Physicochemical characterization of sorghum husk proteins and development of glutelin-based sub-micron particles for lycopene encapsulation

Abstract

Sorghum is a drought-tolerant, high-yielding cereal crop rich in carbohydrates, proteins, and dietary fiber, rendering it a valuable resource for food, feed, and biofuel industries. Sorghum husks, the fibrous by-products generated druing grain processing, remain largely underutilized. In this study, sorghum husk proteins (SHPs) were isolated and systematically characterized in terms of their chemical composition, physicochemical properties, antioxidant activities, and carrier potential for functional compounds. The results demonstrated that glutelin exhibited superior foaming ability and stability, disulfide bond content, and antioxidant activity in chemical and cell-based assays. Additionally, hyaluronic acid (HA) and polyethyleneimine (PEI)-modified glutelin-based sub-micron particles (SMPs) significantly improved the stability of encapsulated lycopene (LYC), mitigating its degradation by 14.38%–70.02% under thermal stress, 16.18%–59.80% under ultraviolet irradiation, and 16.84%–40.60% under oxidative stresses. These SMPs also exhibited potent in vitro anti-inflammatory activity by suppressing the secretion of key inflammatory mediators, including tumor necrosis factor α (TNF-α) (15.48%–56.70%); interleukin-1β (IL-1β) (50.81%–72.62%); interleukin-6 (IL-6) (25.90%–73.02%); nitric oxide (NO) (25.32%–78.31%); prostaglandin E2 (PGE2) (35.76%–76.30%), and cyclooxygenase-2 (COX-2) (42.20%–66.15%). Collectively, these findings suggest that SHPs, particularly glutelin, possess potential as multifunctional biomaterials for functional food delivery. Chemically modified SHPs may represent a promising strategy for enhancing the retention of encapsulated bioactive compounds, pending further in vivo validation.