The aim of this study was to investigate the influence of D-amino acids (D-AAs) on the food flavor profile of fermented foods. First, the content of fifteen D-AAs in eight soy sauces, eight soybean pastes and eight cheeses were analyzed by the HPLC method using derivatization reagents. Ten D-AAs in the soy sauces, ten D-AAs in the soybean pastes and twelve D-AAs in the cheeses were detected, and the minimum value of total D-AA concentration among the all foods was 1.3 mM. Second, two sensory evaluations by the Constant stimuli method and the TimeIntensity method were conducted to evaluate the influence of the D-amino acids at 1 mM concentrations on the profile of the five basic tastes (sourness, bitterness, saltiness, sweetness, and umami). Five basic taste solutions (0.025% citric acid, 0.075% caffeine, 1% NaCl, 4% sucrose, and 0.5% MSG) were prepared, to which were added 1 mM D-AA. From the results of the sensory evaluations, we found that D-Asp significantly suppressed sourness and bitterness, and that D-Pro strengthened continuity, sweetness, and umami compared with L-enantiomer. These results suggest that D-AAs play crucial roles in the fundamental tastes of fermented foods.
