【作者】 荣建华；

【导师】 熊善柏；

【作者基本信息】 华中农业大学 ， 食品科学， 2015， 博士

【摘要】 脆肉鲩(Ctenopharyngodon idellus C. et V)是将草鱼(Ctenopharyngodon idellus)长时间饲喂蚕豆所获得的一种商品鱼,因其肌肉煮熟后质地紧实、爽脆,滋味鲜美,深受消费者的喜爱。脆肉鲩肌肉质构特性受加工处理的影响较大,100℃蒸煮处理可使肌肉的脆性增强,冷冻或较高温度的热处理则会导致肌肉脆性的下降甚至丧失,然而有关冷冻和热加工对脆肉鲩肌肉特性的影响及其机制的研究却鲜见报道。本文以脆肉鲩、草鱼为对象,采用TPA、LF-NMR、SEM、动态流变仪、电子鼻、电子舌、GC-MS、2-DE等现代分析技术,研究了冷冻、热加工对脆肉鲩肌肉微观形貌、质构特性、持水性、粘弹性、风味以及蛋白质功能特性的影响,并分析了脆肉鲩和草鱼肌肉中的主要差异蛋白质,以揭示冷却和热加工对脆肉鲩肌肉特性影响的机制,为脆肉鲩保鲜和深加工提供理论依据。主要研究内容和结果如下：(1)冷冻对脆肉鲩微观结构及质构特性的影响冷冻明显影响脆肉鲩和草鱼肌肉的微观结构和质构特性。冷冻后的肌肉肌束内部形成冰晶,肌束收缩,肌束间隙增大,肌束膜破裂；冷冻导致鱼肉的失重率增大,脆肉鲩的失重率为8.0%-8.5%,草鱼为6.4%-6.8%；脆肉鲩和草鱼肉剪切力、硬度、咀嚼性和弹性分别降低195.06g和467.55g,543.37g和1100.36g,827.28和759.87,0.13和0.20,冷冻对草鱼质地的影响显著大于脆肉鲩的。冷冻使脆肉鲩肌肉肌束膜破裂、肌束破断,从而导致脆肉鲩肌肉脆性下降。(2)热处理对脆肉鲩肌肉结构和质构特性的影响加热温度显著影响脆肉鲩和草鱼肌肉的结构和质地。随着热处理温度的升高,脆肉鲩和草鱼肌肉长度发生收缩,肌纤维束膨胀,肌束间隙增大,肌束膜和肌内膜破裂,肌浆蛋白溶出并填充于间隙中。加热导致脆肉鲩和草鱼肌肉失重率增加、pH值上升,90℃加热10min后脆肉鲩和草鱼肌肉的失重率分别增加17.89%和19.50%,pH值分别上升0.68和0.84。加热鱼肉中可提取肌浆蛋白、肌原纤维蛋白含量和Ca2+-ATPase活性随着热处理温度的升高而降低。随着热处理温度的升高,脆肉鲩和草鱼肌肉的剪切力、硬度、咀嚼性和弹性逐渐降低,且加热对草鱼质地的影响显著大于脆肉鲩。脆肉鲩肌肉质地变化的转折温度为50℃,在50℃-90℃加热其质地变化不大,而草鱼肌肉质地变化的转折温度为50℃-70℃,且其质地随温度升高而急剧下降。(3)热处理对脆肉鲩肌肉风味的影响加热温度对脆肉鲩和草鱼肌肉的气味和滋味有显著影响。经不同温度加热处理的脆肉鲩、草鱼鱼肉的气味和滋味特性有显著差异,且采用不同加热方式(蒸、煮、烤)加工的脆肉鲩(或草鱼)鱼肉的气味和滋味也明显不同。采用电子鼻和电子舌可区分脆肉鲩、草鱼鱼肉以及不同加热方式、加热程度的熟鱼肉样品,且电子舍更为灵敏。SPME-GC-MS分析显示,脆肉鲩鱼肉挥发性成分主要由醇类和醛类化合物组成,且熟鱼肉的挥发性风味成分远高于生鱼肉的。脆肉鲩(生、熟)鱼肉的主体风味成分主要是壬醛、己醛、1-辛烯-3-醇等化合物。(4)热处理对脆肉鲩肌肉持水能力的影响加热温度引起肌肉水分分布状态发生变化。新鲜的肌肉主要以不易流动的水T21存在,随着温度的升高,肌肉中不易流动的水T21逐渐向自由水T22、T23转移。90℃加热10min后脆肉鲩和草鱼肌肉中的T21由最初的95.88%和94.46%分别降至59.42%和79.02%。脆肉鲩肌肉中自由水的含量高于草鱼,其持水能力弱于草鱼。相关性分析表明脆肉鲩肌肉的剪切力和咀嚼性与T21呈正相关,与T22+T23及T2呈负相关。剪切力和咀嚼性与持水性具有极显著的正相关性。(5)热处理对脆肉鲩鱼糜粘弹性的影响加热温度对鱼糜微观结构的影响显著。44-C时,肌纤维和肌纤维束的形状清晰可见,表面开始出现细小的“颗粒”；升温到66℃,纤维膨胀,变得模糊,“颗粒状”的物质增多增大。加热终点90℃,“颗粒状”物质填充于纤维表面和间隙间,且草鱼鱼糜的“颗粒状”溶出物多于脆肉鲩。鱼的种类、含水量、加盐量、升温及降温速率对鱼糜的粘弹性均有明显影响。随着温度升高,鱼糜的弹性模量G’轻微下降,在40℃-45℃迅速下降,而温度高于45℃后鱼糜的G’迅速上升,90℃时达到峰值：冷却时随着温度下降,其G’显著增大；在加热-冷却过程中,脆肉鲩鱼糜的G’显著低于草鱼的。(6)脆肉鲩和草鱼肌肉差异蛋白质组学的研究采用双向电泳对脆肉鲩和草鱼骨骼肌进行蛋白质组学差异的分析,并用质谱技术对差异蛋白进行了鉴定。脆肉鲩和草鱼骨骼肌的2-DE图谱上共发现38个差异蛋白点,脆肉鲩骨骼肌中高表达蛋白点14个,草鱼骨骼肌中高表达蛋白点24个,主要分布在16.7KDa-79.2KDa,等电点pI主要分布在pH4.6-6.4范围。在差异蛋白质组学研究中发现差异蛋白大多属于与肌原纤维结构相关的蛋白质。更多还原

【Abstract】 Crisp grass carp(Ctenopharyngodon idellus C. et V) is commercial fish which is a kind of grass carp (Ctenopharyngodon idellus) fed with broad bean for long time. Crisp grass carp was deeply loved by consumers because its very tight, high viscoelasticity, and delicious taste after cooking. Processing strongly influenced the texture of crisp grass carp muscle. For instance, crispness of muscle increased after cooking at 100℃, and decreased or lost by freezing or high-temperature heating. However, there were few reports about the effect and mechanisms of freezing and heating on physicochemical properties of crisp grass carp muscle. Therefore, the influence on microscopic structure, textural properties, water holding capacity, viscoelasticity, flavor and protein function were studied during freezing and heating using TPA, LF-NMR, SEM, dynamic rheometer, electronic nose and electronic tongue, GC-MS,2-DE