Processing-driven changes in sorghum protein digestibility and phenolic bioaccessibility: metabolomics and computational study
Year: 2025
Type: conference-paper
Abstract: Sorghum grains (Sorghum bicolor L.) are increasingly recognized for their agronomic advantages and health benefits linked to phenolic compounds (PC). However, interactions between kafirins, the main storage proteins, and PC can limit in vitro protein digestibility (IVPD) and phenolic bioaccessibility. Processing methods can disrupt these interactions, enhancing nutrient availability. This study aimed to elucidate protein-phenolic interactions and to evaluate the effects of sorghum germination (16 °C, 72/144 h; n = 9), dehulling (~15% removal; n = 12), and boiling (1:6 sample-to-water ratio, 30 min; n = 24) on PC bioaccessibility and protein digestibility. Protein-phenolic interactions were assessed by molecular docking. Gastrointestinal digestion was simulated using INFOGEST protocol to determine IVPD (Kjeldahl method) and PC bioaccessibility (UPLC-ESI-QTOF/MS untargeted metabolomics with customized databases). Data were analyzed using XLSTAT and MetaboAnalyst 6.0. Molecular docking confirmed strong protein-phenolic interactions, with distinct preferential binding sites and interaction forces depending on PC class. Metabolomics detected ~6,000 ions and PCA analysis showed a 62% variation in phenolic profile post-digestion. Euclidean clustering indicated the higher (negative) impact of dehulling on phenolic bioaccessibility, with a 68% reduction in flavonoids and significant losses of hydroxycinnamic and hydroxybenzoic acids. Germination showed dual impact: it enhanced phenolic acids bioaccessibility and declined flavonoids. Cooking had a minimal impact on whole-grain PC; but improved catechin and phenolic acid in bran fractions. Dehulling improved IVPD by 77% through removal of phenolics and phytic acid that hinder protease activity. Conversely, cooking reduced it by 27% and 17% in whole and dehulled grains, respectively. Results suggest protein-phenolic complexes modulate both proteolysis and phenolic release during digestion. Overall, germination was the most effective processing method, enhancing protein digestibility and preserving key PC bioaccessibility. Our findings identify processing strategies that preserve PC and improve protein digestibility, reinforcing sorghum's potential as an innovative cereal for food applications.
Source: HAL
Language: English
Subfield: Biochemistry (medical)
Field: Medicine
Domain: Health Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W7203958663