| Eggs are nourishing food. But the production of eggs is seasonal.Lots of fresh eggs are supplied and sold at bargain sales on season,however,there are few eggs off season. So exploring a new fresh-keeping fresh 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 egg packaging in recent years, and its effect mainly depends on the choice and formulation of coating materials and film-forming method; Chitosan is commonly used in food packaging due to its easy-to-film and degradation, health and safety characteristics; But the high moisture permeability of the film caused by the hydrophilic characteristic of chitosan greatly obstacling its utility in food packaging. This paper intends to explore a new coating material for fresh-keeping egg by useing chitosan 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 egg. The contents of this paper mainly composed by the following three parts:1. Eggs were subjected to coating treatment with chitosan/nano-sized SiOx,chitosan and were subsequently stored for 30 d at 28℃and 80% relative humidity. The effect of such treatments on the interior quality and consumer perception of eggs were studied. Results showed that after 28 day storage, the indexes in chitosan/nano-sized SiOx coated eggs were significantly better than those in uncoated ones and slightly better than those in chitosan coated ones, chitosan/nano-sized SiOx coating results in significantly prolonged shelf life as well as good interior quality and consumer acceptability, thereby having a promising potential as a coating agent used for the preservation of eggs.2.For exploiting new fresh-keeping material of eggs study on the preparation of fresh-keeping material by coating with chitosan, nano-sized SiOx and monoglycerides and its effects on performance characteristic of formed film. The result showed that fresh-keeping material by coating with chitosan nano-sized SiOx and monoglycerides can reduce effectively lugeon value and enhance antibacterial property. With chitosan concentration and nano-sized SiOx concentration of formed film increase, 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 chitosan concentration and nano-sized SiOx concentration was significantly increased (p<0.05). Under the optimal conditions of coating-keeping fresh material by Chitosan: chitosan 3%, nano-sized SiOx 2%, monoglycerides 0.1%. dry temperature of formed film 75℃.3. Study its effects of the coating on water loss rate of keeping-fresh eggs, The Haugh unit of egg and total number of bacteria of eggs by using chitosan/nano-sized SiOx composite coating. The result showed that the water loss rate of test group was 2.44% for 1 months; The total bacteria of eggs by chitosan-based coating was 695cfu/g for 1 months;however, the total bacteria of eggs by control group was 1290cfu/g for 20 days; the total bacteria of eggs by keeping in cold storage was 1142cfu/g for 25 days. The Haugh unit of the test was more than reduced by eggs in a low temperature for 1 months storage; The Haugh unit of control group decrease to 19.89 for 10 days. So the coating can effectively prevent the eggs spoilage. The keeping-fresh method by chitosan/nano-sized SiOx composite coating is simple, which is low cost and can be used as an effective method for keeping-fresh eggs. |
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