AUTOMATED OPTICAL-SCANNING FOR RAPID SIZING OF CHEWED FOOD PARTICLES IN MASTICATORY TESTS

Analysis of the reduction in sizes of particles after chewing has been a standard method for assessing masticatory efficiency for over 40 ye ars, but the sizing of particles with sieves is very time consuming. A rapid simple method of measuring chewed almond particle sizes by an o ptical scanning method has been developed and is described. The aim of this study is to validate the accuracy, repeatability and speed of th e application of an optical scanning system in measuring chewed partic les. To determine the accuracy, paper circles were measured and compar ed with the travelling microscope measurements. The effect of orientat ion of the images was assessed by measuring three irregular shaped pie ces of paper and three different sized pieces of chewed almonds. Measu rements were taken singly at 18-degrees increments from 0-180-degrees orientations with each piece of paper. To assess the repeatability of measuring chewed particles, the particles from a single masticated alm ond washed with water and absolute alcohol were spread, separated and measured by the optical scanning system. The samples were then remeasu red 10 times. The reproducibility of the method was investigated using three repeated masticatory tests for each subject in a group of 13 yo ung dentate subjects. The speed of spreading the particles and of meas urement was assessed. The absolute error range for a mean area of 31 m m2 was 2.85% to 7.32% with a mean of 3.86%. The relative accuracy of m easurement was higher for larger particles but in no case was the stan dard deviation > 0.4 mm2. The repeatability with different spreads of a chewed almond showed each time the particles were spread there was a small difference in sizing. This was again +/- 0.44 mm2 for an averag e sized particle (CV = 5.4%). The overall spreading, plus the machine time for measuring the total number and sizes of particles > 1 mm, plu s analysis of size distribution could normally be completed within 6 m in. It can be concluded that the application of the optical scanning m ethod gives fast and accurate measurement, counting and sizing of chew ed particles.