The formation, flocculation and sedimentation of calcium phosphate particles are among the main physico-chemical reactions that occur during the clarification of cane sugar juice. The mechanisms through which processes occur in juice clarification are still poorly understood. This study (being part of a comprehensive investigation to unravel these mechanisms) reports on the size and structure of calcium phosphate particles and aggregates in water and sugar solutions at 20 degrees C using the small angle laser light scattering technique. The average size of the primary calcium phosphate particles was in the range 10.4 +/- 1.1 mu m to 17.5 +/- 1.2 mu m and the scattering exponents, which describe the structure of the calcium phosphate flocs, varied from 1.97 to 2.76. The flocs formed without flocculant are more compact in water than those formed in sugar solution. The compactness of the flocs was also affected by pH of the solution. This effect has been explained by considering the electrical double layer phenomenon. Crown Copyright (c) 2006 Published by Elsevier Inc. All rights reserved.