Study On Slurry Ice Preservation Of Chub Mackcrel

Chub mackerels (Pneumatophorus japonicus) are usually captured from pelagianfishery. An effective preservation on board is needed to ensure the freshness of the products.Since the application of flake ice and refrigerated sea water has been widely used nowadays,the disadvantages of both disaposal, such as a waste of labour, low cooling efficiency andphysical damage are just what we want to avoid. Slurry ice is a new kind of refrigerant thatbecomes more and more popular in fishery home and aboard for its smaller and smoothershape of ice crystals and both faster chilling rate and higher cooling efficiency. So the studywas taken in order to investigate the effect of slurry ice preservation on chub mackerel. Thedetailed researches were as follows:1) Measurement of the essential nutrients of chubmackerel;2) Study on the effect of slurry ice preservation of chub mackerel in a staticalcondition;3) Research on the role of slurry ice preservation of chub mackerel whensimulating transportation on board;4) Detecting the mechanism of slurry ice preservationon chub mackerel. The main results from the research were as follows:Content of water, total protein, total fat and ash in chub mackerel were investigatedsystematically. The results are as follows: the water content was as high as70.09%, proteincontent was15.7%, and fat content was no less than12.1%, so that chub mackerel can beputrefactive easily.Chub mackerels were immersed in flake ice and slurry ice separately and then storedat-2℃for14days. The effect of both refrigrants was researched during storage. Theresults showed a better control of pH value, TVB-N value, TBA value and lower counts oftotal bacteria when stored in slurry ice. The sensory analysis, as well as the analysis of fleshcolor and odour, showed that the quality of mackerel was better with slurry ice method thanflake ice.Simulating preservation on board, chub mackerels were treated with differentmethods(slurry ice, flake ice and blank control), then stored in a low temperature shakerincubator(-2℃,50rmp/min). Evaluating sensory, chemical and microbiological quality, aswell as changes in flesh texture, it turned out that the effect of slurry ice is the best amongthese methods. Sensory analysis showed that the shelf-life of chub mackerel in slurry icecan be14days longer than in blank control and8days longer than in flake ice. The meanpH values, TVB-N values, TBA values, total bacteria counts of products in slurry ice weresignifficantly lower than any other methods. However, there were no signifficantdifferences in the variation of flesh color and texture. The content of myofibrilla protein, total sulfhydryl content as well as the activity ofCa2+-ATPase showed a signifficantly declining trend with storage time. The decrease inslurry ice methods was slighter than other methods so that we can conclude that thedenaturation of myofibrilla protein in chub mackerel was inhibited by slurry ice treatmentduring storage. The distinction in muscle ultrastructure was due to the level of degradationof collagen. Slurry ice can weaken the degradation. Thus slurry ice was a better method inkeeping the freshness of chub mackerel.