The Deepening Study On Process Of Preservation Ice For Prawn

The prawn is consumed because its high nutritional value.However, decaying easily and producing melanin caused by oxidation are seriously affecting its eating quality and nutritional value. The preservation methods used by fishermen nowadays are not up to hygiene standard, which serious effects on the export of Solenocera Melantho.The preservation ice for prawn developed in this study was made by adding preservative and dispersant etc. to water. This kind of preservation ice had beneficial effectiveness on inhibiting blackspots and delaying the speed of decay, controlling the SO2 residue content in spawn was lower than the standard, moreover the price are low. As a consequence of the above, fishermen even more like to use it.In this study, Rosenbergii were collected from local market as sample and investigated the basic nutrients. Preservatives and dispersing agents are compared and screened during the process of preparation, meanwhile, the maximum addition of sodium pyrosulfite are obtained under the condition that the effective components of preservation ice are fully dispersed. In this experiment, dispersion and stability of preservation ice were studied under the condition that Simulated the factories on ice-making. The concentration of sodium pyrosulfite, glycerol and the freezing temperature of ice-making was chosen as the key factor to set up single factor and Response Surface Methodology (RSM) analysises for confirming the best condition of preparation technique of preservation ice for prawn and the distribution of effective components in preservation ice after freezing. In this research, preservation ice was studied for keeping fresh of prawn, the varieties of fresh indicators and concentration of SO2 in each part of prawn body were examined during the progress. The results were as follows:1. The study of comparison and screening of reservatives and dispersing agents showed that sodium pyrosulfite is better than sodium bisulfate and sodium sulfite in the effects of blackspots. Meanwhile, glycerol is better than Sodium Alginate. Carrageenan. Tween-80 and Sodium Carboxymethylcellulose in dispersion effect.2. The suitable addition of sodium pyrosulfite are 600-1000mg/kg under the condition that the effective components of preservation ice were fully dispersed and the safety was ensured. At this concentration the effect of preventing blackspots was the best. 3. Through the single factor experiment and RSM analysis, the optimum process conditions were as followes:sodium pyrosulfite (736.56 mg/kg), glycerol (0.13%) and the freezing temperature of ice-making (-32.9℃). The equation between experimental factors and the response value was as follows:Y= 167.1-0.375Χ1+1.0375Χ2+0.8125Χ3-2.3125Χ12-0.2Χ1Χ2-1.8875Χ1Χ3+0.05Χ22-0.125Χ2Χ3-1.3375Χ324. The distribution of effective components in preservation ice is:(1) The horizontal direction effective component distributed equation may indicate approximately is:Y=-2.16 M2+890.21(2)The vertical direction effective component distributed equation may indicate approximately is:Z= 18.76 N2+657.455. The results show that preservation ice for prawn had beneficial effectiveness on inhibiting blackspots and growth and propagation of bacteria, decreasing bacteria survival number, prolonging shelf life of prawn. Using preservation ice also can controlling the SO2 residue content in spawn, which was lower than the standard.