Studies on the Quality Changes of Mixed Fruit and Vegetable Juices as Influenced by Processing Conditions during Storage
Physicochemical properties and microbiological quality chanties were investigated on mixed fruit and vegetable juices (apple, carrot and cucumber) stored at 4 without pasteurization(NT), with light piasteurization (LP; 66, 10 sec) and with full pasteurization(FP; 90, 60 sec). Effects of ultrafiltration (UF) on the changes during storage were also examined. pH, viscosity, a-value and b-value remained relatively constant and all samples revealed Newtonian characterisitics. Total acidity and turbidity tended to increase slightly; however, total vitamin C content and L-value slowly decreased during storage up to about 2 months. During the first 4 weeks storage, soluble solids content slowly increased and then decreased. Mold and Yeast and Bacteria were not detected in LP, UP and UF treated samples during storage studied; however, E. coli were detected after 24 days storage. No distinctive storage effects were found among samples prepared; however, ultrafiltration had a considerable effect on the color and soluble solids content of mixed fruit and vegetable juice.