近江牡蛎的超声波辅助自溶及酶解条件研究

超声波和蛋白酶可以破坏蛋白质结构,提高短肽的得率。本试验以近江牡蛎为原料,在适度水解、控制挥发性盐基氮在合理范围的前提下,以短肽含量为主要目标,首先通过研究超声波功率、时间对牡蛎自溶酶解的影响,优化超声波辅助酶解工艺,然后采用单因素试验研究碱性蛋白酶对超声波—自溶酶解液酶解效果的影响。结果显示,440 W超声波处理牡蛎10min后自溶酶解,短肽含量为(88.75±1.16)mg/mL,是对照组的2.12倍;水解度为(30.38±0.05)%;挥发性盐基氮为(79±2)μg/g。采用碱性蛋白酶对超声波-自溶酶解液进行进一步酶解,优化的酶解条件是:加酶量5kU/g,酶解温度55℃,酶解时间4h,此时短肽含量达到100mg/mL以上,水解度为(35.95±0.05)%;挥发性盐基氮为(178±6)μg/g,处在可接受范围。试验结果表明,超声波预处理后自溶,再进行外源蛋白酶酶解可显著提高酶解效率。     

不同酶解条件对鳀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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4 2 %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。     

木瓜蛋白酶对罗非鱼下脚料的水解作用

试验结果表明,木瓜蛋白酶水解罗非鱼下脚料蛋白的适宜条件为:底物浓度1∶1.5,温度60℃,加酶量1100 IU/g原料,初始pH,酶解3 h;最佳水解条件下的酶解液氨基态氮含量达1.25 g/L,蛋白质含量5.19%,氮回收率为69.88%。酶活力下降是酶解反应减缓的主要原因之一。     

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%。     

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...     

梅童鱼内源蛋白酶自水解工艺的优化

为提高海捕低值鱼加工利用率,合理利用鱼糜及鱼糜制品加工中的副产物,充分利用鱼类自身内源酶,寻求低值鱼精深加工的低碳高效利用,以梅童鱼(Collichthys lucidus)为研究对象,利用鱼类自身的内源蛋白酶将鱼体内的蛋白质酶解,在自然p H条件下,观察了液料比、自溶温度、时间对梅童鱼蛋白水解的影响,以可溶性蛋白/总蛋白的值为响应值,采用响应面分析优化自溶条件。通过求解回归方程得到的最优自溶条件为:液料比3.4,温度53℃,时间267 min。经过验证,可溶性蛋白/总蛋白的值为18.35%,与回归方程的预测值18.55%相比,相对误差1.1%,说明模型能较好地预测自溶过程中可溶性蛋白/总蛋白的值。在此条件下,测得水解度为15.84%,过0.45μm微滤膜蛋白质量比为9.83%。研究表明,该水解工艺可为生产鱼露、活性肽、氨基酸等提供技术依据。     

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。     

紫菜活性肽复合酶法制备与清除羟自由基作用

以条斑紫菜为原料,利用胰蛋白酶和木瓜蛋白酶组成的复合酶水解紫菜蛋白制备生物活性肽并研究清除羟自由基作用。采用单因素试验考察胰蛋白酶与木瓜蛋白酶的比例、底物质量浓度、酶用量、水解温度、水解时间、pH对羟自由基清除率及水解度的影响,响应面法优化酶解条件,SephadexG-15凝胶层析法测定活性肽的分子质量分布。试验结果表明,复合酶最佳酶解工艺条件为胰蛋白酶与木瓜蛋白酶复合酶比例1.67,底物质量浓度20mg/mL,酶用量1.67%,pH 7.0,温度55℃,酶解4h,紫菜活性肽对羟自由基的清除率为80.6%,清除率为50%时的质量浓度为0.744mg/mL,分子质量大多分布于500～1500ku。     

