Upcycling cheese whey into a raspberry-enriched fermented beverage with sensory characterization and assessment of phenolic compounds during simulated gastrointestinal digestion.

BACKGROUND: Cheese whey valorization requires processing strategies that yield acceptable beverages while characterizing their composition and behavior during digestion. This study developed a fermented whey beverage enriched with raspberry extract and evaluated extraction conditions, sensory acceptance, and changes in phenolic markers and antioxidant responses during simulated gastrointestinal digestion. RESULTS: Partially deproteinized whey was fermented with Lactobacillus helveticus and formulated with raspberry extract at 100, 200, or 300 mL L-1. Steam-assisted extraction for 30 min provided the highest juice recovery, although monomeric anthocyanin concentrations were lower than after shorter extraction times. The formulation containing 300 mL L-1 extract received the highest overall acceptability score from 11 untrained panelists (6.18 ± 0.75 on a seven-point scale). Gastrointestinal endpoints were evaluated in independent digestion vessels. Mean total phenolic concentrations were 149.2 and 211.5 mg gallic acid equivalents L-1 at the oral and gastric endpoints, respectively, and ranged from 52.9 to 125.3 mg L-1 at intestinal endpoints. Monomeric anthocyanins were detected at oral and gastric endpoints but were not detected at intestinal endpoints. 2,2-Diphenyl-1-picrylhydrazyl and oxygen radical absorbance capacity assays showed distinct response patterns, with measurable antioxidant capacity throughout digestion. CONCLUSION: Raspberry enrichment offers a promising route for valorizing cheese whey into a fermented beverage with favorable preliminary sensory acceptance. Detectable antioxidant capacity throughout simulated digestion supports further investigation of this formulation. These findings provide a foundation for optimizing whey-fruit beverages and validating their properties through controlled digestion studies and broader consumer evaluation. © 2026 Society of Chemical Industry.