Composition of free sugars and organic acids in Japanese strawberry cultivars and their influence on the perception of sweetness and sourness

Abstract This study aimed to determine the extent of variations in the ratio of major free sugars to total sugars and major organic acids to total organic acids in strawberry juice with cultivar and harvest season and investigate whether these differences affect the perceived intensity of sweetness and sourness. Eight Japanese strawberry cultivars were simultaneously grown and harvested in different seasons for sugar and organic acid content analyses. In addition, simulated strawberry juices, containing equal total amounts of sugars and organic acids but in different ratios, were prepared based on their analytical values. The perceived intensities of sweetness and sourness of the juices were subjected to sensory evaluation. The results showed a wide range of sucrose compositions, ranging from almost zero to the highest ratio of 36.7% to total sugar. Glucose and fructose were present in approximately equal amounts, with a slight inclination toward more fructose. For organic acids, the highest ratio of citric acid was 87.6%, the lowest was approximately 60.1%, and the remainder comprised malic acid. The results of the sensory evaluation using simulated strawberry juice indicated that sweetness and sourness were significantly more pronounced as the ratio of sucrose to total sugar and the ratio of malic acid to total organic acid increased, respectively. These results suggest that it is essential to consider not only total soluble solids and titratable acidity but also the composition of the sugars and organic acids comprising them when evaluating strawberry taste. Practical Application Total soluble solids and titratable acidity have been used to evaluate strawberry taste; however, how the composition and ratios of the sugars and organic acids that comprise them affect the taste is unclear. This study revealed that, for sugars, an increase in the proportion of sucrose resulted in a stronger perception of sweetness, and for organic acids, an increase in the proportion of malic acid resulted in a stronger perception of sourness. These findings are expected to be useful in future studies evaluating strawberry taste and palatability.