THE EFFECT OF CINNAMON AND GUAR GUM ON BACILLUS CEREUS POPULATION IN MILK S. GULER 1 and M. SEKER 1,2,3 1 Department of Biology 2 Section of Food Technology in Department of Chemical Engineering Gebze Institute of Technology Kocaeli, 41400, Turkey Accepted for Publication March 3, 2009 ABSTRACT Milk was inoculated with Bacillus cereus and the effect of cinnamon and guar gum on B. cereus counts in ultra high-temperature milk was examined by storing samples at 4 and 25C and determining microbial counts as total bacteria by plate count agar at 0, 7, 14 and 28 days. Cinnamon with or without guar gum did not significantly affect B. cereus count at 4C, but it reduced B. cereus counts of milk compared with B. cereus counts of control milk at 25C. Increasing cinnamon concentration from 0.5 to 1% increased antimicrobial effect at the starting of storage but did not affect final B. cereus count. Cinnamon shows antimicrobial activity with their essential oils penetrating through food medium to the microbial cell so the viscosity of food medium caused by stabilizers is a factor that can affect the diffusion of antimicrobial agents through medium to microorganisms and was determined by rotational viscometer. The viscosity of milk with guar gum (0.5%) was found higher than the viscosity of milk that was not including guar gum, but at the end of 28 days the B. cereus counts of milk with guar gum and cinnamon were not higher than the B. cereus counts of milk with cinnamon alone at 25C. PRACTICAL APPLICATIONS Naturally occurring food grade cinnamon with antimicrobial properties can reduce Bacillus cereus count of flavored milk like chocolate milk stored at room temperature and then allows flexibility against storage of flavored milk. As cinnamon acts as the antimicrobial agent alone, it can also be added into 3 Corresponding author. TEL: +90-262-2110; FAX: +90-262-653-8490; EMAIL: mseker@gyte.edu.tr Journal of Food Processing and Preservation 33 (2009) 415–426. © 2009 Wiley Periodicals, Inc. 415