Research On The Key Technology Of Industrial Production Of "Zha Fish"

Grass carp is one of the largest freshwater fish species in China.Processing of the grass carp into "Zha fish" can effectively increase its added value and enhance its economic value.Taken dry grass carp produced under good hygienic condition and rice powder as main material,and taken mixed sugar&salt,chilli powder,red pigment from Monascus,perilla powder,etc.as subsidiary material,the quality differences between the IF(20?)and NF "Zha fish" were studied in the 50 days fermentation,while several indexes such as quantity of main microbes,titratable acid(TA)content,free amino acids(FAA)content,peptides content,volatile base nitrogen(TVB-N)content,peroxide value(POV),and sensory quality were employed to assess the impact.Taken Lactobacillus plantarum(Lp),Pediococcus pentosaceus(Pp),Staphylococcus xylose(Sx),Saccharomyces cerevisiae(Sc)as starter culture,which was mixed with methods of Lp+Sx+Sc,Lp+Pp+Sc,and Sx+Pp+Sc under a ratio of 1:1:1(v/v/v),the harmful bacterial count and biogenic amine(BA)content of "Zha fish" was assayed periodically under different fermentation conditions,and explore the influence of different starter cultures and fermentation conditions on biological safety of“Zha fish".Taken starter cultures dosage,rice flour dosage,fermentation temperature and fermentation time as factors of orthogonal test,and explore the optimum process conditions of“Zha fish”.Results showed that the quantity of beneficial microbes such as Lactobacillus plantarum,Staphylococcus xylosus and Saccharomyces cerevisiae in IF "Zha fish"was significantly higher than that of NF "Zha fish".It was also encouragingly found that IF could reduce the count of harmful microbes such as enterobacteriaceae and pseudomonas to a level of less than 1(log cfu/g)after 20 days,while the same quantitative level for NF appeared in 10 days later.Sensory quality(score),TA content,FAA content,and peptides content in IF "Zha fish" was significantly higher than that of NF "Zha fish"(P<0.05).As for content of TVB-N and POV in IF "Zha fish",they were significantly lower than those in NF "Zha fish"(P<0.05).The quality of inoculated fermented "Zha fish" was much better than that of naturally fermented"Zha fish"(P<0.05).Data obtained in this study suggested that IF with excellent mixed starter cultures could obviously improve the quality of "Zha fish" compared with NF.The results showed that inoculation fermentation(IF)exhibited better antibacterial effects against E.coli,Pseudomonas,and Staphylococcus aureus than that of the natural fermentation(NF)(p<0.01).Among three mixed starter cultures,Lp+Sx+Sc exhibited the best effect on inhibiting the formation of BA(p<0.05).The BA content of 'Zha fish' gradually reduced as the NaCl content increased from 1%,3%to 5%.While with 20%(m/m)KCl substituted for NaCl,it showed better inhibition effect on BA formation than that of samples no KC1 substitution(p<0.05).The suitable content of composited salt was 2.4%NaCL+0.6%KCl.As the fermentation temperature rose 5? every time from 10? to 25 ?,the BA content also increased significantly(p<0.05).From the point of view of BA control and production efficiency,20 0C is a suitable one.As the mixed sugar content increased 1.5%(from 0.5%to 6.5%),the BA content showed a trend of decline.From the point of view of sensory quality and BA control,5.0%mixed sugar was preferred.The BA content showed a fast increasing trend at the first 30 d of fermentation,and the interval of 10 d caused a significant difference(p<0.05),while as the fermentation time prolonged furthermore after 30 d,the BA content decreased significantly(p<0.05).Using Lp+Sx+Sc as starter culture to fermentation for 50 d,the total content of BA in 'Zha fish' was as low as 43.50 mg/Kg,and an excellent sensory quality could be achieved.Orthogonal test was conducted to determine the optimal processing technology of IF fermentation "Zha fish".The optimal processing conditions were as followings:The amount of rice flour added was 40%,the fermentation temperature was 300?,the fermentation time was 30 days,and the starter cultures added was 1.9×108 CFU/g.The influence order(from big to small)of four factors on sensory score and total biogenic amine of the 'Zha fish' was as followings:rice flour added>fermentation time>fermentation temperature>starter cultures added.