低值鱼酶解液生化变化与品质关联初探

系统地研究了低值鱼水解过程中pH、TVB-N、组胺与细菌总数的变化。研究表明,正常的水解过程中,pH不断降低,从6.5下降到6.1,挥发性氮和组胺含量基本保持不变,细菌总数在水解初期有大幅度降低,从5.4×106下降到1000～3000;不正常的酶解过程中,酶解液pH先降低后升高,挥发性氮和组胺含量分别从16.7mg/100mL和1.2mg/100mL升高到450mg/100mL和120mg/100mL,细菌总数从5.4×106升高到4.2×108。此外,细菌大量繁殖还导致水解液中氨基酸含量降低,特别是Phe、Leu的降低尤为明显。      

低值鱼的酶解及口味评判

在这篇文章中 ,我们研究了利用内肽酶和端解酶复合酶解的条件 ,并对不同时间的酶解液进行了口味评判 ,得出结论 :低值鱼酶解的最佳酶解条件为 5 5℃ ,pH7.0 ,复合蛋白酶与风味蛋白酶按 1:2的比例分部加酶 ,酶解时间 30～ 4 8小时酶解效果最好。     

低值鱼的酶解及品味评判

在这篇文章中，我们研究了利用内肽酶和端解酶复合酶解的条件，并对不同时间的酶解液进行了口味评判，得出结论：低值鱼酶解的最佳酶解条件为55℃，pH7．0，复合蛋白酶与风味蛋白酶按1：2的比例分部加酶，酶解时间30～48小时酶解效果最好。     

低值鱼的酶解及口味评判

在这篇文章中,我们研究了利用内肽酶和端解酶复合酶解的条件,并对不同时间的酶解液进行了口味评判,得出结论低值鱼酶解的最佳酶解条件为55,pH7.0,复合蛋白酶与风味蛋白酶按12的比例分部加酶,酶解时间30～48小时酶解效果最好。     

低值鱼的深度酶解及海鲜复合调味料的生产

以低值鱼(海产小杂鱼、罗非鱼下脚料及小鲫鱼的混合物)为原料,综合氨基氮、挥发性盐基氮及感官评分等指标,筛选出适宜的蛋白酶及酶解工艺,制备出风味鲜美、安全卫生的酶解液,并以此为基料开发出海鲜复合调味料。结果表明:适宜的酶解方式为双酶两步水解法(Alcalase单酶水解2h后加入Flavourzyme),酶解时间为8h,振荡酶解与静止酶解对低值鱼的酶解效率影响不大;低值鱼经双酶酶解后,酶解液中氨基氮含量可达0.43g/dL,挥发性盐基氮为12.33 mg/dL,细菌总数为5.4×104 cfu/mL;以酶解液为基料开发复合调味料口感自然,滋味宜人,具有广阔的市场前景。     

不同种类低值鱼酶解效果的比较及优化

本文对比了不同海洋低值鱼的蛋白质含量和酶解效果,并对青鳞鱼和斑鲦的酶解方案进行优化。结果表明：蓝园鳕和青鳞鱼的蛋白质含量较高,为17％以上;斑鲦、黄鲫、刺鲳、鲻鱼、鳓鱼的蛋白质含量为15～16％。但蓝园鳕、黄鲫、刺鲳、鲻鱼的酶解效果较好,青鳞鱼、斑鲦和鳓鱼的酶解效果较差。青鳞鱼的最佳酶解方案为：木瓜蛋白酶0．05％,风味蛋白酶0．1％,水解蛋白酶0．05％,胰蛋白酶0．15％,可提高蛋白质利用率为86．07％,氨基酸转化率为49．24％,酶解清液出品量为11．30mL。斑绦的最佳酶解方案为：木瓜蛋白酶0．15％,风味蛋白酶0．1％,水解蛋白酶0．05％,胰蛋白酶0．15％,可提高蛋白质利用率为83．22％,氨基酸转化率为49．14％,酶解清液出品量为10．91mL。     

海产低值鱼酶解过程中呈味物质变化趋势的研究

研究了低值鱼酶解过程各种呈味成分的变化趋势及其对酶解液呈味的影响.结果表明,氨基酸、多肽分子量和含量的变化是酶解液呈味变化的主要原因.酶解液中多肽含量在酶解3小时后达到最高值0.635g/100mL,随后逐渐降低为0.49g/100mL;氨基酸含量在酶解过程中始终不断增加,40小时后达到0.67g/100mL.酶解前3小时以生成多肽为主,后期以多肽降解为游离氨基酸为主,其中苦味氨基酸较鲜味氨基酸先释放出来.总酸和总糖在酶解前3小时即释放出来,并在水解过程含量逐渐降低,有机酸对呈味的贡献是增强呈味、提高缓冲能力,总糖对酶解液呈味贡献不大.     

