【作者】 童彦；

【导师】 应铁进；

【作者基本信息】 浙江大学 ， 食品科学， 2013， 博士

【摘要】 中国有着全世界最丰富的淡水鱼资源,淡水鱼类有七百多种,其中主要经济鱼类有四五十种。鳙鱼(Aristichthvs nobilis),又称花鲢、胖头鱼,广泛分布于中国淡水水域,是最常见的重要经济鱼种之一。鳊鱼通常为鲜食,鱼肉和鱼皮皆为食用部位,但鱼骨、鱼鳞等占鱼体50-70%的部分都会作为废弃物被抛弃,造成资源的浪费和环境的污染。随着中国淡水鱼加工产业的不断发展,对这些废弃物的合理开发利用成为其中一个重要的问题。从这些废弃物中提取胶原蛋白和其他有效物质,对解决因鱼下脚料引起的资源浪费和环境问题以及增加鱼产品利用率、提高淡水鱼产业的经济价值都有重大的意义。本文分析了鳙鱼鱼鳞的营养成分组成：蛋白质含量为60.19%,灰分含量为25%,水分含量为13.40%。由于灰分中羟基磷灰石的存在不利于胶原蛋白的提取,需要对鱼鳞进行脱钙处理。在对脱钙工艺进行优化后得到最佳工艺为EDTA-2Na浓度0.4mol/l,液料比30：1,时间8h,可脱除占鱼鳞17.56%的钙。本文优化了乙酸提取胶原蛋白和胃蛋白酶提取胶原蛋白的提取工艺,在乙酸浓度0.5mol/l、液料比30、提取时间72h的条件下,酸溶性胶原蛋白的提取率为1.31%±0.31%,酶浓度1250U/g、液料比30、提取时间48h的条件下,酶溶性胶原蛋白的提取率为1.79+0.28%。对酸溶性胶原蛋白和酶溶性胶原蛋白的一级结构、二级结构进行了分析。氨基酸组成分析表明,胶原蛋白含量最丰富的氨基酸是甘氨酸,达24%,其次是脯氨酸、谷氨酸、丙氨酸,还含有比较丰富的精氨酸。红外光谱扫描发现两种胶原蛋白含有α螺旋结构,其螺旋结构保持完好。两种胶原蛋白的变性温度都为32.5℃,比大多鱼鳞胶原蛋白的变性温度高。胶原蛋白变性水解后会形成明胶,明胶的凝胶强度是其重要的质量指标之一,实验采用响应面试验设计对鱼鳞明胶的提取条件进行了优化,其最佳提取工艺为提取温度46.98。C,时间1.27h,pH4.00以及酶浓度547U/g,得到较高凝胶强度的鱼鳞明胶,最大凝胶强度为318+7g(p<0.01),比热水提取明胶的凝胶强度(216+3g,p<0.01)高。将鱼鳞明胶和猪皮明胶进行了比较。对氨基酸组成的分析表明,鱼鳞明胶和猪皮明胶在苏氨酸、甲硫氨酸、异亮氨酸、苯丙氨酸和赖氨酸的组成上有极显著的差异,在羟脯氨酸、甘氨酸、丙氨酸的组成上有显著差异。鱼鳞明胶的羟基化程度(32.72±0.15%)低于猪皮明胶的羟基化程度(34.24±0.17%),亚氨基酸含量(20.75±0.82%)也低于猪皮明胶的亚氨基酸含量(24.01±-0.70%)。对鱼鳞明胶的流变性分析发现,鱼鳞明胶有着优于猪皮明胶的成胶能力,但其热稳定性较猪皮明胶差.利用木瓜蛋白酶和胃蛋白酶双酶对鱼鳞明胶进行分步水解,水解产物对血管紧张素转化酶(ACE)的半抑制浓度IC5o为864μg/ml。木瓜蛋白酶水解产物和胃蛋白酶水解产物经超滤后,分子量范围<5KD的肽部分的IC50达331μg/ml。进一步葡聚糖凝胶柱分离,得到两个组分,其中Ⅱ组分的IC50达107μg/ml。本文还探索了利用美拉德反应改善鱼肉水解液风味的处理技术。获得美拉德反应的最佳条件,葡萄糖添加量3.75%、反应温度120℃、pH9.5、反应时间100min。美拉德反应前后变化较明显的氨基酸主要有：精氨酸(减少74.44%)、赖氨酸(减少65.50%)和酪氨酸(减少42.50%)。美拉德反应产物中含量较丰富的氨基酸有谷氨酸、天门冬氨酸。更多还原

