Influence of food volume per mouthful on chewing and bolus properties

Background: Behaviors relating to food intake, i.e., speed of chewing, number of chews, and bite size, are important for decreasing energy intake, which might reduce excess body weight and thus metabolic risk. This study aimed at investigating the influence of mouthful volume on the number of chews and food bolus properties in addition to clarifying appropriate eating behaviors related to mouthful volume. Methods: Fifteen young Japanese women volunteered to participate. The subjects were asked to spit the food bolus in a glass dish just before swallowing when eating 3 different foods: boiled rice, fish sausage, and peanuts. The 3 physical properties of solidity, adhesiveness, and cohesiveness were measured in the bolus, and the number of chews was noted. Results: The number of chews significantly increased with increasing mouthful volume with all 3 foods; conversely, the number of chews per unit of food weight (g) decreased significantly with boiled rice and fish sausage. Trends were observed for solidity and cohesiveness, which varied with increasing mouthful volumes. Conclusions: Decreased mouthful volume resulted in a greater number of chews per weight of food and more appropriate bolus properties; therefore, a change in mouthful volume could be a useful behavior modification for regulation of energy intake. (C) 2015 Elsevier Inc. All rights reserved.