【作者】 王应强；

【导师】 张慜；

【作者基本信息】 江南大学 ， 食品科学， 2013， 博士

【摘要】 凝胶与胶质类食品的脱水加工提高了其储藏稳定性,形成了具有独特结构与质构以及感官特征的产品。目前,脱水凝胶类食品主要以淀粉基产品为主,加工的主体技术是热风干燥和/或油炸膨化技术或挤压膨化-热风干燥技术,存在脱水时间长、产品含油量高、蛋白含量低等问题。鱼类蛋白含量高,以淡水鱼为主要构成的淡水产品的加工是我国水产品加工最为薄弱的环节,一方面淡水鱼固有的腥味限制了其消费和精深加工,另一方面淡水鱼自身不适的工艺特性以及在这些产品中有限的增值限制了脱水新技术的应用；鱿鱼与海带等海产脱水胶质类食品以盐干和自然干燥为主,加工技术落后,手段粗放,产品质量差,档次低。本论文以鲜有报道的典型凝胶(鱼肌肉和/或木薯淀粉凝胶)以及胶质类水产品(鱿鱼和海带)为研究对象,采用客观仪器分析与主观感官评估相结合的方法,研究了脱水加工对产品结构、脱水过程与品质的影响,分析和探讨了配方与脱水条件在产品结构与相关品质形成中的作用,以期寻找淡水鱼高效加工利用的新途径以及典型凝胶与胶质产品品质改良措施。为了研究脱水鱼肌肉凝胶片的质量,采用热风干燥(AD)、冷冻干燥(FD)、真空干燥(VD)和微波真空干燥(MVD)对白鲢鱼肌肉凝胶片进行脱水并比较了脱水产品的形状、质构、复水特性、复原特性、感官质量与挥发性成分。结果表明,AD、FD、VD引起了白鲢鱼肌肉凝胶片不同程度的干缩而MVD在4、6、8mm厚的凝胶片中引起了膨胀,MVD的产品具有可接受的脆性与愉悦的风味,复水速度快,但复原性差,其硬度、粘着性、咀嚼性与弹性也低；复水凝胶片的感官评分由高到低依次为：FD、VD、AD和MVD的样品；GC-MS分析表明,脱水引起凝胶片中正构醛(n-alkanals)与1-辛烯-3-醇(1-octen-3-ol)含量的显著降低,在MVD的产品中生成了2-甲基-丙醛(2-methyl-propanal)、2-甲基-丁醛(3-methyl-butanal)和糠醛(furfural)。为了理解凝胶类型以及胶凝条件在MVD的凝胶片结构与品质形成中的作用,研究了不同热处理条件下凝胶(鱼肌肉和/或木薯淀粉凝胶)的特性以及MVD的凝胶片的宏微观结构与质量特性。结果表明,高粘弹性的鱼肌肉凝胶和混合凝胶在MVD期间形成了类似淀粉凝胶在油炸过程中形成的膨大多孔结构与质构特性,且最大膨胀的混合凝胶片显示了良好的感官可接受性,在凝胶中蛋白质-蛋白质相互作用是MVD的产品均匀膨化结构形成的控制因素,高的热处理强度促成鱼肌肉凝胶持水力的降低与淀粉的糊化,有利于形成均一结构与高水分流动性的共凝胶体系,从而促进膨化结构与松脆质构的形成。为了理解重组配方在MVD的凝胶片结构与品质形成中的作用,研究了氯化钠、蔗糖、鱼肉与淀粉比例以及淀粉来源对MVD的凝胶片膨胀比、硬度、脆性与感官品质的影响。结果表明,盐溶性鱼肌纤维蛋白是MVD凝胶片膨化结构形成的关键组分,高的氯化钠添加量与鱼肉比例有利于膨化与松脆结构的形成,含有高比例支链淀粉的糯玉米、木薯、土豆淀粉的凝胶比含有小麦与玉米淀粉的显示了更好的膨化特性,所获产品硬度低,脆性高,感官质量好；蔗糖的添加以量效关系抑制凝胶片的膨化,导致凝胶片脆性的降低,但对凝胶片感官质量没有显著的负面影响。最后,基于物料的红外吸收特性,在一套新开发的红外加热对流干燥系统内,研究了风速与红外发射波长对鱿鱼和海带加热与干燥特性以及品质的影响,并与AD和MVD进行了比较。结果表明,在设定干燥介质温度为50℃时,两种物料表面所能达到的恒定温度均高于干燥介质温度,并随风速的增加由52℃增加到63℃,脱水时间随着风速的增大显著越少,而能耗显著增加；2.5-3.0um波长的红外辐射加热干燥比5-6umm的效率高。脱水鱿鱼和海带的品质受风速的影响不显著,而海带的品质呈现出强烈的波长依赖性。与热风干燥相比,红外干燥时间短,能耗低,所获产品与AD的具有可比的质量,好于MVD的产品。更多还原

