Abstract
We investigated the changes in the properties of the bolus while chewing mashed potato with added oil and fats to elucidate the swallowing characteristics. The hardness, yield stress and horizontal resistance force of the bolus for the samples with added liquid (BPW and BPO) were significantly lower than those for the samples with added solid (BPF and BPS). The samples with added liquid (PW and PO) and mixed with saliva after 5 times chewing gave close to a swallowable bolus, while the samples with added solid (PF and PS) needed chewing 10 times or more. Microscopic observation of the dispersion of the oil in the bolus of those samples with added oil (BPO) showed fine oil droplets between the potato cells after 5 times chewing, while the bolus of the samples with added solid fat (BPF and BPS) had a separate aqueous layer (potato cell) and fat layer (solid fat) after 10 times or more chewing. These results indicate the importance of ease of mixing with saliva in the process of chewing and of the state of oil and fats dispersed in the bolus to produce suitable swallowing characteristics for mashed potato.
