鳕鱼下颌肉水解蛋白制备工艺优化

通过单因素实验(蛋白酶种类、加酶量、料液比、水解时间、温度和pH值),对鳕鱼下颌肉进行酶解分析,以水解度(DH)为指标,确定最适蛋白酶为复合风味蛋白酶,其单因子最佳水解条件为:加酶量为1 400 U/g(相对于鱼糜质量)、料液比为1:3、水解时间为5 h、温度为43℃、pH 7.6。经正交试验验证,复合风味蛋白酶的最佳酶解工艺条件为:pH7.0,料液比1∶2,加酶量为1 400 U/g,水解8 h,DH可达42.62%。     

复合酶提取牡蛎抗氧化肽的工艺研究

以牡蛎为原料,首先从木瓜蛋白酶、中性蛋白酶、碱性蛋白酶、胃蛋白酶、胰蛋白酶中筛选出胰蛋白酶为内切酶,以水解度为指标,得到最佳的酶解工艺条件:时间4h,温度50℃,pH8.0,料水比1∶2,加酶量3％(7 500 U/g),水解度为49.50％;同时以水解度为指标,得到外切酶风味蛋白酶的最佳酶解工艺:时间5h,温度50℃,pH8.0,料水比1∶2,加酶量3％ (450 U/g),实际水解度50.95％.最后,以清除羟自由基能力和水解度为指标,探讨内切酶(胰蛋白酶)和外切酶(风味蛋白酶)不同复合酶解方式的抗氧化能力.最终确定,复合酶解制备牡蛎抗氧化肽效果最好,其酶解条件为胰蛋白酶为3％(7 500 U/g)、风味蛋白酶加酶量为3％ (450 U/g),pH8.0,时间5h,料水比1∶2,温度50℃时,水解度高达53.94％,体外清除·OH的EC50为0.56 mg/mL.     

不同水解工艺对鱼溶浆蛋白水解效果的影响

本研究采用单酶水解、复合酶水解、酸水解及酶酸耦合水解4种水解工艺对鱼溶浆进行水解,以水解度为标准确定最佳水解工艺.结果表明:单酶水解工艺中,在最优条件下(酶解温度50℃,初始pH 5,加酶量2000 U/g,固液比1:15)以中性蛋白酶酶解鱼溶浆,其水解度最高值为40.37％;复合酶水解工艺中,中性蛋白酶和碱性蛋白酶复...     

响应面法优化末水坛紫菜蛋白酶解工艺及其酶解液抗氧化活性研究

为实现末水坛紫菜(Porphyra haitanensis)的高值化利用,研究了末水坛紫菜的蛋白酶解工艺及其酶解液的抗氧化活性。以酶解产物水解度和还原力为指标,分别采用单因素和响应面优化实验筛选出最适蛋白酶和最佳酶解工艺参数;通过测定酶解液还原力对1,1-二苯基-三硝基苯肼(DPPH)自由基、羟自由基(·OH)和超氧阴离子自由基(O_2^-·)的清除作用,研究了最高水解度下的酶解液的抗氧化性活性。结果表明,中性蛋白酶是6种蛋白酶中的最适用酶;最佳酶解条件为:底物质量浓度35 g·L^-1、加酶量31 200 U·g^-1、温度45℃、pH 7.6、酶解时间5 h,在此条件下坛紫菜水解度达31.37%;酶解液还原力为2.2,对DPPH、·OH和O_2^-·自由基清除率分别为56.26%、85.84%和72.73%。结果表明,中性蛋白酶可以有效水解末水坛紫菜,水解后的酶解产物具有较好的抗氧化能力和应用前景。     

