扇贝边酶解技术研究

研究了混合酶水解扇贝边蛋白质的技术条件，并和单酶水解情况进行了比较。结果表明，混合酶水解可提高水解液中氨基酸态氮（AAN）含量，同时改善了水解液风味。本文引进二次正交旋转组合试验设计方案，系统地研究了影响混合酶水解效果的相关因素，得出了扇贝边水解液中氨基酸态氮生成量的变化规律一回归模型。应用该模型可对水解液中AAN生成量进行预测，也可进一步优化选择扇贝边的酶解条件。     

酶水解美洲帘蛤蛋白质及产物抗氧化活性初探

采用二苯基苦基苯肼(DPPH)自由基法和改进的邻苯三酚法检测了胃蛋白酶对美洲帘蛤的水解作用及其水解液的抗氧化活性,探讨了酶质量分数、底物质量分数、pH、水解时间、温度对美洲帘蛤蛋白质水解度的影响.试验结果表明,酶质量分数为5%,底物质量分数为10%.pH 1.0,酶解3 h.温度为50℃时可以获得较高的水解度,同时水解液对超氧阴离子自由基和DPPH自由基有较高的清除率.     

蛋白酶对文蛤肉水解效果的研究

本文探讨了木瓜蛋白酶、胰蛋白酶、精制中性蛋白酶、酸性蛋白酶、复合蛋白酶和风味蛋白酶等6种蛋白酶对文蛤肉的水解效果,以文蛤肉水解液的水解度、氮收率及水解得率为指标,并对酶解液进行感官鉴评和风味评分,结果表明精制中性蛋白酶、胰蛋白酶和风味蛋白酶为适用于文蛤肉水解的蛋白酶。     

胰蛋白酶水解虾头壳制备钙结合肽的工艺条件优化研究

在单因素试验研究时间、底物浓度、pH,酶浓度和温度对蛋白水解度和酶解液中可溶性钙含量的影响基础上,通过响应面分析法对酶解条件进行了优化,得出最佳酶水解工艺条件为:底物浓度10%,pH 7.4,温度50℃,酶添加量1.39%,水解5h.在此条件下,酶解液水解度为29.0%,可溶性钙含量为176.4 mg/ml,水解液经凝...     

牡蛎的营养成分及蛋白质的酶法水解

研究了牡蛎肉的营养成分和其蛋白质的酶法水解。结果表明,牡蛎肉中蛋白质和糖原含量分别为50.63%和22.41%,其氨基酸组成完善,8种必需氨基酸占氨基酸总量的40%;537酸性蛋白酶比较适合于牡蛎蛋白质的水解,其优化的作用条件为:加酶量为1700U·g-1蛋白质、pH4、50℃、2h,在此条件下,水解液中的蛋白质和糖原提取率分别为78.23%和50.58%,水解液中的游离氨基酸和牛磺酸分别占总氨基酸的39.27%和12.47%。     

不同酶解条件对Ti鱼蛋白水解物苦味及氨基酸组成的影响

研究了不同酶解的Ti鱼可溶性产物苦味及呈味氨基酸组成的差异，以及其水解时间、水解率对苦味的影响。结果表明，随着酶解时间延长和水解率的提高，几种水解液的苦味值都有不同程度增强。胃蛋白酶和胰蛋白酶的复合水解液表现出随水解时间的延长，水解率提高明显，苦味强度上升平缓。当水解率从42％提高到78％时，苦味值只提高了2，水解液总的苦味分值为3．5；枯草杆菌蛋白酶水解2h后苦味分值急剧提高，水解4h后苦味分值达到6，水解液味道很苦，水解率从32％提高到62％时，苦味分值提高到了7，水解液总的苦味值为8．5。两种方法水解获得的可溶性产物氨基酸及必需氨基酸组成含量接近，但胃蛋白酶、胰蛋白酶复合水解的可溶性产物具有更高的氨基酸分值，主要鲜味氨基酸含量略高于枯草杆菌蛋白酶水解产物，苦味氨基酸则相反。     

