| China is the country with the largest eggs and egg products production in the world, as one of egg products, preserved eggs become an important source of food. With the improvement of people’s living standards, reducing the alkalinity of preserved eggs has become an important aspect of preserved egg production.Therefore, in order to meet the demand of people’s senses, in line with the trend of the people "nutrition", and "health", to reducethe alkalinity of preserved eggs has important theoretical and practical value. In addition, preserved egg production has been from the traditional workshop to a modern scale production, packaging preservation of preserved eggs also become a key factor that affect the quality of the preserved egg flavor.As a result, reducing the alkalinity of the preserved eggs and explore a biodegradable packaging fresh material is of great significance to the energy-efficient, low-carbon emission reduction, green modern automated production paradigm shift in the traditional egg products production.Polyvinyl alcohol (PVA) is easily filming and biodegradable, and is sanitary and safe, so it shows broad prospect in food coating preservation. However, its good hydrophilic property makes the higher vapor permeability of formed film (packaging film), that affects its application in food preservation packaging, optimizing and analyzing the preparation conditions of process and performance. So this project utilize nano-SiO2and nano-CaCO3which to modify PVA on the basis of summarizing forefathers in our laboratory. The modified nano-composite film packaging materials is applied to improve the effect of preserving low alkali preserved egg. The concrete contents and results are as follows1. Research on nano material modified PVA package. The effluence of vapor permeability ad moisture in different nano materials modified PVA packing material determined by single factor experiment. With the response surface test method, studying on modification for PVA with nano-SiO2, nano-TiO2, optimizing this coating material ratio of raw material; establishing a mathematical model, with vapor permeability rate of packaging film as objective function, the amount of nano-SiO2, nano-CaO3as experimental factors; analyzing the effect of various factors and their interactions on vapor permeability rate of packaging film. The result:Adding Nano-SiO2, nano-CaCO3could reduce the vapor permeability rate of this kind of package material effectively. The optimal group decreased by38.04%(P<0.05) compared with the control group. The amount of nano-material had significant interaction with vapor permeability rate of packaging film of PVA and had linear negative correlation.2. Study on marinating low-alkali preserved eggs and preservation of egg which coated nano-modifiecation PVA package material. The production process of the low-alkali preserved eggs was optimized by the response surface which with curing time, salt added quantity, NaOH added quantity for experimental factors, and the best curing process was that marinated25.37d, salt added4.94%, and NaOH add3.63%. Under these conditions, the actual values for each indicator of the low-alkali preserved are:egg whites salt was2.24±0.05%, egg yolks salt was0.69±0.01%, egg white free alkalinity was80.36±1.23mg/100g, and yolk free alkalinity was120.94±2.16mg/100. There were significant interactions(P<0.05) between curing time and salt added quantity and between curing time and NaOH added quantity in the process of the low-alkali preserved eggs. The curing time was negatively correlated with the salt added quantity, and was positively correlated with the NaOH added quantity. In the process of packaging storage, the nano modified PVA coating group (the experimental group) weightlessness rate was lowest, egg white, egg yolk, and free alkalinity were in the relatively stable, the total number of colonies in the preserved eggs after storage for6months was236±7.46cfu/g, Sensory score was significantly higher than the control group with PVA single group. The above conclusions shows that nano modified PVA coating material can significantly improve the preservation effect of PVA. |
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