and other modern analysis techniques. And the main differential expression protein was analyzed. The aim was to reveale the mechanisms behind the changes in physicochemical properties of crisp grass carp muscle during freezing and heating. This study could provide theoretical basis for crisp grass carp muscle preservation and processing. The main results were as follows:(1) Effects of freezing on the microstructure and texture of crisp grass carp muscleThe microstructure and texture of crisp grass carp and grass carp muscle were significantly affected by freezing. Ice crystal formed inside frozen muscle bundles, and muscle fibers contracted, the distance between fiber bundles gradually increased, and perimysium burst after frozen. The cooking loss of crisp grass carp and grass carp muscle increased after freezing, and were 8.0%-8.5%,6.4%-6.8% respectively. The shear force, hardness, chewiness and elasticity of frozen crisp grass carp and grass carp muscle decreased to 195.06g and 467.55g,543.37g and 1100.36g,827.28 and 759.87,0.13 and 0.20 respectively. The texture of grass carp muscle was more influenced by freezing than that of crisp grass carp. The brittleness of crisp grass carp muscle declined because perimysium burst and fiber bundles broke by freezing.(2) Effects of heating temperature on structure and texture of crisp grass carpThe structure and texture of crisp grass carp and grass carp muscle were significantly affected by heating temperature. As the temperature increased, muscle gradually contracted, muscle fiber bundles expanded, and the distance between fiber bundles gradually increased, and fiber bundle membrane and endomysium broke. Subsequently, plasma protein escaped from muscle cells and filled in the spacing. Additionally, heating resulted in an increase in cooking loss and pH value of fish muscle, cooking loss increased 17.89%,19.50% respectively. In addition, pH value increased 0.68,0.84 when crisp grass carp and grass carp muscle were heated for 10min at 90 ℃. The water-soluble protein and salt-soluble protein content decreased with increasing temperature. As temperature increased, shear force, hardness, chewiness and elasticity of crisp grass carp and grass carp muscle gradually reduced, textural parameters of grass carp muscle changed more than those of crisp grass carp. Textural properties of crisp grass carp muscle was changed at 50℃, and there was no visible change at 50℃-90℃. But textural properties of grass carp muscle was changed at 50℃-70℃, and decreased sharply with the temperature increased.