Optimum mouthful for food comminution in human mastication.

The effect of varying the portion of food offered for chewing (termed the mouthful) on aspects of the oral comminution of salted peanuts was investigated on six human subjects. Particle-size distributions, assessed from a sieving analysis, were similar for different mouthfuls, and could be characterized by a sieve size that would pass 80 per cent of the particles by volume in a distribution. As the food weight was increased, (a) the rate of particle-size reduction of the food declined exponentially, (b) the rate of food surface area production increased, (c) the number of chews to swallow the food increased, (d) the number of chews per unit gram to swallow the food decreased, (e) the food-particle sizes that were swallowed increased. It is hypothesized that the volume of food between the teeth at any chewing stroke depends more on food-particle size than on the weight of food in the mouth. The swallowing of small mouthfuls of peanuts may have depended more on the time to wet particles with saliva than particle size.