| The quantity of prawn head waste (PHW) is increasing through processing year after yearand there had no good methods of utilizing it effectively at present in domestic shrimpprocessing enterprises. The utilization value of small pelagic species promoted hardly.It is wellknown that the concentration of salt was higher in commecial traditional fish sauce and itsfermentation period was longer which led to fishy, amine flavor or rotten smell of the finalproduct. The research was done according to the present situation. The accelerated fermentationtechnology and physical and chemical properties were studied for low salt fish sauce frommackeral (decapterus maruadsi) mixed with PHW and koji. The result of this research showedthat addition of PHW and koji during the fish sauce processing could shorten the fermentationperiod and improve the flavor of fish sauce through increasing the content of umami and sweetyamino acids. The main points of this research are as follows.First, the research investigated the effect of PHW on fish sauce production using mackeralat30°C incubation, and used the protamex as a comparison. The result of SDS-PAGE showedthat the endogenous protease of PHW could degrade the muscular proteins of mackeral fromdecapterus maruadsi. The total nitrogen and amino nitrogen content were2.03±0.03g/100mLand1.44±0.03g/100mL, respectively at the end of80days fermentation, and total free aminoacids was9.69g/100mL. There were some bitter oligopeptides in the product on the analysis offlavor amino acid composition by this rapid fermentation technology which was partly consistentwith the results of sensory test, yet the evaluation was not bad.Next, the research investigated the influence of addition of koji at the range of20~40°Crespectively. The results showed that the enzyme activity of koji at20°C was higher than othergroups which could shorten the fermentation period and improve the flavor. The total nitrogen,amino nitrogen and free amino acid content were1.71g/100mL,1.42g/100mL and9.20g/100mL, respectively at the end of90days of fermentation, and the salt concentration of thefinal product was12%. Incubated at30°C could not inhibit the spoilage organisms, the qualityof fish sauce was not good followed with the pH increased. The color of the product incubated at40°C was deep dued to Maillard reaction and had unpleasant flavor for the oxidation of lowmolecular unsaturated fatty acids.Thirdly, the research also investigated the effect of mashes and salt content on the fish sauce processing based on the fermented technology of adding the PHW and koji. The results showedthe enzyme activity of koji were lower compared with commerical koji whose mashes werebarley, rice and buckwheat respectively. However this koji could reduced salt content byreducing the pH of fermented liquor and inhibitting bacteria growth. The study on salt contentindicated that the groups of10%salt concentration were better than15%groups, however,10%salt concentration could not inhibit the spoilage organisms. Under10%salt content andbuckwheat as mash was a optimal condition, and the total nitrogen and amino nitrogen contentwere1.62g/100mL,1.31g/100mL, respectively at the end of90days of fermentation.Finally, the paper study the fish sauce fermented under20~30°C and20~30~40°Crespectively. The results showed that20~30°C fermented could enhance the total nitrogen andamino nitrogen content. This rapid fermentation led to high proportion of umami and sweetyamino acids in the product based on the analysis of free amino acid composition. The result ofsense score suggested that fermentation technology had better acceptability of flavor. |
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