Effect of storage on cloud stability of cloudy apple juice

Cloud stability of particles in cloudy apple juice during its storage for 120 days at 4, 22 and 40 degrees C is conducted. The juices are added with or without ascorbic acid. The cloud stability of juices during storage is studied by optical microscopy, electron microscopy and size distribution analysis of suspending particles combined with a polyphenols component analysis by high performance liquid chromatography. At the beginning of storage, the turbidity of juice added with or without ascorbic acid decreased quickly because particles of larger size in juices aggregated and deposited, and since there are less larger particles at the upper portion of the bottles, the depositing speed of particles decreases. The loss of total phenolic compounds, epicatechin, chlorogenic acid and tannin increases with the increase of temperature and storage time. The polyphenols degraded quickly during the initial period of storage and then it slowed down. The addition of ascorbic acid to the juice can inhibit the oxidation and polymerisation of phenolic compounds to avoid the formation of new small insoluble particles during the storage, and the efficacy of inhibiting between adding 0.024% or 0.006% (w/w) ascorbic acid is not remarkably different.