缢蛏肉的蛋白酶水解工艺研究

实验研究了用枯草杆菌中性蛋白酶水解缢蛏肉的工艺条件,通过单因素试验和正交实验,得出了最适水解工艺条件为加酶量2.4％,水解温度50℃.料水比1:3。pH值为中性,时间为6h.水解产物的水解率和总的氮收率分别为42.46％和83.04％。水解液经脱腥等处理后可用于复合调味料和营养口服液的生产。     

酶法水解加工废弃鱼头的工艺探索

鱼头营养丰富 ,富含蛋白质、脂肪、氨基酸等物质。利用酶对加工中废弃鱼头进行水解 ,制得香味浓郁、红褐色的水解液 ,其中氨态氮含量为 6 4mg/mL。     

酶法提取鱿鱼皮胶原蛋白工艺条件的研究

研究了酶法提取鱿鱼皮胶原蛋白的工艺条件。根据5种蛋白酶水解液中羟脯氨酸（HYP）的含量,确定了胰蛋白酶和木瓜蛋白酶这2种提取率高的酶为水解用酶,采用L16（4^5）正交试验确定了这2种酶水解鱿鱼皮以制备胶原蛋白的最佳酶解条件。结果表明,胰蛋白酶和木瓜蛋白酶水解鱿鱼皮以制备胶原蛋白的最佳温度、加酶量、底物浓度、pH、时间分别为55℃、1200U·g^-1、1：20、pH8.0、4h和50℃、3200U·g^-1、1：20、pH6.0、6h。2种蛋白酶提取的胶原蛋白含量分别为11.08%和11.36%,提取率分别为95.16%和97.56%。     

鱼鳞制胶及其综合利用

鱼鳞很适合提取优质胶。通过酸碱水解和酶促水解的比较，得出酶解工艺更适合鱼鳞制胶，并确定了酶解的最佳条件。鱼鳞胶的应用非常广泛，其副产品也可以利用。     

Effect of Degree of Hydrolysis and Protease Type on the Antioxidant Activity of Protein Hydrolysates From Cuttlefish (Sepia officinalis) By-Products

We have investigated the antioxidant activities of eight hydrolysates from cuttlefish by-products obtained by treatment with various gastrointestinal proteases (chymotrypsin, trypsin, and crude alkaline enzyme extracts from cuttlefish and sardinelle) and bacterial proteases (Alcalase and crude enzymes from Bacillus pumilus A1, Bacillus mojavensis A21, and Bacillus cereus BG1). The antioxidant activities of the cuttlefish by-products protein hydrolysates (CPHs) were evaluated using various in vitro antioxidant assays, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, reducing power, and total antioxidant capacity. All hydrolysates showed different degrees of hydrolysis (DH) and varying degrees of antioxidant activity. Among the different hydrolysates, cuttlefish crude enzyme hydrolysate exhibited the highest antioxidant activity, followed by sardinelle crude enzyme and Alcalase hydrolysates. Further, CPHs with different degrees of hydrolysis were prepared by treatment with proteolytic enzymes from cuttlefish, sardinelle, and B. mojavensis A21. All hydrolysates showed a greater antioxidative activity as indicated by all the methods considered. In addition, antioxidant activity in hydrolysates was positively correlated with the increase of DH. The results of this study indicated that CPHs might be a good candidate for further investigation in developing new antioxidants.     

鲣鳔蛋白抗氧化酶解物制备工艺

为有效提高鲣鳔蛋白的附加值,研究以DPPH自由基清除率为抗氧化活性评价指标,采用蛋白酶酶解制备活性多肽的工艺,选用菠萝蛋白酶、复合蛋白酶、碱性蛋白酶、木瓜蛋白酶、胃蛋白酶、胰蛋白酶、中性蛋白酶7种酶在各自最适的条件下酶解,筛选出复合蛋白酶为最适用酶,通过单因素实验分别研究加酶量、溶液初始p H、酶解温度和时间对酶解物抗氧化活性的影响,在此基础上,根据响应面法优化鲣鳔抗氧化酶解物的制备工艺。结果显示,最佳酶解工艺条件为加酶量8.53 U/mg,p H 5.54,温度50.03°C,时间5.07 h。此外,利用超滤法对最佳条件下制备的酶解物进行初步分级,得到分子质量分别为大于10 000 u、3000~10 000 u和小于3000 u的3段组分,且这3段组分对DPPH自由基的半抑制浓度IC50值分别为0.64、0.52和0.37 mg/m L。研究表明,最优条件下制备的酶解物的DPPH清除率达72.00%,与模型预测值71.60%接近,且其中小于3000 u的组分具有较强的DPPH自由基清除活性。     

