Carrier-mediated water state manipulation enables microwave vacuum drying of blackcurrant puree: Sequential...

The addition of carrier agents into fruit puree can modulate water binding, enabling smooth dehydration into high-quality fruit powder under microwave vacuum drying (MVD). Soy protein isolate (SPI), maltodextrin (MD), and β-cyclodextrin (β-CD) were selected as additives to blackcurrant puree (BCP) to form a formulated puree (FP) for producing berry powder. The golden section method was employed to determine the optimal additive ratio in FP. In FP, the additions of MD and SPI cause a shift of free and immobilized water toward a semi-bound state. SPI addition increases the glass transition temperature (T_g) of the dried product above the drying temperature, overcoming the viscous behavior of raw puree. MD addition improves drying feasibility and powder flowability based on lower Carr index and Hausner ratio. The optimal formulation was determined as 86% BCP, 8.5% SPI, 3.3% MD, and 2.2% β-CD, which ensures minimal additive usage while achieving the required drying feasibility and desired quality of the final berry powder. LF-NMR relaxometry and FT-IR spectroscopy reveal distinct shifts in water molecule populations upon additive incorporation via hydrogen bonding and hydrophobic interactions. These shifts suggest that altered water-matrix interactions may underpin the improvements in FP powder quality.