Oil is extracted from walnut leaves behind large quantities of defatted press cake that is still rich in valuable nutrients. Aspergillus oryzae and Rhizopus oligosporus, two molds traditionally used in Asia, have the necessary enzymes to use the nutrients in the walnut press cake. Walnuts and the press cake contain ellagitannins, known as precursors for ellagic acid and urolithins. In this study, experiments to optimize the solid-state fermentation of walnut press cake were performed in order to liberate ellagic acid from ellagitannins. Extracts of fermented products were then analyzed with an HPLC-DAD to measure the liberation of ellagic acid from ellagitannins. Good growth of R. oligosporus and A. oryzae mycelia on the walnut press cake was observed. A single mold culture was subjected to a hydration of 0.8 mL/g, an addition of 37.5 mmol/kg acetic acid (AA) and 1% NaCl, and an incubation temperature of 25 °C; these were observed to be good conditions for solid-state fermentation for walnut press cake. The highest ellagic acid concentration was obtained at 48 h. At 72 h, degradation dominated the liberation of ellagic acid.

Fruits from rosehip (Rosa canina L.) are gaining popularity due to their content and profile of bioactive components. Rosehip is distinct for its antioxidant, immunomodulatory, and anticancer properties. However, the abundance of these bioactives led to a tart taste, resulting in its consumption mainly in processed form. Due to microbiological safety, pasteurization is the preferred way of processing, which affects the chemical properties of the juice. A promising approach to improve acceptability of rosehip’s physical properties, while preserving its bioactive compounds and adding health-promoting benefits, is to enrich the rosehip juice with functional carriers before drying. The influence of the carrier type (maltodextrin, inulin, trehalose, palatinose) and drying technique (spray- and freeze-drying) on the physical, chemical, and antioxidant properties of pasteurized, and non-pasteurized juice powders was examined in this study. In addition, the ability of powders with functional carriers to inhibit protein glycation was evaluated. Spray drying led to products with improved physical properties in relation to freeze-drying. The addition of carrier substances significantly influenced the antioxidant capacity determined by TEAC ABTS and FRAP methods, whereby the application of inulin and palatinose retained antioxidant capacity better than the frequently used maltodextrin. Moreover, rosehip juice powders showed a promising ability to inhibit protein glycation.