Abstract
Sweet potato tempura was deep fried at 160°C, 180°C, and 200°C to visually understand the water behavior of food ingredients during the deep frying and determine whether the quality of the finished product could be evaluated using visual indicators. The change in the contrast values of the oil surface images during the deep frying was consistent with the water evaporation rate, indicating that the alteration in water evaporation from tempura over time can be estimated using such values. The water behavior of the batter and sweet potatoes was examined by substituting the water in the batter with heavy water. Immediate water evaporation post-deep frying originated from the batter, with the subsequent one from the sweet potatoes. The tempura quality was optimal when the potatoes were deep fried at 160°C, wherein minimal water evaporation occurred, the sweet potatoes retained water, and the batter maintained an adequate water content. These results suggest that evaluating the quality of sweet potato tempura using contrast values as visual indicators is feasible, given that water behavior during the deep frying can be estimated based on the alterations in water evaporation rates.
