TECHNOLOGICAL AND MICROBIOLOGICAL STUDIES ON SOME JUICES

Abstract

In this study, vacuum concentration (V.C.) and serum­ pulp concentration methods (S.P.) were used to produce concentrated apricot and peach juices. The juice was concentrated without any additive as control and with addition of ethylene diamine tetra-acetic acid (EDTA) and/or ascorbic acid. The concentrated juices were stored at -l2°C for nine months. Fresh and concentrated juices were chemically analyzed for some characteristics which indicate the quality of juices. Also, microbiological examination was done for fresh and concentrated juices. Furthermore, effect of adding EDTA and ascorbic acid on chemical composition and microbiological examination on concentrated apricot and peach juices were studied. Finally, sensory evaluation was done for all concentrated juices. Generally, it could be concluded that the concentrated juice produced by serum-pulp, was better than concentrated juice produced by vacuum concentration. Addition of ascorbic acid inhibited the changes in some chemical and physical characteristics, slightly better than the addition of EDTA. Both concentration methods decreased the total viable bacterial count, yeast and moulds. However, the concentrated juices produced by V.C. contained a. lower number of microorganisms than the concentrated juices produced by S.P.C. method. Addition of ascorbic acid or EDTA lead to decrease the microbiological load, but ascorbic acid was more effective. The chemical, composition and organoleptic properties of fresh carrot juice, and juice preserved by heat treatment and/or addition of benzoic acid, sorbic acid, or sodium metabisulfate, were also studied.