Quality characteristics of lotus root (Nelumbo nucifera G.) with osmotic treatment depending on drying methods

Abstract

This study aimed to dry lotus root using cold vacuum drying and freeze-drying methods, with the goal of exploring its potential as a new food ingredient or processed product. The dried lotus root was prepared by osmotic treatment the lotus root in a solution containing sucrose, vitamin C, and calcium, followed by drying using either cold vacuum drying or freeze-drying. The sugar content of the osmotically treated dried lotus root varied depending on the sugar concentration of the osmotic solution. Therefore, drying was carried out after osmotic treatment with a 30% sugar concentration. As a result of freeze-drying and cold vacuum drying, the moisture content of freeze- drying lotus root was high, but the water activity was low. There were no significant differences in the optimal acidity, pH, and browning degree based on the drying method. In terms of color, the cold vacuum drying method showed a lower L value and higher yellow and red values compared to freeze-drying. The total polyphenol content was higher in the freeze-drying lotus root than in the cold vacuum drying, and the flavonoid content was also higher in the freeze-drying lotus root. In the future, if the functional quality characteristics of lotus root and powdering processes are further explored based on different drying methods, it is expected that its application as a diverse food ingredients will be expanded.