Research And Development Of Preservative Based On Gracilaria Lemaneiformis Oligosaccharides On Fish

Decapterus maruadsi is one of the most important low-valued economic fishs which distributes in the southeast of China.In 2014,decapterus maruadsi’s amount of fishing is only less than that of the trichiurus lepturus and anchovy,ranked the third largest fished marine fish.As an important seafood with high quality,larimichthys crocea’s amount of breed ranked the first of total mariculture fishs in 2014.But decapterus maruadsi is very easy to be spoiled because of its high content of unsaturated fatty acid.The larimichthys crocea is also easy to be spoiled due to its high protein content,high activity enzyme and moisture content in the flesh.Gracilaria lemaneiformis is one of the most important red algae which is mainly used to produce agar in China.But the processing and use of gracilaria lemaneiformis are lack of high value-added products.It has become the primary problem need to be solved to develop the preservative which can effectively delay the spoilage of decapterus maruadsi and larimichthys crocea and extend their shelf life,utilizing the bioactivity such as antioxidant and other properties of gracilaria lemaneiformis.The solution of the problem can also promoting the transformation of gracilaria lemaneiformis’ breeding industry.In view of this,the development of preservative based on gracilaria lemaneiformis oligosaccharides has been carried out in this study.First of all,this study carried out the preservative experiment on decapterus maruadsi and larimichthys crocea using the gracilaria lemaneiformis oligosaccharides obtained from the degradation of gracilaria lemaneiformis by deep-sea bacteria called flammeovirga pacifica at 4 ℃.This part mainly test the freshness indexs as follows: sensory analysis,physical and chemical indexs(pH,K value,total volatile basic nitrogen,histamine,thiobarbituric acid,textures)and microbial index(total viable count).Comprehensive analyzed the influence of gracilaria lemaneiformis oligosaccharides on these freshness indexs during cold storage at 4 ℃.The results shows that the treatment of gracilaria lemaneiformis oligosaccharides can extend 2 days shelf life of decapterus maruadsi compared to the control group during cold storage at 4 ℃.It also shows that the treatment of gracilaria lemaneiformis oligosaccharides can extend 1~4 days shelf life of larimichthys crocea compared to the control group during cold storage at 4 ℃.All these results show that gracilaria lemaneiformis oligosaccharides can inhibit the growth of microorganism and fat oxidation in fish flesh.It demonstrated that the gracilaria lemaneiformis oligosaccharides has preservation activity.Secondly,the development of compounded preservative based on gracilaria lemaneiformis oligosaccharides was carried out.According to the hurdle technology and response surface methodology based on Box-Behnken experimental design.This part optimized the compounded agents base on gracilaria lemaneiformis oligosaccharides.It was demonstrated that gracilaria lemaneiformis oligosaccharides and chitosan had a significant interactive effect.While tea polyphenols and chitosan had an extremely significant interactive effect.According to the comprehensive analysis by Design Expert 8.0.6,the best formulation of compounded preservative is composed by 0.521% of gracilaria lemaneiformis oligosaccharides,0.194% of tea polyphenols and 0.416% of chitosan.And then the indexs was tested as follows: sensory analysis,physical and chemical indexs(pH,K value,TVB-N,histamine,TBA value,textures)and microbial index(total viable count)of decapterus maruadsi and larimichthys crocea to analysis the preservative activity of compounded preservative during cold storage at 4 ℃.The results show that the treatment of oligosaccharides compounded agents can extend 3 days shelf life of decapterus maruadsi compared to the control group during cold storage at 4 ℃.It also shows that the treatment of oligosaccharides compounded agents can prolong 3 to 6 days shelf life of larimichthys crocea compared to the control group during cold storage at 4 ℃.The development of compounded preservative based on gracilaria lemaneiformis oligosaccharides could not only solve the problem that decapterus maruadsi and larimichthys crocea are perishable,ensure the safety of food.But also promote the high valued utilization of gracilaria lemaneiformis,and promote the transformation development of gracilaria lemaneiformis breeding industry.