Mechanistic Insights into Lignin's Inhibition of Gluten Digestibility: Evidence from In Vitro Static Digestion

This study investigates the inhibitory effects of lignin on gluten digestibility and elucidates the underlying mechanism using static in vitro digestion protocols involving pepsin and pancreatin. Gluten digestibility was evaluated based on the degree of protein hydrolysis (DH), peptides' profile, and free amino acids (AAs) content. The interactions between lignin and gluten under digestive conditions and their impact on proteolytic enzyme activities were examined through various analytical techniques, including scanning electron microscopy (SEM), viscosity measurements, ζ-potential analysis, and enzyme kinetics. Results reveal that lignin significantly impairs gluten digestibility by inducing the formation of protein aggregates, leading to distinct intermediate peptides and reduced levels of key AAs such as aspartic acid, phenylalanine, proline, and histidine. These findings offer valuable insights into gluten-lignin interactions and highlight lignin's potential applications in the food industry, particularly as a functional additive to modulate nutrient digestibility.