Odor-induced sweetness enhancement: EEG evidence for olfactory and gustatory cross-modal interactions.

Reducing sugar content while maintaining perceived sweetness is a major challenge in beverage formulation. This study combined sensory evaluation and electroencephalography (EEG) to investigate how varying odor intensities influence sweetness perception in sucrose solutions. Sixteen participants evaluated solutions with matched sugar content but different odor levels while EEG signals were recorded. Behavioral results revealed an inverted U-shaped response: beverages with moderate odor intensity elicited the highest perceived sweetness, increasing ratings by 14.7% relative to the sucrose-only baseline (no added odor), whereas high odor intensity slightly reduced sweetness perception by 5.4%. EEG analysis showed that α-band functional connectivity exhibited the strongest and most concentration-dependent modulation, with source localization identifying the temporal lobe as the principal hub coordinating distributed cortical networks. Although changes in individual graph-theoretical metrics were minimal, integrating multiple EEG features through a random forest model enabled accurate classification of sweetness-related conditions, achieving an average accuracy of 84.5%. These findings indicate that sweetness perception arises from distributed, high-dimensional network coordination rather than isolated pathways. By combining sensory and neurophysiological measures, this approach provides actionable guidance for optimizing odor formulations, enabling sugar reduction while maintaining consumer-perceived sweetness.