Preparation of modified atmosphere and moisture packaging membranes by blending quaternized polyether ether ketone with polyvinylidene fluoride and its application in grape packaging

The modified atmosphere and moisture packaging membranes for preserving Vitis vinifera L. (V. vinifera) were developed by blending triethylamine-grafted quaternized polyether ether ketone (QPEEK) and polyvinylidene fluoride (PVDF) using thermally induced phase separation. With the addition of QPEEK, the blend membranes exhibited increased hydrophilicity, gas transmission rate, and gas permeability coefficient. For the 5 % QPEEK/PVDF membrane, the water vapor transmission rate is 48.4 g/(m²·24 h), the water contact angle is 82.2°, and the CO₂/O₂ separation coefficient is 2.06. Compared to other groups, this membrane exhibits better tensile, swelling, and relaxation properties. These properties facilitate achieving dynamic air equilibrium within 3 days, maintaining a suitable atmosphere inside the package (3.4–4.1 % CO₂ and 16.1–18.1 % O₂), and timely removing moisture to prevent water vapor condensation, thus extending the shelf life of grapes to more than 25 days. Grapes packaged in 5 % QPEEK/PVDF membrane box maintained 99.3 % mass, 85.1 % firmness, and 72.2 % total phenol content, and exhibited minimal changes in soluble solids, relative electrical conductivity, and water state and distribution compared to fresh grapes. These experimental results suggest significant potential for the use of QPEEK/PVDF membranes in fruit and vegetable packaging.