Manufacture of ice cream with improved microbiological safety by using gamma irradiation

Abstract

Children suffered from leukemia want to eat delicious dishes, such as cake and ice cream. However, it is very difficult to serve these foods to immune-compromised patients without application of any adequate sanitary measures. This study was conducted to evaluate application of irradiation to frozen ready-to-eat food, ice cream. Three ice creams with flavors of vanilla, chocolate and strawberry were manufactured and gamma irradiated at the absorbed doses of 1, 3, and 5 kGy at -70 degrees C. Total microflora and coliform bacteria were determined, and Listeria spp., Escherichia coli and Salmonella spp. were also tested by the use of API 20E Kit. Aerobic bacteria, yeast/mold and coliforms were contaminated in the levels of 2.3 to 3.3, 2.3 to 2.7 and 1.7 to 2.4 log CFU/g, respectively. In samples irradiated at 5 kGy, the growth of any microorganisms could not be observed. Listeria spp. and E. coli were detected at non-irradiated samples, but S. spp. was not existed. D(10) values of L. ivanovii and E. coli were 0.75 and 0.31 kGy, respectively, in ice cream. From these results, irradiation technology can reduce the risk by the food-borne pathogens of ice cream. (C) 2009 Published by Elsevier Ltd.