海产低值鱼酶解过程中呈味物质变化趋势的研究

研究了低值鱼酶解过程各种呈味成分的变化趋势及其对酶解液呈味的影响.结果表明,氨基酸、多肽分子量和含量的变化是酶解液呈味变化的主要原因.酶解液中多肽含量在酶解3小时后达到最高值0.635g/100mL,随后逐渐降低为0.49g/100mL;氨基酸含量在酶解过程中始终不断增加,40小时后达到0.67g/100mL.酶解前3小时以生成多肽为主,后期以多肽降解为游离氨基酸为主,其中苦味氨基酸较鲜味氨基酸先释放出来.总酸和总糖在酶解前3小时即释放出来,并在水解过程含量逐渐降低,有机酸对呈味的贡献是增强呈味、提高缓冲能力,总糖对酶解液呈味贡献不大.     

低值鱼蛋白酰化改性与其酶解特性关系的研究

本文选用低值鱼蛋白进行酰化改性,研究其改性程度与酶解特性(酶解物氨态氮得率,TCA可溶性肽得率及肽分子量分布)间的关系.结果表明:酰化鱼蛋白导致氨态氮得率下降,但有利于TCA可溶性氮得率的提高.最终得到60℃/30min热处理后0.3 g SA/g Pro改性的鱼蛋白酶解10 h,TCA可溶性肽得率最高达38%.     

Biochemical and nutritional changes in fish proteins during drying

Biochemical and nutritional changes in the muscle proteins of a lean marine fish Nempiterus japonicus during drying at 50, 60 and 70°C were investigated. Solubility of proteins in water, 0.6 M NaCl, 1.5 M urea, 8 M urea and 10 g litre^?1 sodium dodecyl sulphate (SDS) decreased as drying progressed at all three temperatures; most of the decrease occurring in the initial 4 h of drying SDS-polyacrylamide gel electrophoresis of 1.5 M urea, 8 M urea and SDS extracts showed that higher molecular weight (MW) protein fractions were more sensitive to drying and disappeared much earlier from electropherograms than the lower MW protein fractions. Residual solubility of proteins near the pH range of 4–6 was found to increase during drying, but solubility at acid and alkaline pH was adversely affected. Decrease of solubility by drying was more affected at acid pH, especially at higher temperatures than at alkaline pH. Sulphydryl groups registered a regular and sharp decrease with drying except at 50°C, where initially an increase was observed. Apart from disulphide and hydrophobic bonds, free amino groups also appear to be involved in denaturation reactions during drying. Pepsin digestibility of fish muscle decreased slightly during drying but a clear relationship with drying temperature was not evident. Highly significant differences in proteins between protein efficiency ratio (PER), net protein utilisation (NPU) and biological value were observed between the drying temperatures. The PER and NPU of fish dried at 60°C were significantly higher than those dried at 50 or 70°C.     

贮运温度对包装鲜草鱼肉TVB-N的动态变化影响研究

采用高、低两种阻隔包装材料及真空、普通两种包装方式包装鲜鱼肉,研究了在不同的贮存温度下,包装鲜草鱼肉挥发性盐基氮（TVB-N）的增加量随存放时间的变化规律及数学关系式。结果表明,不同贮存温度下,包装鲜草鱼肉的TVB-N增加量（Y）与贮存时间（t）符合Y=A·tB关系式,其中系数A、B与包装方式和贮存温度有关,且与温度T符合A=c+f·EXP（T/g）,B=a+b·EXP（lnQT/d）关系式,系数c、f、a、b均与温度和包装方式有关,系数g只与包装方式有关,系数d与贮存温度和包装材料的透氧量有关。      

