Fermentation of American elderberry juice yields functional phytochemicals for spray dried protein-polyphenol...

American elderberry juice (EBJ) and fermented elderberry juice (EBF) were spray dried using two different carriers: S. cerevisiae yeast (SC), used for juice fermentation and as encapsulating agent, and pea protein, to produce protein-polyphenol ingredients. The spray drying (SD) performance (solids recovery, SR; phenolic retention, PR) and quality attributes (physicochemical and functional properties, phytochemical content and bioaccessibility after in vitro digestion) of eight treatments of spray dried elderberry particles were determined. The total phenolic content (TPC) of EBJ (4476 ± 169 mg GAE/L) increased by 27 % after fermentation (EBF: 5706 ± 199 mg GAE/L). The SD performance of EBF (SR > 50 %; PR 55.7-63.9 %) was significantly higher (p < 0.05) compared to EBJ (SR < 50 %; PR 28.6-42.8 %). Stable (a_w < 0.3) protein-polyphenol particles, with pH-dependent solubility that increased as pH went from 4 to 10, were produced. The TPC of EBF-derived particles (26.2-28.7 mg GAE/g) was 22-31 % higher than EBJ-derived particles (20.4-21.9 mg GAE/g) and anthocyanins were the major phenolic group detected. An increase in nearly all phenolic metabolite concentrations was observed after fermentation, and an additional increment was observed after spray drying. Phenolic bioaccessibility improved (17-25 % higher) after S. cerevisiae fermentation and when using SC as the drying carrier compared to phenolics source (EBJ or EBF). Overall, here we show a sensible strategy to produce protein-polyphenol particles with better SD performance and enhanced phytochemical content and profile. Our fermentation and spray drying strategy provides practical and efficient means to produce functional fruit ingredients for the emerging clean-label, health-oriented market.