Particle size of solid food after human mastication and in vitro simulation of oral breakdown

Mastication, the first step in food digestion, results in the breakdown of solid food and its lubrication with saliva. Although the rate and extent of starch digestion are closely dependent on the way food is chewed, this fac tor has not been adequately considered in the preparation of food for in vi tro digestion experiments. The purpose of this study was to determine the s ize distribution of starchy food particles before swallowing and to use an in vitro mincing procedure to simulate how food is divided up during chewin g. Foods differing in texture and size (bread, spaghetti and tortiglioni) w ere chewed by 12 healthy subjects and spat out before swallowing. Chewing t ime and saliva impregnation were measured for each mouthful. The particle s izes resulting from experiments with chewed and minced bread and pasta were analysed respectively by light laser diffraction and image analysis. Chewi ng time was longer for bread than pasta, resulting in higher saliva impregn ation. Chewed bread showed a bimodal distribution of particle size (30 mum, 500 mum), whereas both kinds of pasta produced particles of similar size ( 0.5 to 30 mm(2)) after mastication. Mincing reproduced the division of brea d and pasta as achieved by chewing in aa acceptable way. From our results i t seems that the size of particles resulting from mastication depends on fo od texture. We succeeded by wetting and mincing food to prepare food in a s imilar bolus-like form before swallowing. Mincing provides a simple means o f simulating the reduction of food into particles for in vitro digestion st udies.