T. Beveridge et al., PROCYANIDIN CONTRIBUTIONS TO HAZE FORMATION IN ANAEROBICALLY PRODUCEDAPPLE JUICE, Lebensmittel-Wissenschaft + Technologie, 30(6), 1997, pp. 594-601
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.