罗非鱼碎肉酶法制备蛋白胨的工艺研究

为探讨罗非鱼碎鱼肉酶法制备蛋白胨的加工工艺,采用正交试验的方法,分别研究了木瓜蛋白酶、AS.1398中性蛋白酶、复合蛋白酶水解罗非鱼碎肉制备蛋白胨的工艺条件。结果表明:木瓜蛋白酶的最佳水解工艺条件为pH6.5,温度65℃,水解时间4h,加酶量1250 U/g,蛋白胨得率达12.63%;AS.1398中性蛋白酶最佳水解工艺条件为pH 7.5,温度55℃,水解时间4 h,加酶量750 U/g,蛋白胨得率达13.25%;复合蛋白酶的最佳水解工艺条件为pH 7.0,温度50℃,水解时间4.5 h,加酶量850 U/g,蛋白胨得率达11.43%。     

异枝麒麟菜酶法降解工艺的优化研究

以施氏假单胞菌分泌的卡拉胶酶为工具,采用二次回归正交旋转组合设计,对异枝麒麟菜的酶法降解工艺进行了研究,探讨pH、温度和卡拉胶酶添加量对还原糖生成量的影响。pH、温度和卡拉胶酶添加量与还原糖生成量的数学回归模型为:Y=0.3310 0.0107Z1-0.0848Z2 0.0451Z3-0.0012Z31-0.0055Z32 0.0186Z21-0.0940Z21-0.0635Z22-0.0125Z23;最佳的酶解参数为:pH 6.27,温度39.6℃,加酶量74.4 U,底物质量浓度为0.7595 g/L(总糖含量),酶解8 h。     

酶解法提取鱿鱼肝油的生产工艺研究

以鱿鱼肝脏为原料,采用AS.1398中性蛋白酶水解提取肝油,选用提取率为指标,通过单因素试验和响应面试验法确定最佳的酶解工艺;并从其肝油的提取率、品质、脂肪酸组成方面与传统水提法进行比较.试验结果表明,最佳酶解工艺参数为:料液比1∶1,酶解pH值6,加酶量1 340 U/g,酶解温度55℃,酶解时间4h;酶提法提取率高于水提法,且过氧化值较低,鱼油品质较好.     

提取方法对淡水鱼油提取率及品质的影响

以白鲢(Hypophthalmichthys molitrix)内脏为原料,采用复合蛋白酶(Protemax)水解法提取鱼油,研究酶解条件和提取方法对鱼油提取率、品质及脂肪酸组成的影响,以获取高品质的鱼油制品.结果表明:提取方法和条件对鱼油的提取率、酸价及过氧化值(POV)均有明显影响;采用复合蛋白酶水解法提取鱼油时,其适宜的条件为酶解起始pH 7.5,酶解温度50 ℃,酶用量2 000 U/g粗蛋白,酶解时间3 h,鱼油的提取率达到85.67%,鱼油品质较好.复合蛋白酶水解法和碱性蛋白酶(Alcalase)水解法的提取率高于稀碱水解法,且复合蛋白酶水解法得到的n-3系列多不饱和脂肪酸含量更高.     

沙蜇饮料基料酶解液酶解工艺的研究

以水解度为指标,选用胰蛋白酶、碱性蛋白酶、酸性蛋白酶、中性蛋白酶、风味蛋白酶和胃蛋白酶对沙蜇进行单酶水解,确定胰蛋白酶为水解用酶。通过正交实验确定胰蛋白酶的水解条件为：温度45℃、时间5．5小时、料液比1：4．5、加酶量255U／ml、pH7．5。实验表明,适宜条件下水解度为24．59％。水解液选用柠檬酸为除腥剂,处理后的水解液腥味和涩味都有大幅度降低。     

乌贼墨黑色素粗提物的提取工艺优化及其抗氧化能力测定

本文对乌贼墨粉进行超声波辅助蛋白酶水解研究,以水解度为考察指标,筛选最适蛋白酶,并通过单因素试验和L_(16)(4~5)正交试验优化酶解条件。试验结果表明,酸性蛋白酶为墨粉水解的最佳试验用酶,最佳酶解条件为温度50℃、水解时间2 h、加酶量3.0%、反应pH 3.5、料液比1∶15,在此最优条件下对墨粉进行水解试验,制得水解后墨黑色素,并测得水解度为11.45%。水解后墨黑色素氧化产物2,3,5-三羧酸吡咯(PTCA)含量为17.621μg/mg,水解后墨黑色素总抗氧化能力为18.9 U/g,总抗氧化能力保持率为99%。     

