Pomelo (<i>Citrus maxima</i>) Peel-Inspired Property for Development of Eco-Friendly Loose-Fill Foam

Abstract

For development of eco-friendly packaging foam from pomelo peel, physical and mechanical properties of the pomelo peel and effects of pomelo varieties, namely Kao-Nampueng, Thong-Dee, and Kao-Pan, on their properties were investigated. It was found that the pomelo variety showed somewhat significant effect on physical and mechanical of pomelo peel properties. Because of its thick peel with high moisture content (75-80%) and water activity (0.90-0.98), the peel weight accounted for almost half of the total fruit weight. Cell structure and pore size of the peel were examined using the environmental scanning electron microscope (ESEM). The result showed an open cell foam structure with pore size of approximately 151±31 µm. The pore size was more open and large towards the outer surface. Uniaxial compression tests on pomelo peel samples with and without flavedo showed good reproducible stress-strain curves despite its biological variation. Young’s moduli of both samples were calculated to be 200-300 kPa and 110-210 kPa, respectively. Moreover, the most important property of packaging foam is the ability to absorb energy during impact which can be characterised through the measurement of the onset strain of densification. It was found that the strain values at the maximum energy absorption efficiency (εcd) of peel samples with and without flavedo for all studied pomelo varieties were comparable and were approximately in the range of 60-65%. These preliminary results indicate very promising mechanical properties of pomelo peel as eco-friendly packaging foam although further modifications are required to improve their physical and shelf-stability properties.