Abstract

Black mulberry juice gains popularity based on the high antioxidant content of it. However, acid adapted pathogens in fresh fruit juice are strong threats for food safety. The survival and growth patterns of Escherichia coli O157:H7 (932) and Salmonella Typhimurium (NRRL B 4420) in black mulberry (Morus nigra) juice were determined in this study. The mulberry juices were differently concentrated (100, 50, 10 and 1%) and have different pH values (3.70, 4.34, 4.80, 4.89 and 7.00) were used as test medium. Acid adapted and also non acid adapted E. coli O157:H7 and S. Typhimurium were used as test microorganisms. All the juice samples were inoculated (6 log-cfu/ml) with the test cultures separately and incubated at two different temperatures (4 and 37°C) during 7 days. The survival and growth pattern of the test cultures were periodically determined during incubation by enumeration. It was detected that the test results of all the test microorganisms were similar at 37°C. However, S. Typhimurium was more resistant thanE. coli O157:H7 at 4°C. None of the microorganisms (acid adapted and non acid adapted) were detected at the end of 7 days incubation. The results were generally correlated with the concentration of the black mulberry juice as well as the incubation temperature and time.

Key words: Black mulberry, juice, Escherichia coli O157:H7, Salmonella Typhimurium, survival pattern.