Study On Polyvinyl Alcohol-Based Coating Materials And Its Effect On The Keeping-Fresh Salted Duck Egg By Coating Packaging

China is the largest duck egg consumed country. Salted duck egg as a daily consumed traditional food which has entered into industrialization production age. At present, salted duck egg commonly use the vacuum-packing and high-temperature sterilization processes, which was of complex, low degree of mechanization, high costs. In addition, the discarded packaging after consuming are non-degradable and can pollute the environment. So exploring a new fresh-keeping salted duck egg methods has great significance for simplifying processes, debasing packaging costs, mechanized operations, achieving degradable and energy savings. Coating Packaging method is a development direction of the fresh-keeping salted duck egg packaging in recent years, and its effect mainly depends on the choice and formulation of coating materials and film-forming method; Polyvinyl alcohol (PVA) is commonly used in food packaging due to its easy-to-film and degradation, health and safetycharacteristics; But the high moisture permeability of the film caused by the hydrophilic characteristic of PVA greatly obstacling its utility in food packaging. This paper intends to explore a new coating material for fresh-keeping salted duck egg by useing polyvinyl alcohol as the base material, and combining it with the hydrophobic materials. In addition, the preparation of coating and fresh-keeping packaging materials, performance characteristic of formed film and its effect on keeping-fresh of salted duck egg. The contents of this paper mainly composed by the following three parts:1. Study on the fresh-keeping salted duck egg performance characteristics with PVA-based coating materials by response surface method. The water loss rate of salted duck egg is the objective function to establish a number of mathematical model of secondary, and analysis the interaction of PVA concentration with stearic acid concentration and drying temperature on water loss rate. The result showed that the salted duck egg by coating were stored at room temperature after5months, the water loss rate of the optimal groups which were7.86%is than the control group (no film no packaging) to reduce water loss rate of0.52time; The total bacterial counts of test group which is327cfu/g were below the national standard; The effects order of three factors on water loss rate of salted duck egg is as follows:stearic acid concentration, drying temperature, PVA concentration. Optimization the preservation salted duck egg by polyvinyl alcohol-based coating material:PVA concentration9.99%, stearic acid concentration2.13%, drying temperature25.09℃.2. For exploiting new fresh-keeping material of traditional eggs study on the preparation of fresh-keeping material by coating with PVA-stearic acid of coating by chemic cross-linking and its effects on performance characteristic of formed film. The result showed that the water vapour transmission rate of formed film is22.3g/(m2.24h) by coating with PVA, stearic acid and0.4%(w/vH2O) glutaraldehyde concentration. The water-blocking of formed film is about2.5times more than the PVA and stearic acid of the binary blend film. With cross-linking longer and drying temperaturethe of formed film lower, the water-blocking and water resistance of formed film was improved significantly; The function of barrier to water transmission and water-fasting of formed film could be significantly improved (p<0.05); The antimicrobial of formed film with the increase of glutaraldehyde concentration was significantly increased (p<0.05). Under the optimal conditions of coating-keeping fresh material by PVA:PVA5%, stearic acid2%, time of cross-linking reaction45min. cross-linking agent concentration0.4%.dry temperature of formed film55℃and pH6.2, formed film drying time6h.3. Study its effects of the coating on water loss rate of keeping-fresh salted duck eggs, pH and total number of bacteria of salted eggs by using PVA/stearic acid/glutaradehyde composite coating. The result showed that the water loss rate of test group which was6.65%was more than reduced by15%by PVA and stearic acid binary coating for5months storage; The total bacteria of salted duck eggs by PVA-based coating was410cfu/g for6months, and it was still below the national standard; The final pH of the test and vacuum group were similar with the same of raw materials. So the coating can effectively prevent the salted duck eggs spoilage; In the same storage conditions, the water loss rate of cyan salted eggs was significantly lower than white salted eggs (p>0.05). The keeping-fresh method by PVA/stearic acid/glutaraldehyde composite coating is simple, which is low cost and can be used as an effective method for keeping-fresh salted duck eggs.