甲壳低聚糖酶法制备工艺的优化

为制备具有较好水溶性和生理活性的甲壳低聚糖,本实验选用纤维素酶对壳聚糖进行降解,以还原糖浓度作为衡量降解效果的指标,通过单因素实验和正交实验优化酶解制备工艺,获得最佳酶解条件为:酶浓度1600U/g、温度55℃、反应时间7h、pH值5.4,在该条件下获得的酶解产物还原糖浓度为2.52mmol/L。得到的酶解液通过超滤分离,获得分子量小于10KDa的甲壳低聚糖,其产率达到69.51%。     

Antioxidant and Angiotensin-Converting Enzyme Inhibitory Activities of Protein Hydrolysates Prepared from Threadfin Bream (Nemipterus spp.) Surimi By-products

Solid wastes from threadfin bream (Nemipterus spp.) surimi production composed of head and frame were hydrolyzed by various commercial proteases (Alcalase, Flavourzyme, Neutrase, Protamex, papain, and pepsin) to produce protein hydrolysates with bioactive properties. An Alcalase-hydrolyzed sample at 24.4% degree of hydrolysis (DH) displayed the highest antioxidant activity based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP) assay, and potassium ferricyanide method. In addition, it showed an inhibitory activity toward angiotensin-converting enzyme (ACE) of 25.5%. Antioxidant activity of threadfin bream by-product hydrolysates increased with hydrolysis time and reached the highest DPPH activity after 6 h, while that hydrolyzed for 3 h showed the highest reducing power based on FRAP and potassium ferricyanide assays. In addition, ACE inhibitory activity was found to be at an optimum after 3 h of hydrolysis. The hydrolysates (1 mg/mL) also retarded oxidation of a linoleic acid emulsion system to a similar extent as 0.1 mg/mL 3-tert-butyl-4-hydroxy anisole (BHA), indicating a potential use in the food system. Protein hydrolysates from threadfin bream surimi by-products could be tailor-made to possess both antioxidant and ACE inhibitory activity through controlling DH of Alcalase-catalyzed reactions.     

Conditions for the induction of some selective enzymes from <Emphasis Type="Italic">Bacillus subtilis</Emphasis> and their hydrolysis ability against mackerel and gracilar (asparagus, <Emphasis Type="Italic">Gracilaria verrucosa</Emphasis>)

ABSTRACT:   This study was conducted to optimize the cultivation conditions for Bacillus subtilis to produce proteases, amylases and cellulase, and to further investigate the hydrolysis ability against mackerel and asparagus. The extracellular enzymes from B. subtilis after 2 and 4 days incubation in a modified medium, containing 1% skim milk, 1% soya meal, 0.25% starch, 0.25% K₂HPO₄, 0.5% NaCl and 0.05% MgCl₂ were collected for the hydrolysis of asparagus and minced mackerel, respectively. Except for the α,α-diphenyl-β-picrylhydrazyl (DPPH) scavenging ability of the hydrolyzed asparagus, the trolox equivalent antioxidation capacity and DPPH scavenging ability of both samples increased significantly ( P  < 0.05) after 1 h hydrolysis and further increased during elongated hydrolysis at 50°C. Sodium dodecylsulfate–polyacrylamide gel electrophoresis indicated severe degradation of muscle proteins during hydrolysis. Changes in reducing sugar, soluble proteins and peptides before/after hydrolysis suggested the extracellular enzymes from B. subtilis could effectively hydrolyze the mackerel or asparagus, and subsequently improve their antioxidation ability.     

