【作者】 许雯雯；

【导师】 梁新乐； 王丽；

【作者基本信息】 浙江工商大学 ， 食品科学与工程， 2011， 硕士

【摘要】 鲈鱼为常见的经济鱼类之一,‘也是发展海水养殖的品种之一。鲈鱼肉质坚实洁白,不仅营养价值高而且口味鲜美。目前鲈鱼以鲜销为主,但其超市销量大,养殖量在加大,冰鲜的数量也在逐年增加。在冷冻过程中,产品的保水性与品质的优劣密切相关。水分是食品的主要组成部分,是决定食品的物理化学特性、影响食品风味的主要因素。保水性是水产品生产加工的关键之一,在冷冻贮藏、解冻等过程中常会出现因自由水冻结和蛋白质结合水脱离而造成解冻过程中汁液流失,导致营养损失,同时结合水的脱离也会造成蛋白质冷冻变性影响产品品质。多聚磷酸盐是目前应用最广泛的食品品质改良剂之一,以优良的保水功能应用于肉制品和水产品中。本课题以养殖鲈鱼为研究对象,探讨多聚磷酸盐对养殖鲈鱼品质的影响。利用低场核磁共振技术研究样品的水分含量及形态的变化趋势,以T22的积分峰面积值为指标,筛选出最佳保水效果的不同磷酸盐配比,并对不同处理之后的样品中各种形态的水分变化规律进行分析；同时以硬度、弹性、咀嚼性、黏附性、L、a、b为指标,测定0℃冷藏和-18℃冻藏期内多聚磷酸盐对鲈鱼质构、色差的影响,利用电子鼻技术比较不同处理组的鲈鱼风味变化,通过常用的保水方法测定各处理组。以石蜡切片和透射电镜观察磷酸盐对样品组织结构的影响,对多聚磷酸盐的保水机理进行更深一步的探究,为多聚磷酸盐在中国水产品中的加工利用、品质保持等方面提供理论依据。具体研究结果如下：1、以焦磷酸钠、三聚磷酸钠、六偏磷酸钠的添加量作单因素实验,运用响应面分析法对结果进行了分析得出复合磷酸盐的最优配比。焦磷酸钠溶液浓度1.74%、三聚磷酸钠溶液浓度3.03%、六偏磷酸钠溶液浓度0.92%。磷酸盐对鲈鱼保水性的影响大小顺序：焦磷酸钠>三聚磷酸钠>六偏磷酸钠。经响应面分析得到实验因子对响应值的影响函数表达式如下：R=470120.625-6641.039*A-1618.820*B-1517.133*C-9714.985*A*B+6 528.882*A*C-1994.575*B*C-21755.325*A2-12014.298*B2-8247.6 52*C2通过研究磷酸盐对水分迁移的规律,可以知道磷酸盐的作用在T22弛豫时间及T22的积分峰面积上都有了较好地体现,说明复合磷酸盐主要增加的是肌肉中蛋白质结合水的含量,这与后面对其保水性的验证是一致的。2、利用质构仪、色差仪分析了多聚磷酸盐对鲈鱼鱼肉质地、色差的影响,得到未经磷酸盐浸泡的鲈鱼的各项质构、色差参数随着保藏时间的延长变化较大,经多聚磷酸盐处理的样品各项参数变化幅度不大,通过感官评定发现经过多聚磷酸盐处理的样品口感较好,与质构测定结果一致。另外对电子鼻的测定结果进行分析,发现蒸煮后新鲜样、水浸泡、复配磷酸盐溶液浸泡和市售磷酸盐溶液浸泡的四组样品组内差异不大。3、通过对浸泡增重率、解冻损失率、蒸煮损失率及出品率等指标的分析,发现经复配磷酸盐处理的鲈鱼总体保水效果优于其他组。虽然其浸泡增重率并不是最高,但在之后的解冻损失率最低,仅为2.15%。水浸泡组解冻损失率最大,达到9.26%,新鲜鲈鱼冷冻后的解冻损失率达到8.36%,市售复合磷酸盐的解冻损失率为2.19%。蒸煮损失率明显低于新鲜样及水浸泡组,比市售复合磷酸盐组的蒸煮损失也要小。冻藏1个月后,其出品率(91.8%)也达到最大值,高于其他处理组,从而证实了核磁优化得到的磷酸盐配比的可行性。4、利用实体显微镜观察新鲜样、水浸泡、复配磷酸盐溶液浸泡和市售磷酸盐溶液浸泡的养殖鲈鱼组织切片及在-18℃条件下冻藏1个月的组织切片,发现随着冷冻贮藏时间的延长,未经磷酸盐处理的养殖鲈鱼组织中出现了很多大小不一的孔洞,经过磷酸盐处理的养殖鲈鱼质地得到明显改善。通过透射电镜观察-18℃条件下冻藏1个月的未处理鲈鱼及经复配磷酸盐浸泡的鲈鱼组织结构,并与鲜样进行对比。结果发现经复合磷酸盐作用的鱼肉肌肉组织质地比较好,排列比较整齐。未经磷酸盐处理的养殖鲈鱼结构遭到严重的破坏,蛋白质变性更加严重,说明了磷酸盐能在一定程度上改善肌肉的组织结构。更多还原

