The Research Of The Effect Of Nanocomposite Packaging Technology On Supermarket Steamed Bread And Dishes

Nanocomposites is a new packaging technology, which will be widely used in food preservation field.In this paper, two types of nanocomposites were developed to make up for the nano-Ag loading material and nano-SiO2 loading material . The new types of material with good antimicrobial properties and stable chemical nature were obtained by mixing nano-Ag with nano-SiO2 in different ratios.First of all, a comprehensive evaluation of the characteristics of nano-composites, including the micro-structure characteristics, physical properties (oxygen permeability rate , water vapor permeability rate), anti-bacterial properties (Gram-positive bacteria, gram-negative bacteria and fungi) and health index (heavy metals, Evaporation residue, detreated stability and migration of nano-silver), were accomplished. The results showed that: Nano-particle size distribution in materials ranging from 40-350nm, and the majority of particle sizes in the 75-100nm; the health index was in line with national standards; when immersing 2h at 60℃, 4% acetic acid solution, silver migration respectively 9.02×10-6mg / L, 8.035×10-6mg/ L, far below the water containing silver limited toxicological indicators; the anti-baicterial test shows that the inhibitory rate of the bacteria was above 90%, and the role of anti-fungal; oxygen permeability of two types of Nanocomposites decreased by 30.5%, 19.2%; water vapor permeability decreased by 18.8%, 8.2%, lower oxygen and water vapor permeability rate will provide a good condition for Spontaneous Controlled Atmosphere.In view of the needs of industrial production of steamed bread, HACCP principle was used to hazard analysis and confirm the critical control points(CCPs). Acceptance of raw materials, acceptance of packaging materials and steaming process must be controlled as CCPs, and critical limit of steaming time was 20min. The first study to verify the effectiveness of nano-composites on preservation of steamed bread was carried out, and the results showed that nanocomposites packaging bread had higher sensory score than the control, and the hardening of steamed bread was significantly slowed down, when the shelf-life of steamed bread extended to 10d, the microbial indicators also meet the health standards .The nano-composites were applied to the preservation of fresh-cut vegetables. Two typical dishes that most consumers rely on (fresh-cut potatoes and water bamboo-chilled meat) were chosen, and the effect of two types of nanocomposites on sensory acceptability, physicochemical indexes and microbiological analysis were evaluated. It showed that two types of nanocomposites can effectively inhibite respiration, decrease weight loss, inhibite PPO activity, decrease the loss of ascorbic acid; two types of nanocomposites can also effectively inhibit bacteria growth, reduce the emergence of volatile basic nitrogen, reduce the weight loss rate of meat juice; they can also significantly reduce water loss of fresh-cut water bamboo and lower MDA content. Therefore, nano-packaging can significantly extend the shelf life of the dishes and improve the quality. By comparing, the effect of type 1 nanocomposites was significantly better than the other nanocomposites on fresh-keeping.