Studies On Microbiological And Physico- Chemical Analyses Of Commercially And Laboratory Prepared Orange Juices

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 shelf- life 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,