【Abstract】 Lateolabrax japonicus is one of the common commercial fishes, and also is one of the development of aquaculture species. It has white high nutritional value and taste delicious. It is fresh to be sold, but the amounts of supermarket sales and cultured lateolabrax japonicus are increasing. The numble of chilled fresh lateolabrax japonicus is also growing. In the freezing process, water holding capacity is closely related to the quality of products. Water is a major component of food and the main factor to determine the physical and chemical properties of food and to improve food taste. Water holding capacity is one of the key factors in processing of aquatic products, In frozen storage, thawing and other processes, free water iss freezing and the protein bound water is leaving which causes frozen drip loss during thawing, then leads to nutrient loss, and bound water out of the organization can also cause the denaturation of protein and affect the quality of products. Polyphosphate is one of the most widely food quality improvers and used in meat products and aquatic products with excellent water features.In this paper, polyphosphates was investigated on improving the quality of cultured lateolabrax japonicus which was chosen as the research object. Water content of samples and the trend was studied by using the low-filed magnetic resonance. Using the peak area of T22 as an indicator, the optimal ratio of compound phosphates which had the best water holding capacity was selected and the changes of various forms of water in different treatment samples were analysed. The effects of polyphosphates on the texture, color of samples at 0℃and-18℃were based on the hardness、springiness、chewiness、adhesiveness、L、a、b. The changes of the flavor of different groups were compared by using the electronic nose and the effect of water holding capacity was determined through the general water conservation methods. The impact of polyphospahte on the structure of the samples was observd and the mechanism of polyphosphate was explored by paraffin section method and transmission-type electron microscope (TEM) method in order to provide a theoretical guide for phosphate in the processing、utilization and quality maintenance of aquatic products. The results are as follows:1. The proportions of TSPP, STPP and HMP were optimized by response surface methodology (RSM) which was based on devising single factor experiment. The concentration of sodium pyrophosphate was 1.74%, the concentration of sodium tripolyphosphate was 3.03% and the concentration of sodium hexametaphosphate was 0.92%. The order of the phosphates affecting the water-holding capacity was TSPP>STPP> HMP.Obtained the experimental factor by the response surface analysis, the value as follows:R=470120.625-6641.039*A-1618.820*B-1517.133*C-9714.985*A*B+6 528.882*A*C-1994.575*B*C-21755.325*A2-12014.298*B2-8247.6 52*C2Through the study of the impact on the discipline of moisture migration, it was known that the role of phosphate had a better reflect on the relaxation time of T22 and the integral peak area of T22. Water content was a major increase in muscle soaked in phosphate compound solution. These were consistent with the general water conservation methods.2. The effects of polyphosphates on the texture, color of samples were analyzed by using texture analyzer, color analyzer. The results showed the texture, color parameters of muscle without be soaked in phosphate compound solution had changed greatly with the increase of storage time. However, the parameters of the samples with polyphosphate changed slightly. The result that the samples treated with polyphosphate taste better by sensory evaluation was consistent with the texture result. In addition, the determination of the electronic nose was analyzed and found that the flavor of fresh samples、water immersion samples、compound phosphate samples、commercial phosphate samples were similar after cooking.3. Through the analysis of indicators, such as weight increasing yield、frozen drip loss rate、cooking loss rate、product yield、it was found the water holding capacity of the compound phosphate samples were superior to other groups. Although the yield of weight increasing is not the highest rate, it had the lowest yield of frozen drip loss. It was only 2.15% which was significantly lower than that of the fresh samples and water immersion samples and lower than that of commercial phosphate samples. The frozen drip loss rate of water immersion samples reached a maximum of 9.26%. The fresh samples was 8.36%, while compound phosphate samples was 2.19%. After one month of frozen storage, the product yield of the compound phosphate samples (91.8%) also reached the maximum value, and was higher than the other treatment groups. This confirmed the feasibility of the optimal ratio by using the low-field magnetic resonance.4. Comparing the microstructure of four treatment groups with that of four treatment groups at-18℃storage for 1 month by microscopes, we found that with the increase of storage time, cultured lateolabrax japonicus without polyphosphate had many different sizes of holes. The texture of the groups with polyphosphate had been significantly improved. The changes of tissue structure of cultured lateolabrax japonicus with and without polyphosphate were observed and compared with the fresh cultured lateolabrax japonicus. The results showed the texture of muscle tissue with polyphosphate was better and more orderly arrangement. The tissue structure of cultured lateolabrax japonicus without polyphosphate was severely damaged, protein denaturation was more serious. This results indicated phosphate can improve the tissue structure of the muscle.更多还原