| On the Basis of present situation of aquaculture and processing of prawn (penaeus vannamei) in our country, effects of major factors before and after capture on browning and preservation were studied in this paper. Three main parts were included here:Firstly, Effect of withholding food methods before capture on quality and browning of prawn; Secondly, Effect of different temperatures on freshness of prawn during storage; Thirdly, Effect of different treatments on freshness and browning of prawn.Results were listed below:1. Effects of food withheld with 0,1,2 days on quality and browning of prawn after capture were measured. The results indicated that withholding food treatments decreased the contents of fat and protein and the metabolism of prawn was mainly digested by fat during early non-feeding stage. Food withheld with 1 day contributed to enhancing survival of prawn under aerobic conditions, effectively reduced the initial number of bacteria, alleviate browning and rotting development of prawn after capture, however food withheld with 2 day easily decreased the quality of prawn.2. To investigate the effects of different temperatures on freshness of prawn, changes of physical, chemical, microbial and sensory evaluation indexes of prawn were measured at different storage temperature (0℃,5℃and 10℃). Data showed that higher storage temperature, the faster propagation of bacteria and the quicker increase in TVBN content and K value. Low temperature storage maintained quality and freshness of prawn, and extended storage life. The optimal storage life of prawn was 6,4 and 2 days respectively, when stored at 0,5 and 10℃. However, the browning of prawn could not be prevented by low temperatures, and other methods must be used.3. Effects of different treatments on freshness and browning of prawn were investigated under conditions of sodium bisulfite soaking and chlorine dioxide soaking as well as chlorine dioxide releasing way, and distilled water soaking was the control. The results indicated that the browning of prawn was effectively inhibited by sodium bisulfite solutions soaking, however because of the concerns for food safety, sulfite was restricted to humans. Chlorine dioxide soaking way could effectively kill microbe, but quickly lost the effort after 2 days. Chlorine dioxide releasing storage delayed markedly the browning, maintained the quality and freshness of prawn after 8 days, and extended the storage life over 2 to 3 days compared to the control. |
