Evaluation of the synergistic olfactory effects of diacetyl, acetaldehyde, and acetoin in a yogurt matrix using odor threshold, aroma intensity, and electronic nose analyses

Despite intensive analyses of yogurt flavor, the syn-ergistic effects of the key aroma compounds on sen-sory responses and their optimum concentration ranges remain less well-documented. This study investigated the odor thresholds, optimum concentration ranges, and perceptual actions of diacetyl, acetaldehyde, and acetoin in a yogurt matrix. Our results show that the odor thresholds of diacetyl, acetaldehyde, and acetoin in the yogurt matrix were 5.43, 15.4, and 29.0 mg/L, respectively, which were significantly higher than the corresponding values in water. The optimum diacetyl, acetaldehyde, and acetoin concentration ranges were found to be 6.65 to 9.12, 25.9 to 35.5, and 37.3 to 49.9 mg/L, respectively. In Feller's additive model, the addition of each compound led to a significant reduc-tion in their odor threshold in the yogurt matrix, thus demonstrating the synergistic effects of the compounds. In the sigma-tau plot, various concentrations of compounds were associated with various degrees of additive be-havior with respect to the aroma intensity of the yo-gurt matrix, thus demonstrating the synergism among these compounds in increasing the overall aroma in-tensity. The optimal simultaneous concentration ratio of diacetyl: acetaldehyde: acetoin was determined to be 4.00:16.0:32.0 mg/L. The specific synergistic effects were also confirmed by an electronic nose analysis and aroma profile comparison. In summary, these 3 aroma compounds exhibited synergistic effects in a yogurt ma-trix, thus providing a theoretical basis for the enhance-ment of flavors in dairy products. tion to tributor