Designing a Diffusion Membrane System for Modified Atmosphere Storage of Fruit and Vegetables at Pallet Scale. The case of Bell Pepper

Abstract

Industrial shipment of horticultural crops needs a cheaper alternative to controlled atmosphere reefer containers for transportation from Europe to markets of America or Asia. The diffusion membrane system patented by Marcellin thirty years ago has been recently developed in France. In this work the design of a model for packaging low quantity of products, and the extrapolation of results to pallets or bins scale has been restudied. Essentially, at chilling storage temperature the O2 and CO2 diffusion through the silicone membrane interacts with respiratory activity of the product within the sealed pack, to allow to an optimum equilibrium atmosphere. The size of a membrane of known O2 and CO2 permeabilities, able to generate and stabilise recommended atmospheres was calculated. Finally, packages made of an impermeable polymeric sheet with a silicone diffusion window of 1 and 1.5 dm2 were applied on 5 kg of ‘Cornabo’ peppers for 21 days at 8ºC, to generate about 5-6%O2 and 4-5%CO2 at the steady sate. Results were compared to air atmosphere at 95% RH. Cold storage was followed by a shelf life of 4 days at 15ºC and 60-70% RH. The gas composition changes within packages, sensorial quality, decay and disorders were monitored. After storage with 1 dm2 membrane the desired atmosphere was achieved, although no equilibrium was reached. However with 1.5 dm2, gas composition equilibrated at about 7%O2 and 4%CO2, being adequate for design purposes. Slightly better sensorial quality and lower decay, without disorders, in modified atmospheres packaged than in control peppers were found. Key words: Packaging design, silicone membrane,