PROCYANIDIN CONTRIBUTIONS TO HAZE FORMATION IN ANAEROBICALLY PRODUCEDAPPLE JUICE

Procyanidins in apple juice and a model system were examined for their haze-forming potential. In anaerobically prepared juice, only unheate d samples stored with an air headspace formed haze. Heated juice gave an immediate increase in turbidity, but turbidity did not develop furt her on storage at 20 degrees C for 216 d. Sephadex LH-20-isoiated proc yanidins did not develop turbidity over 216 d at 20 degrees C in malat e buffer pH 3.5. Lack of headspace enhanced storage stability in all s amples tested. Light microscopy supported the above findings relative to particle development, and staining with toluidine blue provided a m ore sensitive detection of particulate. The use of toluidine blue stai ning as a predictive test for haze development is suggested. Electron microscopy of negatively stained juice and model system preparations s howed several particulate morphologies typical to each preparation. Th ese particles probably grow and aggregate to form macroscopic haze.