Study on the physical, chemical, structural, and functional characteristics of quinoa peptide-zinc chelate

Zinc deficiency affects over 2 billion people worldwide, largely due to poor dietary absorption caused by inhibitors such as phytates. Conventional zinc supplements often show low bioavailability in the intestinal tract. Peptide-zinc chelates offer a promising alternative, yet quinoa-derived peptides remain underexplored as zinc carriers. This study aimed to prepare quinoa peptide-zinc chelate and characterize its physical, chemical, and functional properties.

Quinoa peptides were obtained by enzymatic hydrolysis and chelated with zinc under optimized conditions. Amino acid analysis showed increased contents of glutamic acid (from 21.03 to 23.62 mg g^-1), arginine (from 10.15 to 12.43 mg g^-1), and lysine (from1.45 to 2.23 mg g^-1) after chelation, indicating these as primary binding sites. Scanning electron microscopy and particle size analysis revealed reduced particle size (from 219.73 to 113.93 nm). Fourier transform infrared spectroscopy confirmed the involvement of H, COOH, and CO groups. Quinoa peptide-zinc chelate exhibited superior zinc solubility (95.64%) during simulated gastrointestinal digestion compared to zinc acetate (92.31%) and demonstrated significant antioxidant activity (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate scavenging rate: 84.53%).

These findings establish quinoa as a viable source of zinc-chelating peptides and support quinoa peptide-zinc chelate as a functional ingredient for enhancing zinc bioavailability. © 2026 Society of Chemical Industry.