Application Of Edible Coating In The Preservation Of Pot-Stewed Duck Neck

Sauce and halogen meat products are well received by consumers because of their delicious,nutritious and healthy benefits.The product is susceptible to microbial growth and spoilage,resulting in a very short shelf life.In this study,the microbial composition of different batches of Pot-stewed duck neck was studied by Illumina MiSeq high-throughput sequencing technology.The dominant spoilage bacteria in the end of the rotten duck neck were determined by OTU clustering,Alpha diversity and species classification analysis.On the one hand,for the three natural preservatives of sodium alginate,Nisin and natamycin,the single-factor preservation treatment was carried out to study the quality change of the Pot-stewed duck neck during storage,and the optimal concentration of the three preservatives was selected.Then orthogonal experiments were carried out to further screen the ratio of the best composite fresh-keeping coating liquid.On the other hand,sodium alginate was used as a film-forming agent,and high-pressure shearing and micro-jet high-pressure homogenization were used to prepare lemon essential oil crude emulsion and nanoemulsion edible coating liquid.The physicochemical properties of the two emulsion coating liquids were characterized,and the effect of the essential oil emulsion on the preservation of the refrigerated duck neck was studied.1.The flora structure of duck necks produced in different batches has certain similarity.At the door classification level,it is mainly Proteobacteria and Bacteroides,followed by Actinomycetes and Thick-walled bacteria.At the genus level,the dominant spoilage bacteria were: Pseudomonas,Acinetobacter,Pseudomonas,and Bichiatos.2.The effects of three natural preservatives on the quality of the Pot-stewed duck neck were compared by orthogonal experiment,and the optimal combination of fresh-keeping coating liquid was screened.The preservation effect of the three natural preservatives was better than that of the blank group,among which Nisin showed strong antibacterial effect,and the film formed by sodium alginate had better antioxidation effect.When the concentration ratio of the three natural preservatives is 1.0 g/100 mL sodium alginate,0.9 g/100 mL Nisin,and 0.18 g/100 mL natamycin,the coating liquid has the best preservation effect on the quality of the Pot-stewed duck neck.The total number of colonies,TVB-N,pH,TBARS and color difference at the 15 th day after cold storage at 4 °C were(5.37±0.08)lg(cfu/g),(20.86±0.79)mg/100 g,(5.85±0.06),(2.68±0.079)mg/kg,(1.51±0.07),both were significantly better than the control group(p<0.05),and had no significant effect on the color difference,which could effectively prolong the shelf life of the Pot-stewed duck neck.3.Compared with the crude emulsion,the nanoemulsion coating has the lowest particle size,whiteness index and viscosity,and the appearance is translucent.The quality of the duck neck in the blank group gradually decreased during the cold storage period and was completely spoiled on the 12 th day.The TBARS and TVB-N values were as high as 3.23 mg/kg and 33.6 mg/100 g,respectively,and the colony log value increased to 5.79.Compared with the crude emulsion group and the sodium alginate group,the lemon essential oil nanoemulsion group had the best preservation effect(p<0.05).On the 12 th day,the TBARS and TVB-N values were only 2.71 mg/kg and 20.7 mg/100 g.The colony log value is only 4.85.In addition,there was no significant difference in the color difference between the lemon essential oil emulsion group and the blank group(p>0.05).The results showed that the edible coating of lemon essential oil emulsion can significantly improve the fresh-keeping effect of the Pot-stewed duck neck,and the essential oil nanoemulsion coating has the best preservation effect,and the shelf life of the product can be extended from 8 days to 12 days.