A Research On Quality Control Of Skipjack Tuna Raw Material Storing And Processing

Tuna class, with English name known as Tuna which belongs to Scombridae,Pereiformes, Osteichthyes, is the general term for fish that are with breastplate (thisrefers to the scales that are obviously enlarged in pectoral region and front lateral line.)There are17species, belonging to5categories of tuna that are commonly seen whichare respectively thunnus category, katsuwonus category, Neothunnus category, Auxiscategory and Sarda category. Biologically speaking, tuna generalized refers toscombridae family, swordfish family and sailfish family which, in total, will be about30different fish species. Among all these species,6species are with relatively highcommercial value which are Bluefin tuna, Masu Tuna, Bigeye tuna, Yellowfin tuna,Albacore tuna and Skipjack tuna[1]. According to FAO (Food and AgricultureOrganization), catching of skipjack and yellowfin are of the top two which is overmillion tons. They are respectively48%and30%of the total global tunacatching.This thesis carries out researches on raw material resource of skipjack tuna,bigeye tuna and yellowfin tuna, assessment on quality control critical points duringthe processing based on the factors that affected skipjack tuna processing which aretemperature, time, processing technique and equipments, and also research on thechanging of odour and volatile substances during the storage of canned tuna in oil.Research results are as follows:Firstly, upon research on raw material sources, it systematically analyzes thedistribution characteristic of heavy metal and histamine in tuna products, by whichdetermined that mercury is a key monitoring point and special attention must be paidto histamine value of raw material.Secondly, upon research on raw material storage time and fish quality variationand recovery during the processing, it points out that the longer the raw material iskept, the worse the quality will be and the lower the recovery. And temperature andtime have big affect on histamine level. The longer the time, higher the temperaturethe faster histamine will grow.Thirdly, upon research on the storage time of canned tuna in oil, its drained weight and water content in the meat tends to be stable from6months. After storing forcertain period, the PH value, histamine, fat and protein do not change. This provesthat the main nutrition facts in the can do not change with time. Analysis to the flavorsof canned tuna with different storage time by electronic nose and GC-MS analyticalmethods shows that volatile substances greatly changed in canned tuna after4years.Ketone components becomes more and fragrant substances such as1-octene-3-alcohol and2-amyl furan become less. This does not happen for canns justproduction and that have been stored for3years. The components and contents ofthese substances changes slower with the time extended.