STUDIES ON MICROBIOLOGICAL AND PHYSICOCHEMICAL ANALYSES OF COMMERCIALLY AND LABORATORY PREPARED ORANGE JUICES
STUDIES ON MICROBIOLOGICAL AND PHYSICOCHEMICAL ANALYSES OF COMMERCIALLY AND LABORATORY PREPARED ORANGE JUICES
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Date
2005-08
Authors
OBASI, BLESSING CHIDI
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Abstract
Microbiological and physico-chemical analyses and sensory evaluation were carried out
on commercially and freshly prepared orange juice (100%) in the laboratory and its shelflife
after the storage period of 90 days using various storage methods. At the end of the
study, the result showed that the laboratory processed orange juice in terms of the
nutritional composition when compared with the commercially processed orange juice
had a better quality considering the parameters assessed. The results of the laboratory
prepared orange juice showed that the chemically treated, pasteurized, concentrated and
carbonated orange juice had total soluble solids (TSS) ranging from 26-33 oBrix. The
vitamin C content for the untreated juice (fresh) and the commercially produced were 43
and 2.67 mg/100ml respectively. The experimental samples of chemically treated,
pasteurized, concentrated and carbonated had vitamin C content ranging from 22-29, 27-
32, 28-30 and 17-29 mg/100ml respectively. Potassium was the major mineral nutrient
which ranged from 1.44 – 2.63%. Sodium and phosphorus were found in small amounts
ranging from 0.01 -0.12 and 0.001-0.02% respectively in the orange juice. Among the
various processing methods concentrated orange juice ranked first followed by
chemically treated, pasteurized and carbonated in terms of the sensory evaluation as
assessed by the panelists. The microbiological analysis showed the total plate counts
ranged from bacteria 1.50x106 to 3.75x106 and the total yeast cell counts ranged from
1.7x106 to 4.7x106, colony forming units per ml (cfu/ml). The microorganisms isolated
and tentatively identified included the following; Escheriachia coli, Bacillus cereus,
Pseudomonas aeruginosa, yeasts and moulds which comprise Saccharomyces cerevisiae,
Saccharomyces rouxii, Sacharomyces telluris, Candida mensenterica, Rhodotorula
mucilaginosa, Brettanomyces anomalus, Aspergillus, Mycelia, Helminthosporium,
Gliocladium, Chrysosporium and Blastomyces. This study showed that the nutritional
quality of orange juice can be maintained considering the physico-chemical analysis and
that the level of microbial spoilage can be reduced to the acceptable limits if temperature
fluctuations and oxygen present in the environment of storage are controlled.
Description
Department of Microbiology Ahmadu Bello University Zaria.
Keywords
STUDIES,, MICROBIOLOGICAL,, PHYSICOCHEMICAL,, ANALYSES,, COMMERCIALLY,, LABORATORY,, PREPARED,, ORANGE JUICES