Study On Application Of Non-phosphate Additive In Frozen Penaeus Vannamei And Mechanism Of Water-holding

In recent years, maricultured Penaeus vannamei have developed rapidly in China. The main way of taking the fresh or live sale can not adapt to the condition that the yeild of shrimp quickly increase. It is very important to keep the freshness of the maricultured shrimp by frozen storage. However, the freezing and thawing processes have a profound effect on muscle physicochemical characteristic, such as the bonding-type of water withdraw and the mobility of water freeze out. This may lead to loss of water holding capacity, which can result in denaturation of the muscle proteins as well as the nutrient loss. The objectives of this study were to select non-phosphate additives, optimize the water-holding process and explore the mechanism of water retention of Penaeus vannamei, which providing the theory basis for the application of a new water-holding agent to accelerate the industrial applications of phosphate substitutes and ensure the product quality and safety in shrimp processing.The main research contents and conclusions of this paper are as follows:1. Changes of biochemical properties from Penaeus vannamei during -20℃frozen storage with -20℃direct freezing and -80℃ultra rapid-deep-freezing were studied. The thawing loss ratio, Total Volatile Basic Nitrogen (TVB-N), pH value, K value and L value were used to evaluate the quality of shrimp. Results indicated that different freezing rates remarkably influenced on the qualities of Penaeus vannamei during frozen storage. The thawing loss, pH value, TVB-N, K value and L value of Penaeus vannamei, which were processed with deep freezing, to some extent, could be restrained. Base on the synthetic evaluation of the shrimp biochemical characteristics, it can be concluded that increasing the freezing rates will help to maintain the original qualities of Penaeus vannamei.2. This paper was to select non-phosphate additives, optimize the water-holding process by response surface methodology and explore the mechanism of water retention of non-phosphate agents.Based on the single factor experiments, the concentration of sodium chloride is 2.0～ 4.0 g/L, the concentration of trehalose is 2.0～4.0 g/L and the concentration of sodium alginate lysate is 4.0～8.0 g/L.Response surface methodology based on Box-Behnken experimental design was employed to evaluate the interactive effects of three crucial variables including concentration of sodium chloride, trehalose and sodium alginate lysate. Two mathematical models for sensory evaluation and thawing loss rate as functions of the three variables were established. The results showed the concentration of sodium chloride, trehalose and sodium alginate lysate had a remarkable effect on sensory evaluation and thawing loss rate. When the sensory score is the highest, the optimal parameter of non-phosphate additive is that the concentration of sodium chloride is 3.0 g/L, the concentration of trehalose is 3.0 g/L and the concentration of sodium alginate lysate is 6.1 g/L. The predictive sensory score is 9.31. When the thawing loss is the lowest, the optimal parameter of non-phosphate additive is that the concentration of sodium chloride is 3.0 g/L, the concentration of trehalose is 3.0 g/L and the concentration of sodium alginate lysate is 6.4 g/L. The predictive thawing loss rate is 2.68%.Considering the economic benefits and preparation of non-phosphate additive, the concentration of sodium alginate lysate is 6.1 g/L, and the samples are soaked for 40 min. Under these conditions, the sensory score of shrimp is 9.74 and thawing loss rate is 2.84%.Penaeus vannamei processing with non-phosphate additive could significantly improve water-holding capacity and remain frozen product characteristics.3. A safe and effective phosphate alternative was exploited. The product of non-phosphate additive significantly increased the weight of white shrimp and decreased the frozen drip loss. The effect of phosphate alternative preceded polyphosphate compound. The mechanism of non-phosphate additive was presumed as follows: (i) penetrated into shrimp, swelled and expanded the space of myofibrils or fascicles; (ii) combined with protein and prevented myosin frozen denaturation; (iii) adsorbed and retained entrapped water; formed a film and prevented frozen drip loss. (iv) extracted protein from both ends of A-band and H-band and improved the soluble protein content of shrimp.