Physicochemical characterization and phenolic compound content of flour from blended juice residues

BACKGROUND: The production of fruit juices generates substantial amounts of residue, including peels, seeds, pomace, stalks, and leaves, which are rich in nutritionally relevant compounds, such as fiber and bioactives. The aims of this study were to evaluate drying conditions for converting mixed juice residue, composed of apple, beetroot, lemon, and ginger, into flour; to characterize its physical, chemical, and functional properties; and to assess its application in food products. RESULTS: Drying the residue at 70 °C for a shorter time produced flour with superior color retention, higher phenolic compound content, and greater betacyanin concentration than fresh waste and the other flours dried at 50 and 60 °C. Ten phenolic compounds were identified. The flour demonstrated antifungal activity against Fusarium species, indicating its potential as a natural preservative ingredient. Partial replacement of wheat flour with residue flour in cake formulation yielded a product with over 80% overall acceptance in sensory analysis and a 40% higher fiber content than the cake without added residue flour. CONCLUSIONS: The results demonstrate the viability of using agro-industrial residues as nutritionally valuable food ingredients that are sensorially attractive to consumers. This approach aims to sustainably valorize important food components that are typically discarded. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.