Effects of different processing methods on bioaccessibility of phenolic compounds in flaxseed meal

Flaxseed meal is a rich source of phenolic compounds, yet its industrial application remains limited due to poor bioaccessibility of bound phenolic. This study aimed to systematically compare the effects of steam explosion (SE), extrusion (EF), and fermentation (FP) on the bioaccessibility of phenolic compounds in flaxseed meal using in vitro gastrointestinal digestion and colonic fermentation models. SE and EF significantly increased free phenolic release by 125.81% and 116.51%, respectively, during intestinal digestion. FP elevated secoisolariciresinol diglucoside (SDG) levels by 354.9% compared to the control. SE-treated samples exhibited the highest acetic acid production (28.72 mg/mL) and microbial α-diversity. All treatments modulated gut microbiota by enriching Bifidobacterium and suppressing Enterobacteriaceae. SE and EF enhance phenolic bioaccessibility via cell wall disruption, while FP promotes metabolite transformation. These findings provide a mechanistic basis for tailoring flaxseed meal processing strategies for functional food development.