【作者】 张莉莉；

【导师】 薛长湖；

【作者基本信息】 中国海洋大学 ， 食品科学， 2013， 博士

【摘要】 为获得常温流通即食鱼糜制品，本文以狭鳕鱼糜凝胶作为研究对象，研究了高温（100¹20°C）处理对其质构特性、水分状态、凝胶微观结构、蛋白分子聚集态、蛋白质空间结构以及分子间化学作用力等的影响，来阐释凝胶在高温热处理条件下的变化机制。在此基础上，通过调节水分及添加食品大分子化合物来保持或改善鱼糜凝胶的高温处理热稳定性，进一步了解水分及食品大分子化合物对鱼糜凝胶高温处理热稳定性的影响机制，为即食鱼糜制品的研究和生产提供一定的理论依据和技术支持。主要研究内容和结论分述如下：1.采用反压杀菌设备对阿拉斯加鳕鱼糜进行高温处理使其中心温度分别达到100±1°C、105±1°C、110±1°C、115±1°C和120±1°C，并保持10min，测定其质构特性、水分状态、凝胶微观结构以及蛋白质空间结构的变化情况，从而了解鱼糜凝胶在高温处理过程中的变化机制。结果表明，随着高温处理（≥100°C）温度的升高，鱼糜凝胶中最主要的蛋白质二级结构——无规则卷曲发生破坏，导致肌球蛋白重链完全消失，肌动蛋白含量显著下降，蛋白质分子发生聚集，从而使分子间的化学作用力发生变化——离子键和疏水相互作用下降剧烈，而氢键和二硫键整体上呈现上升趋势，另外，鱼糜凝胶的网状结构骨架变得脆弱，孔隙变大，进而降低了鱼糜凝胶的持水性能，导致鱼糜凝胶质构特性的破坏。2.向鱼糜中添加不同保水剂制成溶胶或经加热制成凝胶，经冷风干燥不同时间，测量水分含量、水分活度和水分状态的变化，然后进行高温处理，通过5分法评分标准评定鱼糜溶胶高温处理后的凝胶特性。结果表明，冷风干燥可显著降低鱼糜溶胶及凝胶的水分含量有效提高鱼糜溶胶及凝胶高温处理后的凝胶特性。另外，添加保水剂可改变鱼糜溶胶及凝胶中的水分状态及分布，使其在水分含量大致相同的情况下水分活度显著降低，从而进一步提高鱼糜溶胶的高温处理热稳定性。3.有研究报道，小麦蛋白可显著提高肉糜制品的高温处理热稳定性。本研究将可溶性小麦蛋白（HWG）添加到狭鳕鱼糜中制成凝胶，测定复合凝胶经高温处理后质构特性、水分状态及微观结构等的变化情况，从而了解HWG对鱼糜凝胶高温处理热稳定性的作用机制。结果表明，鱼糜经低温凝胶化过程后加入HWG，可使得肌原纤维蛋白充分交联形成网状结构之后，HWG均匀地分散于其网络结构空隙中，并与周围的肌原纤维蛋白相互作用，形成均匀的凝胶体系，阻碍了肌原纤维蛋白分子在高温条件下的聚集，从而抑制了高温处理对凝胶网状结构的破坏，使得凝胶的持水性及质构特性得到保持或提高，进而使凝胶的高温处理热稳定性得到了很大程度的提高。4.褐藻胶与Ca²⁺可发生反应形成褐藻酸钙凝胶。本研究对其质构特性、持水性及水分状态等进行研究，通过与不同食品胶进行复配之后将质构特性最好的复合胶应用于提高鱼糜凝胶的高温处理热稳定性。结果表明，褐藻胶浓度为4%的褐藻酸钙凝胶的质构特性、持水性等性质都比较好。不同的食品胶对褐藻酸钙凝胶的性质具有一定的影响。其中，魔芋胶对褐藻酸钙凝胶质构特性、微观结构等性质的增强效果最好。褐藻酸钙-魔芋胶复合胶可显著提高鱼糜凝胶的高温处理热稳定性。其对复合凝胶质构特性的增强效果主要是通过增强其破断强度引起的，高温对复合凝胶的凹陷度具有显著的降低作用，因此，高温处理后的复合凝胶脆性比较强。更多还原

