Textural Properties of Chinese Water Chestnut (Eleocharis dulcis) during Steam Heating Treatment

Chinese water chestnut (CWC) has become one of the most popular foods in China. The textural properties of food contribute considerably to consumer preferences. Fresh fruits and vegetables are normally softened after thermal treatment. However, CWC retains most of its crispness and hardness after steaming. To explore the relationship between thermal processes and sensory changes, a method for measuring the texture of CWC is warranted. This study aimed to examine the textural properties of CWC subjected to varying degrees of thermal treatments using instrumental and sensory methods. Instrumental tests included the shear force test and puncture test, while trained panelists assessed the sensory attributes. Two sensory attributes were selected for evaluation: crispness and hardness. The results indicated that with the extension of thermal treatment time, the crispness and hardness of CWC decreased slightly, while cells and starch grains were damaged. Sensory results showed a significant correlation with shear force index (slope of rising curve) (p < 0.05) and puncture index (slope of rising curve, slope of descending curve and compression work) (p < 0.05). Thereafter, the instrumental tests parameters could be used to establish regression models for predicting crispness and hardness and controlling the quality of CWC products.