Vacuum drying of red currant (Ribes rubrum L.): Physical and chemical properties and kinetic modeling

Abstract

Red currants (Ribes rubrum L.) were dried by vacuum drying on different drying temperatures (30, 40, 50, 60 and 70 °C) at constant pressure (20 mbar). The main goal of the research was to investigate changes of physical and chemical properties of red currants at different conditions of vacuum drying process. Moisture content, water activity, rehydration power, total color change, shear force and total monomeric anthocyanin compounds were used as the most suitable quality indicators of dried red currant. The lowest moisture content, total color change and the highest rehydration power were noticed in the red currant sample dried on 60 °C, 20 mbar, 16 h, while the lowest water activity, shear force and the highest content of total monomeric anthocyanins were observed in the sample dried on 40 °C, 20 mbar, 40 h. Five empirical models (Henderson-Pabis, modified Henderson-Pabis, simplified Fick's diffusion, Peleg's and two term) were used for description of vacuum drying process.

Keywords

• drying temperature
• water activity
• rehydration
• color
• shear force
• total monomeric anthocyanins