木瓜蛋白酶在制取斑鰶鱼蛋白中的应用

为确定木瓜蛋白酶酶解斑鰶鱼的条件。研究了酶解温度、酶浓度、酶解时间、加水量、pH值对斑鰶鱼氨基氮含量和总氮得率的影响。结果表明：温度小于55℃。随着酶解温度的提高、酶浓度的增加、酶解时间的延长斑鰶鱼酶解液氨基氮含量和总氮得率均增加;pH值对水解效果及氮回收率影响不大。综合考虑,最佳水解条件为：温度55℃。加酶量6．0‰。酶解时间1．5h．原料：水=1：2．5,pH值6．8。此时。氨基氮生成率达26．7％。总氮得率2．28％。     

壳聚糖固定化胰蛋白酶制备牡蛎肽的研究

以壳聚糖为载体固定化胰蛋白酶,制备牡蛎肽,然后以肽得率为指标,分别研究了pH值,酶加量,酶解时间和温度等单因子对固定化胰蛋白酶酶解牡蛎蛋白质的影响。实验结果表明,酶解牡蛎蛋白的最佳工艺条件是:底物浓度为200μg/mL,加固定化胰蛋白酶量7mg/3mL,酶解时间3h,pH 8.0,温度40℃。在此条件下水解牡蛎蛋白,肽得率可达到20.39%。     

Use of Hydrolysates from Silver Carp (Hypophthalmichthys molitrix) Head as Peptone for Vibrio anguillarum and Optimization Using Response Surface Method (RSM)

The objective of this study was to produce fish peptone (FP) from silver carp (Hypophthalmichthys molitrix) heads by Alcalase® hydrolysis in order to use for growing Vibrio anguillarum instead of the standard peptones applied in the commercial media. An optimization of the FP to be used as culture media was also carried out using the response surface method (RSM). According to the results, the degree of hydrolysis and protein percentage after 24 h was 37.68 mg/mL and 20.74%, respectively. The adjustment of the quadratic model with the experimental data was satisfactory. The analysis of variance showed a high coefficient of determination value (0.930). The results of fish protein hydrolysates also showed that fish by-products modified by enzymatic procedures can be used as low cost nitrogen sources for bacterial growth.     

Responses of digestive enzymes and body lipids to weaning times in yellowtail kingfish Seriola lalandi (Valenciennes, 1833) larvae

The optimal time to wean fish larvae from live feed to artificial feed was explored in yellowtail kingfish Seriola lalandi (YTK). The same weaning regime started at five different days post hatching (DPH), namely 10 DPH (W10), 13 DPH (W13), 16 DPH (W16), 19 DPH (W19) and 22 DPH (W22). The activities of trypsin, lipase and alkaline phosphatase were detected in fish from 8 DPH throughout the experiment, but pepsin activity was first detected in fish on 15 DPH in the W10 and W13 treatments. The increase in pepsin activity was concomitant with the decrease in trypsin activity. Total fish lipids after weaning reduced by 40% in the W10 and W13 treatments, and increased by 20% in the W19 and W22. Fish survival rate in the W22 treatment was significantly higher than that in the W10 and W13 treatments. The results suggest that 16 DPH is the earliest day to wean and the best weaning window for YTK larvae should be 19–22 DPH. This study provides enzymatic evidence to guide the weaning process for YTK larvae, and offers a useful approach to explore optimal weaning time for fish larvae.     