(3) Effect of heating temperature on flavor of crisp grass carp meatFlavor and taste of crisp grass carp and grass carp were influenced obviously by heating temperature. Heating temperature and methods (such as steaming, boiling and baking) significantly influenced flavor and taste of crisp grass carp and grass carp muscle. The electronic nose and electronic tongue could distinguish crisp grass carp and grass carp muscle, and distinguish the heating methods of crisp grass carp and grass carp muscle. And the electronic tongue was more sensitive than electronic nose. The volatile components of crisp grass carp muscle were mainly alcohols and aldehydes by SPME-GC-MS. The volatile flavor components in cooked muscle were more than those of fresh muscle. The main flavour compounds of crisp grass carp muscle (fresh, cooking) were nonyl aldehyde, hexanal, 1-octene-3-alcohol.(4) Effect of heating temperature on water holding capacity of crisp grass carp muscleThe distribution of water in muscle was influenced by heating temperature. The water in fresh muscle was mainly not-easy-flow water (T21), and T21 was transferred into free water T22 and T23. Heating 10min at 90℃ induced the content of T21 decreasing from 95.88% and 94.46% to 59.42% and 79.02% for crisp grass carp and grass carp muscle respectively. Crisp grass carp muscle exhibited higher free water content and lower water holding capacity compared with grass carp muscle. Correlation analysis showed that shear force and chewiness of crisp grass carp muscle were positive correlave with T21, and negative correlation with the T22+T23 and T2. In addition, both shear force and chewiness were significantly positive correlation with water holding capacity.(5) Effect of heating on the viscoelasticity of crisp grass carp surimiThe microstructure of surimi was significantly influenced by heating temperature. Muscle fibers and muscle fiber bundle were clearly visible for raw surimi, and small "particles" began to appear on the surface at 44 ℃. Fibers expanded and blurred, "particles" became bigger and more when temperature further increased to 66 ℃. "Particles" filled in the fibers surface and the fiber spacing at 90℃. "Particles" in grass carp surimi were much more than those in crisp grass carp surimi. The viscoelasticity of surimi was influenced by fish species, moisture content, salt content, heating and cooling rate. The values G’ of surimi slightly declined with increasing temperature, then fell sharply at 40℃-45℃, but increased rapidly when temperature was over 45 ℃, and reached the peak at 90 ℃, and continued to increase remarkably when temperature decreased. G’ of crisp grass carp surimi was significantly lower than that of grass carp surimi during heating-cooling.(6) Studies on skeletal muscle proteomics of crisp grass carp and grass carpThe differences in skeletal muscle proteomics of crisp grass carp and grass carp were studied using two-dimensional electrophoresis, and the different proteins were identified using mass spectrometry. There were 38 different points between crisp grass carp and grass carp muscles,14 high express points in crisp grass carp muscle, and 24 high express points in grass carp muscle. The different proteins mainly distributed in 16.7KDa to 79.2KDa, and isoelectric point in pH 4.6-6.4. It was found that the different proteins in proteomics were mostly associated with muscle fibril structure of protein.更多还原