Optimization of Drying Conditions of Xanthosoma sagittifolium (Tannia) Tubers in Tray Dryer Using Response Surface Methodology

Drying conditions for Xanthosoma sagittifolium tubers were optimized using response surface methodology. A face‐centered central composite design with two numerical factors and one categorical factor was selected for conducting the experiments. The numerical factors selected were air temperature from 50 to 70C, and drying time from 4 to 8 h while shape of the cut tubers i.e., slices or cubes was the categorical factor. The responses investigated were water loss, final moisture content, rehydration coefficient and peak viscosity. The study revealed that the effect of all the factors was significant on the responses. The optimum condition obtained using the desirability function for achieving the desired product was found at the temperature of 68.57C and the drying time of 5.51 h for slices. The values of moisture content, water loss, rehydration coefficient and peak viscosity at the optimum drying condition were 0.43% dry basis, 68.55 g/100 g sample, 0.84 and 4039.4 cP, respectively. PRACTICAL APPLICATIONS: The tubers of Xanthosoma contain reasonable amounts of calcium, phosphorus, and vitamins A and B. The starch present in Xanthosoma tubers is easily digestible because of its small granule size. The protein and dietary fiber content of the edible portion is also high as compared with other root and tuber crops. It can be used in the preparation of baby foods and diets of people allergic to cereal proteins. Although the production of Xanthosoma sagittifolium is high worldwide and has the potential of meeting the energy requirements of the consumer because of its high starch content and better starch quality, there are very few studies related to drying of X. sagittifolium tubers to increase the shelf life of the product. Therefore, the present study becomes important as proper understanding of the drying process of Xanthosoma tubers is necessary for the process to become industrially feasible.