Antioxidant mechanism of a continuous microenvironment regulation system for prolonging the shelf-life of red grapes.

Red grapes (Vitis vinifera L.) have a high sugar content, thin skins, and relatively short shelf-life after harvesting. We developed polylactic acid/polybutylene succinate film, prepared by extrusion of polylactic acid and polybutylene succinate, that significantly prolonged the shelf-life of red grapes from 8 to 12 days by delaying the loss of weight, loss of hardness, and reduction in soluble solid content after harvesting. Further mechanistic study showed that this modified atmosphere film delayed the senescence of harvested red grape, the phenomenon that was highly related to the lower active oxygen species production and higher antioxidant enzyme activity compared to the non-packaged grape. The proposed continuous and dynamic microenvironment regulation system is a promising method to study the mechanisms of respiratory metabolism in fruit and extends food shelf-life while reducing food waste. PRACTICAL APPLICATION: In this study, we designed a means to microenvironmental regulatory packaging that directly creates a continuous, dynamic, and monitorable microenvironment. To ensure that the fruit inside the package underwent coordinated aerobic and anaerobic respiration, we melt-extruded polylactic acid (PLA) and polybutylene succinate (PBS) to form a homogeneous biodegradable film. We demonstrated that the best preservation results were achieved with a film comprising an 80/20 PLA-to-PBS ratio. This film can prolong the shelf-life of fruits by regulating respiratory metabolism.

Controlled moisture permeability of thermoplastic starch/polylactic acid/poly butylene adipate-co-terephthalate film for the autolysis of straw mushroom Volvariella volvacea.

Straw mushrooms are prone to autolyze, leading to a high requirement of environmental humidity. In this work, thermoplastic starch/polylactic acid/poly (butylene adipate-co-terephthalate) (TPS/PLA/PBAT) film was produced by extrusion. The moisture permeability of the film was controlled by adjusting the content of TPS, which could be expected to further control humidity of the microenvironment in the package. Results revealed that the water vapor transmission rate of the film linearly increased from 612.31 g/m2·24 h to 1082.50 g/m2·24 h with the increase in the TPS concentration. The TPS/PLA/PBAT film with 30 wt% TPS showed the strongest inhibition on the autolysis of straw mushrooms compared with other groups, effectively delaying the increase in the free water, soluble solid content, rate of weight loss, and polyphenol oxidase of straw mushrooms and extending the shelf life of straw mushrooms from 24 h to 72 h.

Characterization of PLA-P3,4HB active film incorporated with essential oil: Application in peach preservation.

This study aimed to develop an active film by using biodegradable materials and antioxidant essential oils to improve gas and water vapor permeability during peach preservation. O2 and CO2 volume fractions and water status were investigated by using an oxygen meter and conducting low-field nuclear magnetic resonance (LF-NMR), respectively. Results revealed that the film added with angelica essential oil (AEO) had a 49.4% increase in 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity and high O2 and CO2 transmission rates and water vapor permeability. The film added with AEO showed the best preservation effect, effectively delaying the oxidation of peach, maintained the combined water, and extended the shelf life of peaches to more than 15 days. This study provided a relatively new LF-NMR method for tracking the internal water status of packaged peaches and served as an effective reference for the development of active food packaging.