Acceptability of crackers ('Keropok') with fish protein hydrolysate

Proteins from Oreochromis mossambicus , a freshwater fish, were hydrolysed, using alkalase 0.61, to produce a soluble, spray-dried hydrolysate. The hydrolysis was carried out at 50°C, using a ratio of one part water and one part fish mince, an enzyme:substrate ratio of 1:50 at pH 8.0. Reaction was terminated by heating to 90°C for 20min. After neutralization, the soluble fraction obtained after centrifugation was spray dried in a mini spray-drier, at an air inlet temperature of 170°C and a feed rate of 41⁻¹. The spray-dried hydrolysate was incorporated into crackers which are fried before eating. Ten per cent hydrolysate was found to give maximum linear expansion. Sensory evaluation with 20 experienced assessors showed that in terms of appearance, crispiness and colour, crackers with hydrolysate had the highest scores, compared to crackers made with O. mossambicus and Sciaena sp. (Jewfish). There were no significant differences in overall acceptability in all three samples. Crackers with hydrolysate also had the highest nitrogen content.     

Postmortem changes in cazon fish muscle stored on ice

The biochemical, chemical and physical postmortem changes and their relation to the cazon muscle eating quality were studied during an 18 day storage period at 0 °C (ice). Content of ATP and breakdown products, K value, pH, trimethylamine (TMA-N), total volatile bases (TVB-N), water-holding capacity (WHC), colour and texture changes were examined. At the beginning of the study, the cazon muscle showed a low concentration of ATP and a high value of IMP. Regarding to the signs of freshness and deterioration, K value presented a linear increase (r² = 0.97) with an initial value of 1.05% and a final value of 58.9%. The TBV-N and TMA-N significantly increased (P < 0.05). As for the physical analysis whereas the pH and the WHC changed (P < 0.05); texture was not affected (P < 0.05). The overall results of this study indicated that the edible quality of cazon fish muscle was maintained during at least 18 days of ice storage.     

不同保鲜剂对4 ℃冷藏鲶鱼鱼糜保鲜效果的影响

从几种天然保鲜剂中选取一种能够脱除鲶鱼鱼糜的土腥味并且抑制其鲜味降解的保鲜剂,以提高鲶鱼鱼糜
的经济价值和食用安全性。在5 份等质量鲶鱼碎肉中分别添加质量分数为0.5%血浆蛋白、0.5%鱼骨肽、10%壳聚糖
＋0.3%茶多酚复合剂、12.5%乳清蛋白、1%干酵母＋0.3%葡萄糖复合剂5 种天然保鲜剂,托盘包装并于4 ℃冷藏。
选取冷藏过程中pH值变化的3 个关键点（起始点、极限pH值点和pH＞7.0的鱼肉腐败点）,在这3 个关键点测定鱼
糜的硫代巴比妥酸反应物（thiobarbituric acid-reactive substances,TBARS）值、挥发性盐基氮（total volatile basic
nitrogen,TVB-N）值、微生物等指标的变化情况。结果发现,鲶鱼鱼糜中添加0.5%鱼骨肽可以延长鲶鱼鱼糜达到极
限pH值的时间,且TVB-N值、TBARS值及细菌总数均低于其他组。0.5%鱼骨肽对鲶鱼鱼糜的保鲜效果最好。     

鲫鱼蛋白酶解制取鱼露及其降胆固醇活性研究

以鲫鱼为原料,利用蛋白酶解技术制取富含多肽的酶解物,并以酶解物为基本原料制备调味品鱼露。通过对胆固醇胶束溶解度的抑制作用,研究其降胆固醇的活性。结果表明,最佳酶解条件为时间5.40h,加酶量109.67U/mL,温度40.23℃,此时胆固醇胶束溶解度抑制率为53.129±0.670%,与预测值54.617±0.240%相吻合。在此条件下,制得的鱼露风味佳、营养高,且具有较好的降胆固醇活性。     

罗非鱼蛋白酶解制取鱼露及其抗氧化研究

目的:以罗非鱼为原料,采用生物酶解技术加工传统产品鱼露,提高产品质量,缩短加工时间。方法:采用枯草杆菌碱性蛋白酶(E1)、风味酶(E2)酶解罗非鱼蛋白,制取富含多肽的酶解物;并以酶解物为基本原料制备调味品鱼露。通过对自由基的清除作用,研究其抗氧化作用。结果:采用生物酶解技术生产罗非鱼鱼露,产品色泽好,风味浓,营养高,有良好的抗氧化性。结论:与传统技术生产鱼露比较,生产时间短,工艺条件容易控制,产品质量稳定,该研究为罗非鱼到深加工提供了理论基础。