【Abstract】 China has the richest freshwater fish resources around the world, more than700species, including40-50commercially species. Bighead carp (Aristichthys nobilis), distributed in South and East China, is one of the most commonly commercially produced fresh water fish in China. The fish meat and skin are used for human food, leaving almost50-70%wastes such as bone and scale. With the rapid expansion of the fish food process industry in Southeast China, the wastes disposal poses a big environmental challenge. The extraction of gelatin or other bio-materials from these production wastes might be a promising solution in terms of both reducing environment pollution and increasing the economic efficiency of the industry.Nutritional components of bighead carp scale were analyzed with protein60.19%. ash25%, and moisture13.40%. Considering the difficulty to extract the collagen together with the existence of hydroxyapatite in ash. decalcification process was necessary before extraction.17.56%of Calcium was decalcified with the optimal extraction conditions of0.4mol/l EDTA-2Na,30:1ratio of solution to sample and8h.Optimal collagen extracting processes using acetic acid and pepsin were also analyzed during the study. The results showed that extraction rate for collagen reached1.31%±0.31%under the condition of acetic acid concentration of1250U/g, liquid to solid ratio of30:1and extraction time of2hours and pepsin concentration of0.5%. liquid to solid ratio of30:1and extraction time of2hours for the optimized conditions for pepsin extraction method with the highest extraction rate of1.79±0.28%.Primary and secondary structures of acid-soluble collagen and pepsin-solubilized collagen were analyzed in the study. The amino acid composition analysis showed that the content of Glycine is over24%which is the most abundant component, and poline, glutamic acid, alanine, arginine are of significant proportions. Structure of a helix was determined by using infrared scan. Denatured temperature of protein was32.5℃which was higher than the other kinds of collagen of fish species.Gelatin can be gained after hydrolyzing the denatured collagen. The process conditions for gelatin extraction from scale are identified by using Response surface experiments. Under the conditions of extraction temperature of46.98℃,2h, pH4.00and enzyme concentration of547U/g, the maximum gel strength can reach318±7g (p<0.01) comparing to (216±3g, p<0.01) using hot water method.The comparison study of gelatin from scale and pigskin indicates high significant composition differences of threonine, isoleucine, methionine and phenylalanine and lysine and significant differences of hydroxyproline, glycine, alanine. Bighead carp scale gelatin showed lower imino acid (Proline and Hydroxyproline) content (20.75±0.82%) than pig skin gelatin (24.01±0.70%). Assessment on dynamic viscoelastic properties indicated that bighead carp scale gelatin had better gelling ability and lower thermo-stability than pig skin gelatin.Using papain and pepsin, we got the bighead carp scale gelatin hydrolysate which can inhibite the activity of angiotensin converting enzyme (ACE), with ICsoof864μg/ml. After ultrafiltration, we got the fraction of molecular mass lower than5KD with IC50of331μg/ml. Then the fraction of molecular mass lower than5KD was isolated by Sephadex G25to afford one part with IC50of107μg/ml.We studied the technology of improving the flavor of bighead carp hydrolysate by Maillard reaction. The optimal conditions for sensory evaluation are9.5for reaction pH,120℃for reaction temperature,3.75%for the glucose, and100min for the time of reaction. Amino acid analysis shows that the main amino acids changed much during the reaction are:arginine (reduced74.44%), lysine (reduced65.50%), and tyrosine (reduced42.50%), which may be the key amino acids taking part in the maillard reaction.更多还原