Blueberry Flavor Biochemistry

In an attempt to identify specific biochemical breeding targets associated with blueberry flavor, the use of consumer-assisted selection was implemented through large consumer sensory panels in conjunction with biochemical profiling of blueberry fruit. Over the course of three years, 217 repeat-panelists rated the fruit quality parameters of overall liking, texture, sweetness, sourness, and flavor intensity for 19 blueberry cultivars in 30 sensory panels. Glucose, fructose, sucrose, soluble solids (SS), titratable acidity (TA), pH, and 53 volatile compounds were quantified for each sample. Linear regression was employed to visualize relationships between sensory measurements and the primary biochemical components. Of 153 total blueberry samples assayed in sensory panels, every sample scored in the positive region of the hedonic scales for overall liking and texture liking. Overall liking of blueberries was significantly related (P < 0.001) to favorable texture (R²=0.60), and intensities of sweetness (R² = 0.49), flavor (R² = 0.45) and sourness (R² = 0.04). The relationship between flavor intensity and texture liking was also very linear (R² = 0.47) and highlights the integration of discrete senses in the brain. Perceived sweetness was best explained by measures of sugars, including SS (R² = 0.30), fructose (R² = 0.30), total sugars (R² = 0.27), and glucose (R² = 0.19). Although significant, measures of sucrose were much less suitable as a predictor of sweetness (R² = 0.05) likely due to very low concentrations in blueberry fruit. Overall liking and sweetness were negatively correlated with TA (R² = 0.19, R² = 0.30), while TA explained over half of perceived sourness (R² = 0.53). An even better explanatory variable of perceived sourness was pH (R² = 0.58). A partial least squares (PLS) regression analysis was constructed to reveal further interactions of volatile compounds contributing to liking and sensory intensities. Volatiles have previously been implicated in sweetness and flavor intensity in fruits such as strawberry and tomato, and comparatively it appears that blueberry volatiles behave uniquely. This model can be used to target up- and downregulation of particular compounds in blueberries for increased consumer favor. To please the greatest number of consumers, focus should be placed on developing sweeter, more flavorful blueberries with good texture attributes, in addition to common commercial traits such as yield and disease resistance.