Optimization of spray-dried green tea polyphenol microcapsules using a yeast-derived polysaccharide-rich fraction: encapsulation performance, structural characterization, and controlled release behavior

Abstract

Polyphenols are highly susceptible to oxidative, thermal, and photodegradation, limiting their functional efficacy in food systems. This study developed a sustainable microencapsulation approach using yeast-derived polysaccharides from brewer's spent yeast, combined with maltodextrin, to enhance polyphenol stability. Spray-drying conditions were optimised via a Box-Behnken design, yielding high encapsulation efficiency (90.49%) and yield (41.80 mg g -1 ) under optimal parameters (0.44 w w -1 , 143 °C, 5.3 mL min -1 ; R² > 0.96). Structural analyses (SEM, FTIR) confirmed successful encapsulation and typical particle morphology. Encapsulation markedly improved resistance to thermal, oxidative, and photodegradation compared to free extracts. Release studies in simulated food and gastrointestinal systems revealed matrix-dependent behaviour, with maltodextrin-soy protein systems showing rapid release (~80%) and maltodextrin-polysaccharide systems enabling sustained release (~50-55%). Encapsulated polyphenols retained bioactivity during digestion. Overall, yeast-derived polysaccharides represent a sustainable and effective wall material for highefficiency microencapsulation and controlled delivery in functional food applications.