舌状蜈蚣藻蛋白质的提取及其抗氧化活性研究

该研究以舌状蜈蚣藻(Grateloupia livida)为原料,以蛋白质提取率为指标,探究不同破壁技术对舌状蜈蚣藻蛋白质的提取效果,并通过单因素分析和正交试验对超声波辅助水提法进行工艺优化,所得蛋白质经硫酸铵盐析法粗提纯后考察其体外抗氧化能力。结果显示,溶胀法、反复冻融法、珠磨法的最高蛋白质提取率分别为(29.66±0.86)%、(24.52±0.04)%、(26.52±0.79)%,均低于超声波辅助水提法;超声波辅助水提法提取舌状蜈蚣藻蛋白质的最佳工艺为:液料比160 mL·g^?1,超声全程时间60 min,超声功率1440 W,pH 6.0,此条件下蛋白质提取率可达58.16%;舌状蜈蚣藻粗蛋白质量浓度在1~8 mg·mL^?1内均具有较强抗氧化活性,其质量浓度为8 mg·mL^?1时的还原力为0.43±0.01,对1,1-二苯基-2-三硝基苯肼(DPPH)自由基的半数清除浓度(IC50)为4.00 mg·mL^?1,对2,2'-二氮-双(3-乙基苯并噻唑-6-磺酸)(ABTS)自由基的IC50为3.96 mg·mL^?1。     

Impact of microwave-assisted enzymatic hydrolysis on functional and antioxidant properties of rainbow trout <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis> by-products

Fishery by-products can be better utilized following enzymatic hydrolysis treatment to produce fish protein hydrolysates (FPH) with potentially enhanced interface-stabilizing properties (e.g. functionality). The production of FPH could be accelerated through the application of rapid heating methods [e.g. microwave-assisted heating (MW)] rather than slower conventional heating (CH) treatments. The objective of this study was to investigate the effects of microwave heating during enzymatic hydrolysis on the functionality and antioxidant properties of FPH. Trout by-products were hydrolyzed with Alcalase at an enzyme substrate ratio (E:S) of 0.5, 1.7, and 3.0% (w/v), respectively, for 3, 5 and 15 min using a microwave system (1200 W, 20% power with 50% duty cycle at 50–55 °C) and a conventional heating method (water bath at 50 °C). The degree of hydrolysis and protein solubility was higher (P < 0.05) for the MW-FPH than for the CH-FPH. MW-FPH at 5 min (0.5% E:S) demonstrated higher (P < 0.05) emulsifying activity and emulsion stability than CH-FPH with the same treatment. Foam capacity and stability were also greater (P < 0.05) for MW-FPH samples that were treated 15 min by microwave-assisted heating (0.5% E:S) when compared to CH. Overall, MW-FPH exhibited higher (P < 0.05) 2,2-diphenyl-1-picryhydrazyl and ferric ion reducing capacity than CH-FPH. We therefore conclude that microwave-assisted hydrolysis is an alternative method to produce FPH with improved solubility, emulsifying activity, foaming properties and antioxidant activity.     

仿刺参性腺酶解过程风味变化

生物酶解是提高水产品蛋白质利用率的有效手段，且酶解过程往往伴随肽类、氨基酸、小分子挥发性成分等的生成或反应，进而引起酶解液风味变化。仿刺参(Apostichopus japonicus)性腺富含蛋白质和多种功效成分，具有良好的开发利用前景。为探究仿刺参性腺酶解过程中蛋白质和风味的变化规律，采用中性蛋白酶对其进行酶解，对酶解过程中可溶性蛋白质、氨基酸态氮、游离氨基酸组成、挥发性成分的变化情况进行了检测分析。结果显示，仿刺参性腺匀浆液中可溶性蛋白质和氨基酸态氮的初始含量分别为1.14和0.15 g/100 g，可溶性蛋白质在酶解前30 min内迅速增加，之后基本保持不变，氨基酸态氮含量在前90 min内随时间延长而逐渐增加，90 min后略有下降，90 min时水解度最大，达43.66%。随着酶解时间的延长，酶解液的鲜味有所增强，腥味减弱，甜味和苦味也略有增强。酶解后游离氨基酸含量显著增加(P<0.05)，其中，呈鲜味的谷氨酸含量最高，其次为呈甜味的甘氨酸和丙氨酸。仿刺参性腺酶解过程气味发生明显变化，烃类种类和相对含量均明显增加，二甲基硫醚含量显著降低，这可能是酶解液腥味减弱的主要原因     

