Valorisation of unavoidable food supply chain wastes: mango peels, peach peels and pea vines

Traditionally, chemical and allied industries have been reliant on fossil fuels as a feedstock for their chemical, material and energy needs. Simultaneously, global population, resource consumption and waste (global megatrends) continue to increase leading to an unsustainable future if we continue to rely on crude oil as a feedstock for daily needs. As a result, biomass or renewable resources, such as unavoidable food supply chain wastes, represent an interesting opportunity to transition from linear, petroleum-based economies to circular, biobased bioeconomies (cradle to cradle).
Herein, the valorisation of three unavoidable feedstocks, namely: mango peel; pea vines, and; peach peel, is reported. Subcritical water extraction and microwave
extraction were used as novel green techniques and they turned out to be better in both yield and greenness, achieving highest pectin yield of 18.34 % with over 70 % degree of esterification (DE) for mango peel waste, highest pectin yield of 7.47 % (78 % DE) for peach peel waste and highest biopolymer yield of 15.89 % from pea vine waste. Apart from extraction of pectin and microfibrillated cellulose (MFC), hydrothermal liquefaction was studied in mango peel; lye peeling simulation was studied in peach peel; and microwave pyrolysis was studied in pea vine waste. The potential applications of the extracted products were also investigated.
This study provides a green route for the valorisation of food supply chain waste and contributes as a source of biobased materials and chemicals for a sustainable 21st
century.