Increased aroma content of gummy jelly prolongs chewing strokes and chewing duration to the swallowing threshold

Mastication is a physiological process that facilitates swallowing, digestion, and flavor perception. The timing from chewing to the swallowing threshold may be influenced by flavor perception, including retronasal aroma reaching the nasal cavity during chewing, as well as by oral and pharyngeal function. We aimed to examine the effects of oral function and retronasal aroma on the swallowing threshold by modifying the aroma content of standardized gummy jellies. Thirty adults (15 women, 15 men; age 26.4 ± 3.4 years) participated in this study. The test food was a gummy jelly standardized for masticatory performance assessment, with four levels of aroma content. Masticatory performance was measured using gummy jellies with image analysis, and the stimulated saliva flow rate was measured using flavorless paraffin wax. Retronasal aroma intensity was measured using a portable odor sensor positioned at the nostrils under conditions close to natural eating. Participants ingested aroma-adjusted gummy jellies three times, in random order, and we measured the retronasal aroma intensity, number of chewing strokes, and chewing duration until reaching the swallowing threshold. Flavor perception during chewing was evaluated using a visual analog scale. The results showed that retronasal aroma intensity increased with higher gummy jelly aroma content. Furthermore, chewing strokes until reaching the swallowing threshold increased with higher aroma content, even after adjusting for masticatory performance and salivary flow rate. No significant differences were observed in visual analog scale scores. These findings suggest that enhanced retronasal aroma may contribute to prolonging mastication before swallowing under near-natural eating conditions. • We used gummy jellies with varying aroma content to evaluate swallowing threshold. • Retronasal aroma during chewing was measured in conditions close to natural eating. • Higher aroma content increased chewing strokes and chewing time before swallowing. • Aroma content remained associated with chewing strokes after adjustment. • Retronasal aroma may influence the timing of swallowing initiation.