The impact of different drying methods on quality indicators of red currants (Ribes rubrum L.)

Abstract

Fresh red currants (Ribes rubrum L.) were dried by convective drying, vacuum drying and lyophilization in order to compare quality of samples dried by different techniques. Physico-chemical properties of the red currants were studied in all applied techniques. Moisture content, water activity, total color change, shear force, rehydration capability, total phenolics content, total flavonoids content, monomeric anthocyanins and antioxidant activity were investigated as the most suitable quality indicators. The lowest loss of nutritionally valuable components and the highest antioxidant capacity were observed in samples dried by lyophilization, where was also noticed: the lowest moisture content and aw value, the lowest total color change and the highest rehydration capability. In vacuum dried sample (65°C, 30 mbar and 6 h) was observed the highest content of flavonoid compounds. The lowest shear force was observed in convectional dried sample (45°C, atmospheric pressure and 12.6 h).

Keywords

• ribes rubrum l.
• vacuum drying
• convective drying
• lyophilization
• physico-chemical properties