Feasibility study of chitosan extraction from waste leaves of Luffa cylindrica for bioresource recycling

Chitosan as natural, biocompatible and biodegradable biopolymer has been widely considered to own the characteristics of moisturizing, antibacterial and several biological activities for clinical purposes. Chitosan could be obtained from chitins via deacetylation. As known, chitin is typically derived from the exoskeletons crustaceans and fungal cell wall, but this biopolymer can also be found in other sources, such as plants. In fact, Luffa spp. is popularly utilized as Asian edible plants abundant in chitin/chitosan. This first-attempt study tended to reveal chitosan extracted from renewable agricultural waste (i.e., Luffa leaf waste), through comparative analysis upon the contents of the different portions of Luffa. However, studies that discuss the harvest of chitosan from plant sources are rare. Thus, this study explored the most promising strategy to extract chitosan from the waste-Luffa cylindrica leaves. Meanwhile, comparative analysis clearly exhibited the contents of chitosan from different portions of L. cylindrica. The different chitosan-extracting methods would be implemented to obtain the maximal recovery of chitosan. The maximal amount of plant-based chitosan was extracted from L. cylindrica leaves waste through a promising method (i.e., hydrochloric acid under high pressure and high temperature through moist-heating sterilization). Moreover, it was found that the peel of L. cylindrica contained the highest amount of chitosan. Hence, this study showed that L. cylindrica leaves and peel waste would be the most appropriate sources of chitosan. This first-attempt study developed value-added production from edible plant waste for carbon neutrality and circular economy.