【Abstract】 Dehydration process for the gel/gelatine aquatic food produces the products with special structure and texture as well as sensory quality while improving their storage stability. Currently, the starch-based products are the most main dehydrated gel food products. The popular technology used is air drying and/or frying expansion or extrusion expansion followed by air drying. The problems related to these products and technologies include long drying time, high-fat and low protein products as well as tedious process. Fish is rich in protein and fresh fish constitutes the most main fresh products, but the processing is the pooreast step in the utilization for the aquatic resources. For one thing, the deodorization inherent in the fresh fish limites its consumption and intensive processing. For anonther thing, both inappropriate processing properties arising from the raw material itselves and limited value added in the fish products restrict the new dehydration technology. Commonly dehydrated gelatine foods such as squid and kelp are produced using salting and natural drying, which are the lagging and extensive method; moreover the resulted products are the low quality and level. With the aim of improving the product quality and enhancing the process efficiency, the thesis studied and discuused the effect of dehydration conditions including (dehydration method, operating parameters and material ingredient) on the dehydration process and the quality of the typical gel (fish muscule and/or starch gel) as well as gelatine product (squid and kelp) using both instrument and sensory evaluation.In order to study the quality of the dehydrated fish muscule gel, the fish muscule gel slices from silver carp were dried using air drying (AD), freeze drying (FD), and vacuum drying (VD) and microwave-vacuum drying (MVD) and quality attributes of the dried products were evaluated in terms of shape, texture, rehydration property, sensory quality and volatile components. The results showed that AD, FD and VD resulted in the different levels of shrinkage while MVD caused some expansion in the4-,5-, and8-mm-thickness samples. MVD products rehydrated faster and had poor restored capacity, low hardness, springiness, cohesiveness aw well as chewiness. MVD products alone exhibited acceptable crispness and favorable odor. The rehydrated dried products were preferred in the order:FD, VD, AD, MVD. GC-MS revealed that drying significantly decreased the n-alkanals and1-octen-3-ol content and produced2-methylpropanal,3-methyl-butanal, and furfural in MVD products.To understand the role of thermal conditions and types of gels in the structure and quality development of MVD products, the property of the gels (tapioca starch gel and/or fish gel) produced under thermal conditions and the quality of MVD gel slices were studied. The results showed that after MVD the fish muscule gel and the mixed gel with good viscoelasticity devolope an expanded and/or porous structure similar to that created by frying in starch gel for which the interaction among proteins was resposible, the mixed gel slices with the higheast expansion showed a good sensory acceptability. The higher severity of thermal treatment favored greater expansion in the mixed gel chips due to developing a homogenous co-gel with a uniform structure and high moisture mobility.To understand the role of formulation in the structure and quality development of MVD products, the effect of salt, sugar, ratio offish meat and starch as well as types of starch on the quality of MVD gel slices were studied. The results showed that salt-soluble myofibrillar protein was the key factor of developed expansion structure in MVD product. Both high content in salt and high ratio in fish favored the expanded and crispy structure. The gel containing a high proportion of amylopectin, such as waxy corn, cassava, potato starch, displayed a more excellent expansion capacity than wheat and corn; the resulting products had a low hardness, high crispness and good sensory quality. Use of sugar inhibited the expansion of the gel slices and reduced their crispness; there was observed no significantly negative effect on sensory quality.Finally, the effect of infrared wavelength and air velocity on drying behavior and product quality of the shredded squid and kelp were studied base on their infrared absorption characteristics in a novel infrared heating forced convection system and compared with AD and MVD. By setting the dry medium temperature of50℃, the constant surface temperature reached is always higher than that of the dry medium and increases from52to63℃with the increase of the air velocity from0to2m/s. The heating and drying at the wavelength of2.5-3.0um is more effective than that at the infrared wavelength of5.0-6.0um. The total drying time significantly decreased while specific energy consumption linearly increased with the air velocity. Air velocity had no significant effect on the quality of the products of both, but the quality of the kelp strongly depended on the wavelength. Compared with AD, the infrared heating and drying took less time and consumption which produced the products similar to AD, but better than MVD ones.更多还原