Antioxidant Efficacy of Protein Hydrolysates from Large Yellow Croaker (Pseudosciaena crocea) in D-galactose-Induced Aging Mice

The antioxidant efficacy of protein hydrolysates prepared from large yellow croaker (Pseudosciaena crocea) by enzymatic hydrolysis using neutral protease was evaluated in D-galactose-induced aging mice. Animals were divided into normal and model control groups, and low-, middle-, and high-dose groups (50, 100, and 300 mg/kg; LYCHs), as well as tocopherol (VE) and antagonistic (LYCHs + VE) groups. The study was carried out for 30 days. Administration of D-galactose induced oxidative damage with a significant rise (p < 0.01) in malondialdehyde and a reduction in several endogenous antioxidant enzymes and glutathione (GSH). Treatment with large yellow croaker protein hydrolysates stimulated an increase in superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities, increased levels of reduced glutathione, and decreased malondialdehyde, compared with the model control group. Additionally, hepatocellular damage was evaluated by measuring aspartate aminotransferase and alanine aminotransferase levels. These results demonstrate the protective role of large yellow croaker protein hydrolysates in D-galactose-induced oxidative stress, as well as their potential as nutraceuticals or adjuvant agents for disease prevention.     

The Feasibility of Increasing Lipid Extraction in Tilapia (Oreochromis niloticus) Waste by Proteolysis

ABSTRACT

The aim of the present study was to evaluate the feasibility of increasing lipid extraction in tilapia (Oreochromis niloticus) waste using different enzymes and to minimize the periods of hydrolysis to evaluate the performance of the lipid fractions. When processing waste tilapia, commercial enzymes were added that were composed of neutrase and alcalase acting at different hydrolysis times to produce the best yields. The treatment proved feasible for obtaining the protein hydrolysates. The type of enzyme and the hydrolysis time determined the degree of fractionation. The enzymes performed well, and the highest efficiency occurred within 2 h of hydrolysis. By fractionating, the obtained by-products can be applied in the preparation of feed, as the lipid fraction treatments yielded significant amounts of polyunsaturated fats and suitable n-6/n-3 ratios.     

Dietary Protein Hydrolysates from Animal By-Products: Digestibility and Enzymatic Activity for Dourado Salminus brasiliensis

Fishmeal (FM) is a high-cost and scarce feedstuff. Notwithstanding, the formulation and processing of diets for carnivorous fish strongly rely on FM as a protein source, given its palatability and biological value. Animal by-product hydrolysates are high-quality feedstuff and can substitute FM in aquafeeds. This study evaluated the digestibility of hydrolysates from tilapia residue (TR), tuna head (TH), swine liver (SL), and poultry liver (PL), and the profile of digestive enzymes in juvenile dourado, Salminus brasiliensis, a carnivorous Characin, fed diets containing graded levels of the hydrolysates. Inclusion of hydrolysates in diet formulations lowered the pH of feed but did not alter feed intake by fish. Higher apparent digestibility coefficients (ADCs) of diets were recorded for fish fed diets containing TR and SL, and lower ADCs were recorded for fish fed diets containing TH. Protease and lipase activities in the animal’s stomach were higher, especially for those fed with diets containing SL. Amylase activity was higher in pyloric caeca, whereas in the intestines, the higher activity was seen in fish fed control and TR diets. Animal by-product hydrolysates were highly digestible for dourado, and the enzymatic profile of fish was influenced by the nutrient contents of diets.     

