Effect of taste recall training using 5 sweet substances on sweet taste sensitivities.

The mechanisms involved in the discrimination of basic tastes have been previously studied. However, the mechanisms that differentiate between various substances within the same taste quality remain largely unexplored. This study aimed to determine whether individuals can distinguish 5 different sweet substances and whether this ability can be improved through taste recall training, serving as an entry point for elucidating the underlying mechanism. Forty healthy individuals were divided into 2 groups: a training group (10 males and 10 females) and a control group (10 males and 10 females). The taste recall training involved 5 sweet substances: glucose, fructose, sucrose, maltose, and lactose. Using the filter paper disc method, participants recalled the taste of the 5 sweet substances at a concentration one level below their taste thresholds and then matched the 5 substances. This training was conducted for 3 consecutive days. There were no significant differences in the number of participants, sex, age, body mass index, oral moisture, or baseline taste sensitivity between the training and control groups. The training group showed a significant improvement in the taste thresholds for all 5 sweet substances compared to the control group (glucose: P < 0.001, fructose: P < 0.001, sucrose: P < 0.001, maltose: P < 0.005, lactose: P < 0.001). These findings suggest that taste recall training enhances taste sensitivity for all 5 sweet substances and may improve both taste thresholds and discrimination performance within the same taste quality.