Optimization of Wild Blackthorn (Prunus spinosa L.) Purée Drying: Effect of Egg Albumen Concentration Using Response Surface Methodology

Prunus spinosa L. (wild blackthorn) purée is an effective, nutrient-dense matrix that is rich in polyphenols, dietary fiber, and ascorbic acid, possessing significant potential as a functional food ingredient. This study investigated the technological valorization of wild blackthorn purée using convective and infrared-assisted foam-mat drying, evaluating the impact of temperatures (50, 60, and 70 °C) on bioactive profiles, antioxidant activity, color parameters, and powder flowability. Results indicated that the Midilli and Page models proved the best fit for the experimental drying kinetics, with higher effective moisture diffusivity (Deff) observed in infrared-assisted systems. Convective foam-mat drying (60 °C, 5% egg albumen) resulted in a higher anthocyanin content compared to the control (0% egg albumen), corresponding to a relative increase of 20.8% based on HPLC analysis. Under infrared drying at 60 °C, the 10% egg albumen formulation showed a relative increase of 7.8% compared to the corresponding control. Samples without egg albumen (0% EA) exhibited baseline polyphenolic content under both drying techniques. Samples obtained without egg albumen (0% EA) under optimized conditions exhibited improved color stability and maintained polyphenolic content. Overall, the results highlight the combined effect of drying method, temperature, and egg albumen concentration on the quality of blackthorn purée powders under the studied conditions.