Antioxidative Properties of Squid Protein Hydrolysates Prepared Using Seer Fish Visceral Enzymes in Comparison with Commercial Enzymes

ABSTRACT

In the present study, antioxidative potential of squid protein hydrolysates (SPH) prepared using endogenous pepsin and trypsin prepared from the stomach and pyloric ceca of seer fish respectively was evaluated, in comparison with commercial enzymes. Degree of hydrolysis (DH) of the pepsin SPH ranged between 8–11% and trypsin SPH between 12–14% after 150 min of hydrolysis. SPH prepared with endogenous enzymes had significantly higher DH than commercial enzymes. Pepsinogen SPH expressed more DH than pepsin SPH. Trypsin SPH exhibited good metal chelating ability (98%), which was equivalent to EDTA at 130 ppm. Pepsin SPH showed higher super oxide anion scavenging activity (75%). Trypsin and pepsin SPH also had high DPPH radical scavenging (85%), ABTS radical scavenging (93%) and ferric reducing (Abs700 = 1.2) abilities. Thus, metal chelating and superoxide anion radical scavenging activities of SPH are dependent on enzymes rather than DH.     

First feeding of common carp larvae on diets with high levels of protein hydrolysates

A 21 day feeding trial was carried out at 24 °C aiming to evaluate the effect of diets containing high levels of protein hydrolysates on growth, survival and body composition of common carp, Cyprinus carpio L., larvae since first feeding. Eight semipurified diets based on a fish protein hydrolysate (CPSP) with or without additional nitrogen sources, such as casein, casein hydrolysates or other hydrolysates from several origins, were tested, using a diet based on yeast as a reference. High survival rates of larvae were observed at the end of the trial for all experimental diets, ranging from 97% for the yeast diet to 71% when CPSP was used as the only nitrogen source. In terms of growth, the best results were achieved with the CPSP-casein diet (1:1) and the yeast-based diet (17.5 mm total length / 82.8 mg wet weight and 16.3 mm total length / 55.4 mg wet weight, respectively). Growth of larvae fed on diets with protein hydrolysates as the only nitrogen source was considerably lower than that of larvae fed a mixture of intact protein and protein hydrolysates.     

Rheological Behavior of Protein Hydrolysates from Papain-treated Male Gonad of Scallop (Patinopecten yessoensis)

ABSTRACT

In the present study, the rheological behavior of hydrolysates from scallop male gonad hydrolysates (SMGHs) was studied. The hydrolysates were obtained from scallop male gonads (SMGs) using papain. The changes in molecular mass of proteins in SMGHs were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that the proteins of SMGs were significantly degraded after hydrolysis with papain. The degree of hydrolysis reached to 17.8% and 20.8% for SMGHs treated by papain at 300 and 3,000 U/g protein, respectively. The SMGHs exhibited a weak strain overshoot behavior as well as non-Newtonian shear thinning flow behavior. Moreover, the rheological properties of SMGHs possessed a papain dose-dependent manner. These results suggest that SMGHs could be applied as a potential gelling and thickening agent in food formulations.     

Effects of different levels of plant proteins on the ongrowing of meagre (Argyrosomus regius) juveniles at low temperatures

Four experimental diets with different inclusion levels of plant proteins and fish protein hydrolysates were compared with a commercial diet for meagre (Argyrosomus regius) ongrowing at optimal and suboptimal water temperature. Results in terms of growth in length and weight, conversion efficiency, dietary feed intake and utilization, body composition (whole fish and liver) as well as enzyme and immunological activities are presented. Fish growth was significantly reduced by the inclusion of plant proteins, although further addition of fish protein hydrolysates improved the results. Daily feed intake was not affected by plant protein inclusion in the diets, although the group fed the highest inclusion level showed lower ingestion than the rest of the groups, probably as a consequence of a reduced dietary palatability. The decrease in water temperature during the second part of the experiment had a negative effect on feed intake and fish growth. Gross visceral morphology of meagre fed the experimental diets was not affected, but muscle weight was significantly reduced. Whole body and liver composition was not affected with plant protein inclusion. However, the inclusion of fish protein hydrolysates resulted in a significant increase in fat content, especially in liver cholesterol and steryl esters, with a parallel reduction in protein. Brush border enzymes were affected by plant protein inclusion as well as serum lysozyme that significantly increased in the fish fed the highest inclusion level. As a conclusion, up to 315 g kg^?1 plant protein (76.2% of total protein content) can be included in the diet for meagre without affecting growth or feed utilization. Higher inclusion levels can also be used if at least 5% fish protein hydrolysate is also included.