Potential of Cellulase From Bacillus megaterium for Hydrolysis of Sargassum

Bacterial cellulase can be a promising biotechnological approach in seaweed degradation to facilitate extraction of bioactive molecules. In the present study, bacterial cultures were isolated from marine and terrestrial samples and screened for cellulase production. The selected cultures were grouped by random amplification of polymorphic DNA (RAPD) profiling, and the cultures showing a distinct banding pattern were identified by 16S rDNA sequence analysis. Cellulase from Bacillus megaterium (CB-sw1-I), a native isolate, was purified by ion-exchange chromatography with a purification fold of 6.91 and specific activity of 1.66 U. The purified enzyme with molecular weight of 43 kDa was optimally active at pH 6.0 and temperature of 60°C. The potentiality of enzyme in degradation of Sargassum thallus was evident with an increase in reducing sugar. Morphology of the thallus after 10 days digestion observed by scanning electron microscope also provided additional evidence for degrading ability of the enzyme. This enzyme could subsequently be used in hydrolysis of seaweed for extraction of bioactive molecules.     

基于酶技术生产低黏度及超低黏度褐藻胶的工艺

为解决当前低黏度及超低黏度褐藻胶生产工艺中存在的不足,本实验以海带为原料,利用褐藻胶裂解酶降解制备低黏度及超低黏度褐藻胶,研究了分子量、p H、温度对黏度的影响,确定了碱消化的最佳条件,探究了酶解工艺中加酶量、酶解时间及原料的初始黏度对褐藻胶产品的影响。结果显示,通过控制加酶量(100~500 U/g),酶解30 min即可得到低黏度及超低黏度褐藻胶,其中加酶量为100~330 U/g时可得到低黏度褐藻胶,加酶量增加至330~500 U/g时,可得到超低黏度褐藻胶,且酶解法得到的褐藻胶样品分子量均一度高,工艺节水率高达10%~50%;同时研究发现酶解样品黏度与原料初始黏度相关性不大,只在较短时间内表现出相关性,该工艺具有较高的原料适用性。     

Optimization of Antioxidant Peptides Production from the Mantle of Cuttlefish (Sepia pharaonis) Using RSM and Fractionation

Persian Gulf cuttlefish mantles were hydrolyzed (CPH) using alcalase, and the optimal hydrolysis parameters were obtained for the highest degree of hydrolysis (DH) and strongest antioxidant (based on their ability to quench 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals) activity using response surface methodology (RSM). The predicted optimal parameters of DH and quenching DPPH radicals was: pH of 7.88, 50.2°C, 150 min, and enzyme to substrate ratio of 1.5%. The reducing power (RP) and ability of optimized peptides to quench ABTS radicals in a gastro-intestinal track model system increased during the intestinal stage, while scavenging ability against DPPH radicals dropped (P < 0.05). The oxidation of lipid was retarded in a lecithin-liposome model added with optimized CPH in a concentration dependent response. Ultrafiltration of optimized CPH showed that the 3–10 KDa fraction had the greatest DPPH radical scavenging activity, the 10–30 KDa fraction had the highest reducing power, and the <3 KDa fraction had the greatest ABTS radical scavenging activity.     

南海鸢乌贼营养成分分析与评价

将鸢乌贼(Symplectoteuthis oualaniensis)肌原纤维蛋白与褐藻寡糖进行糖基化反应,并采用胃蛋白酶和胰酶对蛋白进行体外消化,分析糖基化改性对蛋白消化产物抗氧化活性和氨基酸组成的影响。结果显示,肌原纤维蛋白与褐藻寡糖在反应过程中自由氨基浓度显著降低,且反应前12 h降低更为明显,表明二者之间发生了明显的接枝反应。糖基化肌原纤维蛋白的DPPH自由基清除率及还原力在模拟消化前后均显著高于未接枝肌原纤维蛋白(P<0.05),因此接枝物具有更高的抗氧化能力。消化后蛋白自由基清除能力及还原力均降低。SDS-PAGE电泳图谱表明,肌原纤维蛋白与褐藻寡糖接枝反应促使高分子量蛋白接枝物的生成。酶解后糖基化肌原纤维蛋白的小分子蛋白、多肽的产生量明显增多,表明糖基化促进了蛋白水解反应。氨基酸分析显示,肌原纤维蛋白接枝物酶解液中总必需氨基酸含量减少而疏水性氨基酸含量增加。     

