Effect of Unit Operations on Food Particles – Evaluated by image analysis and correlated with mechanical tests

Abstract: In order to successfully produce food products containing less damaged particles (approx. 1 cm3) it is important to investigate at which limit that the particle could be subjected to processing. This study attempted to predict particle breakage using mechanical test with image analysis as method validation. The characterization of different coarse particles was done using the developed methods on mechanical tests and image analysis. The mechanical tests involved double compression (texture profile analysis), that can measure hardness, maximum stress, modulus, springiness, cohesiveness, and chewiness. Single compression and puncture tests measured bio-yield stress. Results show that the tests gave different trends of particle strength. Representative particles were run on the designed rig composed of three-unit operations: agitator, wing rotor pump and restriction pipe. Morphological changes were measured by image analysis indicating the breakage due to the unit operations. The results of image analysis cannot be correlated to the mechanical properties because not all particles did significantly break. For rapid measurement of particle breakage, sieving analysis is recommended on obtaining particle size distribution. Nevertheless, image analysis complements to this method as it can still provide shape parameter information that is also helpful on understanding mechanism of particle breakage.