Although enzymatic hydrolysates of soy protein isolate (SPI) have physiological functionality, partially hydrolyzed SPI exhibits bitter taste depending on proteases and degree of hydrolysis (DH). To determine proteolysis conditions for SPI, it is important to evaluate bitterness during enzymatic hydrolysis. Taste dilution analysis (TDA) has been developed for the screening technique of taste-active compounds in foods. The objectives of the present study were to evaluate bitterness of enzyme-hydrolyzed SPI by TDA and to compare bitterness of SPI hydrolysates with respect to kinds of proteases and DH. SPI was hydrolyzed at 50 degrees C and pH 6.8 to 7.1 to obtain various DH with commercial proteases (flavourzyme, alcalase, neutrase, protamex, papain, and bromelain) at E/S ratios of 0.5%, 1%, and 2%. The DH of enzymatic hydrolysates was measured by trinitrobenzenesulfonic acid method. The bitterness of enzymatic hydrolysates was evaluated by TDA, which is based on threshold detection in serially diluted samples. Taste dilution (TD) factor was defined as the dilution at which a taste difference between the diluted sample and 2 blanks could be detected. As DH increased, the bitterness increased for all proteases evaluated. Alcalase showed the highest TD factor at the same DH, followed by neutrase. Flavourzyme showed the lowest TD factor at the entire DH ranges. At the DH of 10%, TD factor of hydrolysate by flavourzyme was 0 whereas those by protamex and alcalase were 4 and 16, respectively. These results suggest that TDA could be applied for the alternative of bitterness evaluation to the hedonic scale sensory evaluation.

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Owing to difficulties associated with profiling and differentiation, it is challenging to identify drivers of liking of samples that contain complex flavor but have subtle differences. This study compared the efficacy of free‐comment (FC) analysis with descriptive analysis (DA) for profiling the sensory characteristics of tomato sauce with added garlic flavoring to identify the drivers of liking. Seven garlic tomato sauce samples were prepared by the addition of different garlic flavorings or crushed garlic. FC was conducted using 82 consumer panelists and DA was performed using eight trained panelists. Compared with the DA, the FC revealed the differences between samples better by using the concepts relevant to consumers and the descriptors with hedonic connotations. FC better identified the drivers of liking for the products with subtle differences, particularly in odor and flavor, but the standardized descriptors of DA could not sufficiently explain them due to a poor correlation with liking. Practical applications As the consumer demand for healthful yet flavorful foods increases, the flavors of foods need to be finely adjusted using flavorings to meet consumer expectation. This can cause subtle changes in flavors that may be recognized but are not easy to verbalize or to distinguish, even by trained panelists. In such cases, it is difficult to derive the sensory determinants of liking that may be critical to guide product development. This study compared FC and DA to examine if the more spontaneous and richer descriptions obtained from FC could efficiently profile sample sets with subtle flavor differences. This study will aid the selection of efficient profiling methods for products with complex flavors.

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