【Abstract】 In order to obtain ready-to-eat surimi products circulated at room temperature, AlaskaPollock surimi gels were selected to study the effects of high-temperature (100~120°C)treatment on their textural characteristics, moisture status, microstructure, aggregation ofprotein molecules, protein spatial structure and intermolecular chemical interactions, etc.so as to explain the changing mechanism of the surimi gels with high-temperaturetreatment. On this basis, the thermal stability of the surimi gels with high-temperaturetreatment were maintained or improved by adjusting water or adding macromolecularfood compounds, and further the mechanism how water and macromolecular foodcompounds affected the thermal stability of the surimi gels with high-temperaturetreatment were understood, providing some theoretical basis and technical support for theresearch and production of ready-to-eat surimi products. The main contents andconclusions are as follows,1. Alaska Pollock Surimi gels were obtained by sterilization in counter pressure retortand maintaining their central temperature at100±1°C,105±1°C,110±1°C,115±1°Cand120±1°C for10min respectively. The changes of the textural characteristics,moisture status, microstructure and protein spatial structure were studied to explain thechanging mechanism of surimi gels with high-temperature treatment. With treatingtemperature (≥100°C) increasing, the main protein secondary structure of the surimi gels,random coil damaged, resulting in the disappearance of myosin heavy chain andsignificant decrease of actin content. Protein molecules aggregated and the chemicalinteractions between the molecules changed, ionic bonds and hydrophobic interactionsdecreasing severely, while hydrogen bonds and disulfide bonds taking up an overallupward trend. Moreover, the frames of the network structure became much more fragile and the holes became larger, reducing the water holding capacity of the surimi gels andfurther leading to the destruction of the textural properties of the surimi gels.2. Different water retaining agents were added into surimi sols, some of which weremade into gels by heating. Both of the sols and gels were treated with different period ofcold-drying and the changes of moisture content, water activity and moisture state weremeasured. Then the sols and gels were treated with different high temperatures and the gelproperties were explored by a five-point grading system. Cold-drying significantlyreduced the moisture content of the surimi sols and gels, effectively improving theirtextural characteristics with high-temperature treatment. Moreover, adding water retainingagents changed the status and distribution of the moisture in the surimi sols and gels. Thewater activity was significantly reduced while the moisture content was almost the same,so the thermal stability of the surimi sols and gels with high-temperature treatment wasfurther improved.3. It was reported that wheat protein could significantly improve the thermal stability ofminced meat products. In this study, hydrolysed wheat gluten (HWG) was added andsurimi-HWG plural gels were made. The changes of the textural characteristics, moisturestatus and microstructure of the plural gels were measured to explain the mechanism howHWG affected the thermal stability of the surimi gels with high-temperature treatment.Before the addition of HWG, there was a low-temperature gelation process of surimi, inwhich the myofibrillar proteins sufficiently cross-linked to form a network structure, thenHWG uniformly dispersed in the holes of the network structure and interacted with thesurrounding myofibrillar protein, forming a uniform gel system which inhibited theaggregation of the myofibrillar protein molecule under high temperature conditions,thereby suppressed the destruction of the network structure of the gels withhigh-temperature treatment. So the water holding capacity and textural properties of thegels were maintained, and the thermal stability of the gels with high-temperaturetreatment were further improved.4. Alginate can react with Ca2+to form calcium alginate gel. In this study，the textural characteristics, water holding capacity and moisture status of the gel were studied. Inorder to improve its gel properties, other food gums were added. Then the plural gum withthe best gel properties was applied to improve the thermal stability of surimi gels withhigh-temperature treatment. The results showed that the calcium alginate gel with alginateconcentration4%showed the best gel properties and water holding capacity. Differentfood gums had certain effects on the properties of the calcium alginate gel, among whichkonjac gum had the best enhancement effect on the texture and microstructure of thecalcium alginate gel. Calcium alginate-konjac plural gum significantly improved thethermal stability of the surimi gels with high-temperature treatment. How the plural gumenhanced the gel properties of the gels with high-temperature treatment was mainly byincreasing the breaking strength. High temperature significantly reduced the deformationof the gels. Therefore, the plural gels with high-temperature treatment were brittle.更多还原