Factors affecting odour-induced taste enhancement

• Odour-induced taste enhancement (OITE) represents a potentially important strategy for sugar reduction. • It is currently uncertain how the taste qualities associated with aromas are linked to OITE. • Evidence shows that non-gustatory cues to sweetness can be combined to enhance sweetness. • It is currently unclear what limits on OITE from combining sweet volatiles might be. • Relative importance of perceiving volatiles vs. their mere presence in OITE effects is also unclear. Reducing the use of calorific sweeteners in sugar-sweetened beverage while, at the same time, maintaining the perceived sweetness is an important issue for the food industry given the growing global obesity crisis, and the need for many consumers around the world to reduce their sugar intake. A number of fruit aromas/volatiles appear to offer a promising route to enhancing the perception of sweetness without adding to the calorific load. However, while a growing body of empirical evidence suggests that this is a promising strategy, as made clear by this narrative review, there are a number of outstanding questions that have yet to be answered in terms of optimising the impact on sweetness offered by the addition of volatile aromas. It is, for example, currently unclear what the maximum sweetness enhancement effect that can be achieved by combining a variety of different volatiles (e.g., those associated with different fruits) before a ceiling or saturation effect is reached. It is also currently unclear how important conscious awareness of the specific volatiles, or aromas, are to odour-induced taste enhancement (OITE) effects. A third outstanding issue concerns whether OITE would occur in the case of olfactory metamers that do not overlap in terms of their volatile composition. One other intriguing issue concerns whether volatiles only come to be associated with taste qualities as a result of associative learning or whether there are some odours that are, for example, naturally (or innately) sweet.