Extraction of phenolic compounds from pineapple peel using natural deep eutectic solvent (nades)

Agricultural biomass particularly pineapple wastes are among the highest waste produced in Malaysia and the report on the valorisation of the wastes is still scarce. The processing waste from pineapple processing constitutes 50% of the total fruit which largely includes peel, core, trimmings, shreds, crown and leaves. These wastes are rich sources of biomolecules of commercial interest such as phenolic and flavonoid compounds which are advantageous to human health due to their broad-spectrum biological activities. Throughout the years, conventional methods were used to carry out the extraction of biomolecules from plants which employ a variety of organic solvents that are mostly volatile, toxic, and flammable leading to several human risk, safety issues and environmental problems. Mulling over all these, the exploration of natural deep eutectic solvent (NADES) compatibility as green solvents for phytochemical extraction is expected to address the raised issues brought about by the conventional methods. In this study, a newly approach on the green chemistry method of extraction using NADES will be performed for the first time on pineapple wastes. The potentiality of various NADES was screened in determining the best combination of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) in extracting the phenolic compounds from pineapple peels. Results have shown that the highest extraction yield of phenolic compound was obtained from the combination of choline chloride and ascorbic acid at 1:2 molar ratios. It is hoped that through this research, the method of green chemistry can be further explored in replacement of the use of organic solvent in an attempt to extract the potential of active constituents that may add value to the biomass particularly from pineapple wastes.