Growth of Microorganisms in Chilled Orange Juice

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Abstract
Growth of lactic acid bacteria and yeasts in chilled orange juice was investigated. Three suspensions were prepared, each consisting of four strains of Lactobacillus, four of Leucomostoc, and four of yeast. Each composite suspension was inoculated into a series of bottles containing sterile prechilled orange juice to obtain a final concentration of 1,100, and 1,000 organisms/ml. Samples were stored at 35, 40, 45, and 50 F (1.7, 4.5, 7.2, and 10 C), and were plated periodically throughout the test period. Yeasts grew at all temperatures investigated, their rates of growth increasing with the temperature. Lactobacillus organisms grew at 50 F but not at 45 F or below, Leuconostoc strains did not grow at 35 F, but grew slowly at 40 F, and rapidly at 45 F and 50 F. Fermentation by yeasts, depending on the level of inoculation, occurred in 1 week or less at 50 F and in 1 to 2 weeks at 45 F. At 35 and 40 F it occurred in 3 weeks but was satisfactory at 35 F for the lowest level of inoculation. Spoilage from growth of Lactobacillus was detected between 1 and 2 weeks at 50 F. It did not occur at 45 F or below. Leuconostoc required 13 days to 5 weeks at 40, 45, and 50 F. Spoilage did not occur at 35 F. Shelf life of chilled orange juice is dependent upon the initial microbial population at time of packaging and temperature maintained until it reaches the consumer.

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