Mulberry Leaf Glutelin: Physicochemical, Functional, and Pancreatic Lipase Inhibitory Activity of Seven Varieties

Mulberry leaf glutelin (MG), a nutrient-rich protein fraction from mulberry leaves, remains underutilized due to limited studies on its physicochemical functional properties and biological activities. In this study, seven varieties of MG (TSG, DSG, 109G, C1G, C2G, C3G, C4G) were evaluated for amino acid composition, secondary structure (FTIR), solubility, water-holding capacity (WHC), oil absorption capacity (OAC), foaming capacity (FC), foam stability (FS), emulsifying activity index (EAI), emulsion stability index (ESI), in vitro digestibility, and pancreatic lipase inhibitory activity (PLI). The results showed that MG contains four secondary structures and 17 amino acids, being rich in glutamic acid, aspartic acid, and leucine. C3G exhibited superior solubility (96.32%) at pH 10, while C4G showed optimal WHC (9.27 g/g), FC (73.75%), and FS (92.80%). TSG exhibited the highest OAC (9.58 g/g) and EAI (15.79 m²/g), and DSG demonstrated an excellent ESI (117.25 min), digestibility (88.17%), and PLI (70.54%). These findings provide valuable insights for the application of MG in food processing and innovation, enhancing its potential value for the food industry and human health.