Valorization of By-product and Industry Waste for Date Palm Fruit by Recovering Bioactive Molecules and Possible Applications: A Circular Economy Model

Date palm was domesticated between 3000 and 4500 B.C. in Mesopotamia. In 2020, the global production of dates reached 9.45 million metric tons. Date fruit production and the linked processing industry generate a large volume of by-products and waste. The by-products and waste contain valuable amounts of bioactive compounds, but little attention has been given to understanding their chemical composition and properties. The aim of this study was to investigate, by HPLC-DAD-MS and 1 H-NMR analyses, the chemical composition of polysaccharides and polyphenols of by-products and waste from the production process of bioethanol via fermentation of date palm fruits. Cinnamic acids, luteolin, and chrysoeriol derivatives were identified. The total phenolic content in the different samples ranged from 15.6 to 92 mg/g. Two main polysaccharide fractions (F1 and F2) were collected from each sample: F1 and F2 ranged from 4.5% to 9.2% and from 3.5% to 12.5% weight with respect to the date fruit by-products, respectively, and they contained 24–52% and 5.6–8.7% galacturonic acid, respectively. The different compositions of the two polysaccharide fractions were confirmed by the percentage composition of acetic acid and methanol linked to galacturonic acid.