Study On Freshness Colorimetric Indicates Cards Of Characterized Gas By CO₂

Food freshness indicates cards utilized the color reaction and temperature activated biological reaction that some characteristic of gas reaction with specific reagents in the storage process of food, and the changes of indicates cards caused by enzyme, thus made the judgment of food. In this paper, characterized by CO2 gas, to achieve the optimal ratio of freshness colorimetric indicates cards, we optimized the indicator solution formulation, and taking PL A as the basement membrane material. We studied the properties determination and the influence factors of indicates cards, furthermore, studied on the application of indicates cards, to determine the indication range of indicates cards.We optimized the process of production for PLA films, the final conditions was:The PLA sample with a particle size of lmm was dissolved in chloroform liquid under 3% concentration, and sealed with double wrap, heated among the water bath at 40 ℃ in 30 min until PLA was dissolved completely, laying of PLA films on casting, make of PLA films finally.Determine the pH when the color of indicator solution sudden changed, optimizing the formulation of indicator solution, to finalize the optimum formulation of indicator solution. Add polyethylene glycol-400 with O.O1mL and methyl cellulose with 0.04 g and indicator solution with 3 mL among 100 mL of distilled water, under the 32.1 percent of the CO2 concentration in the package, that indicates cards appeared the most obvious change of color.We observed the microstructure of indicates card through SEM, the picture showed that the surface of indicates coating formed a number of cluster structure, there are a lot of holes in the bottom. Thermal stability, TGA, hygroscopic, transparency were measured for indicates cards, and the results showed that indicates cards was not suitable for heating food with food, dissolution phenomenon of indicates cards appeared indicates under high relative humidity conditions. By changing the time, humidity, temperature and other environmental conditions, the results showed that:the temperature had no significant effect on the discoloration of indicates cards, when the relative humidity was below 50%, indicates cards was most accurate.The practical application of experimental of indicates cards select cake and steamed bread as the sample, add a desiccant to optimize ambient conditions of indicates cards; CO2 concentration in the package, value of chromatism, the total number of colonies for food was measured, an indication of the effect of indicates cards pursue in-depth research, the results showed that the total number of colonies in food up front in line with national standards when indicates cards showing yellow-green, and when the indicator card was beginning to show yellow color, the packaging of food has begun to corruption.