed the highest antihypertensive effect in spontaneously hypertensive rats when the systolic blood pressure was measured 5 h after oral administration of 32 mg/kg of various enzymatic hydrolysates. Significant antihypertensive effects were observed with dosages of 9.6, 32, and 96 mg of the A. oryzae peptide/kg of body weight (BW), and the effects were dependent on these peptide dosages.Analysis of peptide length showed the A. oryzae hydrolysate was the shortest of all tested casein hydrolysates; the peptide mixture had an average value of 1.4 amino acids (AA) in the sequence. To further characterize the A. oryzae hydrolysate, we analyzed the AA sequence of the whole peptide mixture. Various AA were detected at the first AA position, however, an increased number of Pro residues were observed at the second and third position of the A. oryzae hydrolysate. No strong signals were detected after the fourth AA position of the A. oryzae hydrolysate. These results suggest that the casein hydrolysate of A. oryzae, which expressed potent antihypertensive effects in spontaneously hypertensive rats, mainly contain short peptides of X-Pro and X-Pro-Pro sequences.     

新疆传统乳制品中产蛋白酶乳酸菌的筛选及产酶条件优化

以新疆传统发酵乳制品为分离源,分离筛选产蛋白酶的乳酸菌,并通过形态学观察及16S rDNA序列比对鉴定菌株。以碳源、氮源、金属盐、磷酸盐的种类和添加量为影响因素,以蛋白酶活作为评价指标,通过单因素试验和正交试验优化乳酸菌产蛋白酶的产酶条件。结果表明,从样品中分离筛选出乳酸菌16株,产蛋白酶的乳酸菌4株（编号为A1～A4）,分别被鉴定为戊糖片球菌（Peciococcus pentosaceus）、发酵乳杆菌（Lactobacillus fermentum）、短乳杆菌（Lactobacillxus brevis）、乳酸明串珠菌（Leuconostoc lactis）。在以4.0%葡萄糖为碳源、4.0%牛肉膏为氮源、0.02%的镁离子为金属盐、0.7%的K2HPO4为磷酸盐的条件下,菌株A2产蛋白酶活最高为65.92 U/mL。