Aim Food bolus preparation plays an important role in swallowing food. The ability to carry out oral functions varies with age, and the same might be true of the ability to prepare food boluses. Previously developed methods for assessing food bolus preparation were not able to evaluate swallowed boluses; that is, the boluses were spat out before they were swallowed. The aim of the present study was to evaluate food bolus preparation in older adults using videoendoscopy, and to compare the food bolus preparation abilities of older adults and younger healthy adults. Methods The participants were 30 older adults and 30 younger healthy adults. None of the participants showed any symptoms of dysphagia or eating difficulties. In each examination, an endoscope was inserted into the nasal passage, and the participant was instructed to eat cooked rice. The grinding, mixing and aggregation of each bolus was graded from 0 to 2, with higher numbers indicating more marked grinding, mixing and aggregation. We simultaneously investigated the number of chewing cycles. Results The older adults showed higher grinding scores and lower mixing scores than the younger healthy adults. However, neither of these differences was significant. In contrast, the older adults showed significantly lower aggregation scores and carried out a significantly greater number of chewing cycles than the younger healthy adults. Conclusions Using videoendoscopy, we found that older adults showed lower aggregation scores and carried out a greater number of chewing cycles than younger healthy adults. These results suggest that older adults are less able to prepare food boluses than younger healthy adults. Geriatr Gerontol Int 2017; 17: 226–231.