Study On The Fresh-keeping Effect Of Soluble Soybean Polysaccharides Coating On Eggs

As one of the most important livestock products, hen eggs are popular subsidiary food for Chinese people. With the improvement of the safety requirements, people are not satisfied to buy eggs from traditional market. They prefer to buy"clean eggs"from supermarket. The so called"clean eggs", which means that fresh eggs been washed, disinfected, dried, graded, and then coated with fresh-keeping film before sent to supermarket, have a core technology of using fresh-keeping materials.At present, although there are various fresh-keeping coating materials consist of the market, few of them can actually fill the real need of the production of clean eggs. Conventional coating materials are animal fat or chemical reagent, which not only underperform at the fresh-keeping effect, but also are harmful to consumers. Edible and effective coating materials are needed for domestic clean-egg industry, which shall be used widely.In this study, the extraction of Soluble Soybean Polysaccharides (SSPS) from soybean residues was optimized. Then the purified SSPS was employed as the main material combined with plasticizer glycerin and intensifier CaCl2 to develop a newly fresh-keeping coating on eggs. It turned out that the fresh-keeping coating not only can reduce the bacteria delivery of the egg shells, but also can keep the egg's quality at a high level for a long time, and can extend the eggs'shelf life. The specific research results are as follows:(1) The extraction technology of SSPS from fresh soybean residues was optimized. Based on the traditional extraction technology, this new technology omitted the steps of drying, comminution, homogeneity, and the extraction percentage was 33.5%;(2) SSPS is a new fresh-keeping material. SSPS was employed as the main material while as glycerin was employed as plasticizer, CaCl2 was intensifier to develop the new fresh-keeping coating. When the consistence of SSPS, glycerin and CaCl2 was 6.0%, 3.0% and 1.0% respectively, the coating had feasible Water Vapor Permeability as well as the Oxygen Permeability;(3) The SSPS fresh-keeping coating can extend the shelf life of eggs evidently. During the high temperature and high humidity storage period, the Haugh unit and the Yolk index of the SSPS coating eggs were lower than the control group and chitosan coating group and paraffine coating group evidently. After 45 days storage, the quality level of the SSPS coating eggs was AA. Meanwhile, the control group eggs were rancid after 30 days storage, and at 25 days and 30 days, the quality of eggs from chitosan coating group and paraffine coating group were B grade;(4) The SSPS coating's bacteriostatic ability was effective. After one day's storage, the eggs coated with SSPS coating had the strikingly lower total numbers of colony than the control group and chisoan coating group, while as the paraffine coating had no significant difference with control group.