Sustainable approach for defatted date seed valorization through ultrasonication-based green extraction: A prospective approach for nutraceutical applications

The present study focused on utilizing ultrasound-assisted green extraction to extract the bioactive compounds from defatted date seed powder (DSP) and analyse the effect of ultrasonication on the left-over extraction residue. Under the optimized condition i.e., 90% amplitude, 8 min extraction time, and <125 μm particle size, maximum total phenolic content (TPC) and total flavonoid content (TFC) were 17.44 mg GAE/g and 9.086 mg QE/g; the antioxidant activities were 40.17, 74.22, and 21.61 mmol TE/g for ferric ion reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrlthydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, respectively. Among the three varieties studied (Khalas, Fardh and Khenaizi), Fardh showed the highest TPC, TFC and antioxidant activity. All three varieties comprised of benzoic acid, catechin, vanillin and ferulic acid as major polyphenol. The remaining solid residue after extraction of bioactive compounds was further analysed for different physicochemical properties. Ultrasonication significantly (P < 0.05) affected the particle size, bulk density, colour, and water holding capacity (WHC) of the remaining solid fiber rich residue. Compared to previous studies, the present study demonstrated the efficient extraction of polyphenols using ultrasound-assisted extraction from defatted date seeds. In addition, the findings also showed significant improvements in the physicochemical properties of the residue that resulted after the extraction. Overall, the findings clearly showed that the date seed's bioactive compounds can be efficiently recovered using green and sustainable extraction technologies and could potentially be utilized in food and nutraceutical applications.