Study On The Preservation Effect Of Acidic Electrolyzedwater For Solenocera Crassicornis

Solenocera crassicornis is one of the main marine shrimps in China. It is welcome and popular at home and abroad market due to its springiness, good taste and nutrition. Shrimp have become the main aquatic products processed and export aquatic prioducts in our country, and its economic and social benefits are significant. However, on one hand, its living sea has plenty of microbes, so its initial total viable counts are large, and it’s more likely to be rotten. On the other hand, the shrimp is proned to decay for its high water content, rich in protein, tender muscle as well as active autolysis enzyme. It is difficult to process and storage of shrimp and its products. Therefore, shrimp preservation has always been a research hot spot. To find the way to keep shrimps’ freshness and high quality during long distance transportation and storage is of great research significance.In view of the above-mentioned facts, Solenocera crassicornis were collected from local market, the nutritional composition in the muscle of Solenocera crassicornis was comprehensively analyzed and evaluated, and compared with parapenaeopsis hardwickii and penaeus japonicus. Total viable counts (TVC), pH value, total volatile basic nitrogen (TVB-N), K value and sensory evaluation were used as freshness indicators, and the influence on the quality of Solenocera crassicornis after the sterilization of the acidic electrolyzed water, chlorine dioxide and ozonated water were studied. In order to optimize acidic electrolyzed water sterilization technology of Solenocera crassicornis, the influence of pH, solid-liquid ratio and dipping time on sterilization and sensory evaluation by adopting quadratic regression orthogonal rotation combination design method based on single factor experiment were studied. At last, high-throughput sequencing technology was applied to study the bacterial species and amount changes in the Solenocera crassicornis during the storage with the aim to offer theoretical recommendation. The experimental results were as follow:1. Nutritional components in the muscle of Solenocera crassicornis, was comprehensively analyzed and evaluated. The result showed that the contents of flesh, water, crude ash, crude protein and fat in Solenocera crassicornis were52.00%,80.38%,16.08%,1.28%and1.60%respectively.In dry samples, the content of total amino acids (TAA) was78.39%. The essential amino acids index (EAAI) was82.39, which was ideal source of proteins for human.18kinds of fatty acids were detected in this shrimp. The content (of total fatty acid) of unsaturated fatty acids was58.11%, in which the content of EPA and DHA were26.53%. The ratios of ω-6/ω-3PUFA of Solenocera crassicornis was0.85. In addition, the muscle of Solenocera crassicornis contained abundant macro elements and micro elements. However, the certain hazardous substances of Solenocera crassicornis were lower than standard. Therefore, the nutritional quality of Solenocera crassicornis is higher.2. The Solenocera crassicornis were firstly treated with acidic electrolyzed water, chlorine dioxide and ozonated water, then keeping them at4℃.The preserving effect of three preservation methods were compared by sensory evaluation, total viable counts (TVC), total volatile basic nitrogen (TVB-N), K value, pH as freshness indicators during the storage. The result showed that acidic electrolyzed water significantly inhibited the growth of the total viable counts. It also slowed down the rise of TVB-N, K value, and maintained better sensory quality compared with chlorine dioxide, ozonated water and control. The acidic electrolyzed water could extend the shelf-life of Solenocera crassicornis for2days compared with the control, and prolonged to7days. However, the effects of chlorine dioxide and ozonated water were inferior. They could extend the shelf-life of Solenocera crassicornis for1day compared with the control. Therefore, acidic electrolyzed water prewashing may be a promising method of maintaining the storage quality of Solenocera crassicornis and extending shrimp shelf-life during4℃storage.3. The technological conditions for sterilization of Solenocera crassicornis by acidic electrolyzed water technology were investigated. The influence of pH, solid-liquid ratio and dipping time on sterilization and sensory evaluation by adopting quadratic regression orthogonal rotation combination design method based on single factor experiment was optimized. The results showed that the optimum sterilization technique parameters were as follows:pH value3.40, solid-liquid ratio1:4(w/v) and dipping time to13minutes. Under optimum conditions, the sensory evaluation of Solenocera crassicornis was21.50, and the killing logarithm value of Solenocera crassicornis was1.22log10CFU/g.The function expressions were also obtained as follows through the method of response surface analysis experiment:Y1=20.94-1.08X1-0.88X2-0.23X3-0.50X1X2+0.62X2X30.86X12-0.44X22-1.30X32Y2=1.12+0.037X1-0.009383X2-0.030X3-0.010X1X2-0.014X1X3-0.014X12+0.011X22+0.015X324. High-throughput sequencing technology was applied to analyze the change of bacterial composition and amount during storage of Solenocera crassicornis. The results showed that, the dominant putrefying bacteria of Solenocera crassicornis were Psychrobacter, Pseudomonas, Flavobacterium, Pseudoalteromonas, Chryseobacterium, Carnobacterium and Shewanella during storage (4℃). The acidic electrolyzed water could inhibit Shewanella, Vagococcus, Pseudomonas, uncultured-Aeromonadaceae and Pseudoalteromonas, acidic electrolyzed water could extend the shelf life of Solenocera crassicornis by inhibiting the growth and reproduction of the dominant putrefying bacteria during refrigerated time.