| The purpose of this study was to preserve the fruits and prolong their storage period.First,by improving the mechanical,barrier and thermal properties of the biodegradable PLLA,PLLA/PEG copolymer films with different topologies and pure PLLA were prepared by chemical synthesis method and blending method respectively.The PLLA/PEG blend films were prepared by adding 20%40%PLLA/PEG copolymers respectively.The mechanical properties,thermal properties and barrier properties of PLLA/PEG copolymer film and blend film were tested.On the basis of the respiration characteristics and the gas selective permeability of the blend film,the best fresh-keeping state was obtained and the gas composition,sensory quality and weight loss rate in the bag were measured.With the intercalation of PEG,the yield strength,elongation at break and Young's modulus of PLLA/PEG copolymer films gradually increased to 300%and 200%,respectively.The toughness of PLLA was improved with the addition of PEG.The C02/02 selective transmittance ratio of PLLA/PEG films increased with the increase of the number and content of PEG arms.The CO2/O2 selective transmittance ratios of 4-40%and 8-40%films were 5.76 and 7.08 respectively,which were more favorable for fruit and vegetable packaging..In addition,the crystallization rate of the pure PLLA PLLA/PEG material is also improved obviously.Selection of six kinds of blend Film and Pure PLLA Film with different blending ratio in Fresh-keeping experiment,and the control group was used as the control group without any packaging.The fruit is packed and kept fresh by four weights.The results showed that 4-40%and 8-40%PLLA/PEG films had a freshness preservation period of 36 days.During storage,the sensory quality and weight loss rate of the fruits in the package changed slowly,and the concentration of gas in the package was more suitable for keeping fresh in the atmosphere.Compared with 8-40%PLLA/PEG film,it has the best fresh-keeping effect,and achieves the ideal fresh-keeping effect.. |
PDF Full Text Request