Enhancing Protein Digestibility, Bioaccessibility, and Nutrient Retention in Faba Beans Using Nano-Zinc Oxide and Thermal Treatments

This study examines the impact of thermal treatments (steaming and autoclaving) and nano-zinc oxide (Nano-ZnO) foliar applications on the nutritional properties of Faba bean (Vicia faba L.) variety Sakha 1. Changes in chemical composition, mineral contents, particle size distribution, color properties, protein digestibility, bioaccessibility, antioxidant activity, and phenolic compound content. Thermal processing treatments especially autoclaving, significantly enhanced protein, dietary fiber, and ash content, also showing the highest protein digestibility and bioaccessibility for Faba seeds. While Nano-ZnO applications further increase protein levels, with steamed beans which treated with 2 g·L⁻¹ Nano-ZnO showing the most significant improvements. These combined treatments also reduce phytic acid levels and boost antioxidant activity, particularly in steamed Faba seeds samples. Thermal treatments generally lower mineral content in compare with the other samples, Nano-ZnO applications, especially at 2 g·L⁻¹, retain higher mineral levels compared to untreated controls. FTIR analysis indicates structural changes in proteins due to thermal treatments, and color analysis shows significant variations in lightness and color components. In vitro protein digestibility significantly improves with thermal treatments, reaching 80.83% in autoclaved Faba samples. Protein bioaccessibility also increases, with the highest value of 33.71% observed in autoclaved beans treated with Nano-ZnO.