Optimization of Hydrolysis Conditions for Production of Angiotensin-Converting Enzyme Inhibitory Peptides from Basa Fish Skin Using Response Surface Methodology

ABSTRACT

Basa fish skin free from fat and noncollagenous proteins was hydrolyzed by different proteinases to produce angiotensin-converting enzyme (ACE) inhibitory peptides. Protamex hydrolysates were found to have the highest ACE inhibitory activity. Response surface methodology (RSM) was applied to optimize the hydrolysis conditions of Protamex—including enzyme-to-substrate ratio, hydrolysis time, and solid (fish skin)-to-liquid (water for hydrolysis)—at a temperature of 50°C and a pH of 7.0. The mathematical model demonstrated a good fit with the experimental data. An enzyme-to-substrate ratio of 6,108 U/g, a hydrolysis time of 1.24 h, and a solid-to-liquid ratio of 1:8.05 g/mL were found to be the optimal conditions to achieve the highest value of ACE inhibitory activity. The IC₅₀ of the hydrolysates for ACE inhibitory activity was 1.417 mg/mL under these conditions.     

Effect of different C/N ratios and hydraulic retention times on denitrification in saline,recirculating aquaculture system effluents

Data on operation and performance of cost-effective solutions for end-of-pipe removal of nitrate from land-based saltwater recirculating aquaculture systems (RAS) are scarce but increasingly requested by the aquaculture industry. This study investigated the performance of a (semi)commercial-scale fixed-bed denitrification unit using single sludge for treating effluent from a commercial, saltwater RAS used for production of Atlantic salmon (Salmo salar). A fixed-bed denitrification reactor was fed continuously with 3-days hydrolyzed sludge from the commercial RAS, and was operated at different hydraulic retention times (HRTs; 1.82, 3.64, 5.46, or 7.28 h) or influent C/N ratios (3, 5, 7, or 10). Twenty-four h pooled samples were collected from the inflowing RAS water and the hydrolyzed sludge as well as from the denitrification reactor outlet, and samples were analyzed for nutrients and organic matter content.Nitrate removal rates increased consistently with decreasing HRT (from 64.3 ± 5.2–162.7 ± 22.0 g NO₃-N/m³/d within the HRTs tested) at non-limiting C/N ratios, while nitrate removal efficiencies decreased (from 99.6 ± 0.3–58.2 ± 8.9 %). With increasing influent C/N ratios at constant HRT (3.64 h), nitrate removal rates increased until the removal efficiency was close to 100 % and nitrate concentration in the denitrification reactor became rate-limiting. A maximum nitrate removal rate of 162.7 ± 2.0 g NO₃-N/m³/d was achieved at a HRT of 1.82 h and an influent C/N of 6.6 ± 0.5, while the most efficient use of hydrolyzed sludge (0.19 ± 0.02 g NO₃-N removed/g sCOD supplied) was obtained with a HRT of 3.64 h and a C/N ratio of 2.9. Removal rates of organic matter significantly and consistently increased with decreasing HRT and increasing C/N ratio. In addition, reducing HRT and increasing C/N ratios significantly improved removal of total phosphorus (TP) and PO₄-P.In conclusion, optimal management of the operating parameters (HRT and C/N ratio) in a single-sludge denitrification process can significantly reduce the discharge of nitrogen, organic matter, and phosphorous from land-based saltwater RAS and thus contribute to increased sustainability.