Fabrication and properties of natural rubber/rice starch/activated carbon biocomposite-based packing foam sheets and their application to shelf life extension of ‘Hom Thong’ banana

Natural rubber (NR) and rice starch (RS) biocomposite-based packing foam sheets were successfully prepared by the Dunlop method, with activated carbon (AC) as a filler to enhance mechanical properties (and to absorb ethylene gas released by packaged bananas). The primary objective of this study was to examine the influences of activated carbon contents from 0 to 20 phr on physical, morphological, mechanical, and thermal properties of the biocomposite foams. With increasing AC content, the foam cell size, density, hardness, compression force deflection (CFD), compression set, tensile strength, elongation at break, tear strength and glass transition temperature (Tg) increased, while the number density of foam cells and rebound resilience decreased. However, the content of activated carbon did not affect the thermal stability. Furthermore, the developed biocomposite foam with 15 phr AC, which had the highest ethylene removal, was used to evaluate the ethylene absorption capacity and the quality of 'Hom Thong' bananas during 12 days of storage in terms of weight loss, pulp firmness, total soluble solids (TSS), physical appearance, and peel color, with comparison to a commercial foam and control. The biocomposite foam with 15 phr AC lowered the ambient ethylene levels considerably, hence delaying fruit ripening and decreasing chlorophyll degradation, TSS, and pulp firmness at 6 days of ambient storage. The proposed biocomposite foam shows potential for enhancing the postharvest storage stability of bananas and has great potential as packaging for other fresh fruit products.