Particle development in apple juice determined by light scattering and electron microscopy

Light scattering was used to detect the kinetic development of particles in apple juices produced with and without oxidation and in procyanidin extracts prepared from these two juices. Particle size developed exponentially in both oxidized and unoxidized juices, suggesting an enzymatic origin for the particle forming reactions. The procyanidin extract from oxidized juices produced particles which grew linearly, suggesting diffusion-controlled aggregation or coalescence of particles. Procyanidins from unoxidized juice showed no particle development over at least 60 days of storage. Electron microscopy showed particles similar to those seen previously and some newly described morphologies. The mechanism of haze particle development is discussed in the light of the light scattering and electron microscopic results.