超声波优化辅助盐渍海蜇脱铝工艺

为探究超声波辅助盐渍海蜇脱铝工艺的条件,实验以盐渍海蜇为原料,采用电感耦合等离子体质谱法（ICP-MS）进行检测,其铝残留量为考察指标,通过单因素实验研究复合保鲜液浓度、超声功率、超声频率以及超声时间对盐渍海蜇脱铝效果的影响,根据Box-Behnken中心组合实验设计,采用响应面分析法分别优化复合保鲜液脱铝工艺与超声波辅助脱铝工艺。结果显示,未超声波辅助处理的优化条件：料液比1∶7（g/mL）、浸泡时间4 h、浸泡次数3次,铝残留量最低为126.4 mg/kg,浸泡时间影响最为显著;超声波辅助处理影响脱铝率大小的因素依次为超声时间 > 超声功率 > 超声频率 > 复合保鲜液浓度;其最佳工艺：超声频率28 kHz、超声功率272.6 W、复合保鲜液[V（醋酸）∶m（丙酸钙）=1∶2]浓度0.68%、脱除时间35 min,铝残留量为124.46 mg/kg,脱铝率达到85.3%;验证实验得到实际脱铝率为82.1%,与理论预测值相比,其相对误差约为3.2%。研究表明,与未超声波辅助相比,铝脱除率稳定,脱除时间由12 h缩短至1.75 h,工艺效率提高6.9倍。因此,超声波技术应用到海蜇产业将为高效开发低铝盐渍海蜇制品提供理论依据。     

Production of High Quality Fish Oil by Thermal Treatment and Enzymatic Protein Hydrolysis from Fresh Norwegian Spring Spawning Herring By-Products

There is an increasing demand for omega-3 containing fish oils. By-products from fish fillet production can be utilized for the production of fish oils and be a valuable source of omega-3 for human consumption. The aim of this work was to evaluate industrial processes for production of quality oil for human consumption made from Norwegian spring spawning herring by-products. A mobile production plant was used to compare two industrial processes, thermal treatment (wet rendering) and enzymatic protein hydrolysis, for production of oil from herring by-products immediately after filleting. Results show that high quality herring oil can be produced from fresh by-products. The use of by-products immediately after filleting resulted in a low amount of free fatty acids for all the produced oils (below 0.4%). Thermal treatment at 70°C resulted in an oil with lower oxidation status and higher stability compared to the oils produced by enzymatic protein hydrolysis. Nevertheless, both processing methods gave a crude oil of high quality compared to crude oils on the market.     

Antioxidative Activitiy of Protein Hydrolysate from the Muscle of Common Kilka (Clupeonella cultriventris caspia) Prepared Using the Purified Trypsin from Common Kilka Intestine

Trypsin from the intestine of common kilka (Clupeonella cultriventris caspia) was purified using ammonium sulfate precipitation (30–50% saturation), Sephadex G-75, and DEAE-cellulose chromatography with the purity of 30-fold and the yield of 12%. The molecular weight of trypsin was estimated to be 23.2 kDa based on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The trypsin had optimal activity at pH 8.0 and 60°C using N-α-benzoyl-DL-arginine-ρ-nitroanilide hydrochloride (BAPNA) as a substrate and showed high stability in the pH range of 7.0–10.0. It was stable up to 50°C. Soybean trypsin inhibitor (SBTI) and N-ρ-tosyl-L-lysine-chloromethylketone (TLCK) significantly inhibited trypsin activity (p < 0.05). Protein hydrolysate from common kilka muscle with different degrees of hydrolysis (DHs; 20, 30, and 40%) was prepared using the purified trypsin, and antioxidative activities were determined. 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, ferric reducing antioxidant power, and ferrous chelating activity of hydrolysate increased with increasing DH up to 40% (p < 0.05). Therefore, trypsin from intestine of common kilka could be used as a processing aid for production of fish protein hydrolysate with antioxidative activity.