89D-7 |
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A. KHACHATRYAN1, M. E. Janes1, W. Prinyawiwatkul1, H. K. No2, and A. Abushelaibi1. (1) Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Baton Rouge, LA 70803-4200, (2) Dept. of Food Science & Technology, Catholic Univ. of Daegu, Hayang, 712-702, South Korea Microorganisms can attach to solid surfaces and form microcolonies or biofilms on food contact equipment surfaces. Listeria monocytogenes can survive for prolonged periods on stainless steel and rubber materials commonly used in food processing plants. Routine chemical cleaning, accompanied by manual/mechanical scrubbing, of food contact surfaces is an effective way to minimize biofilms. This study was conducted to evaluate efficacy of chitosan against Listeria monocytogenes (LM) and Escherichia coli 0157:H7 (EC) adhered to stainless steel, rubber, and glass surfaces. Both 0.5% and 1% chitosan solutions (in 1% acetic acid) were prepared from high (1,100 kDa, HMw) and/or low (470 kDa, LMw) molecular weight chitosan, and the pH of the solutions was adjusted to 5.6. 100μl of overnight cultures of LM and EC was separately inoculated onto each of three surfaces and incubated at 37oC for 1 hr. Each inoculated surface was treated with chitosan, acetic acid (as control) or PBS (as control) solution for 15 min, then plated onto Oxford and SMAC agar plates, incubated at 37oC for 48 hr, and CFU/ml was determined. Triplicate experiments were conducted. Data were statistically analyzed (alpha=0.05). Regardless of surface type, EC counts were reduced by ca. 2 log CFU/ml with the highest reduction observed on the surface treated with 1% HMw chitosan. LMw (0.5 and 1%) and HMw (1%) chitosans were more effective against EC on the glass surface than on the stainless steel surface. For stainless steel surface, 0.5% LMw chitosan was most effective against LM, with 2.5 log CFU/ml reduction. For both 0.5% and 1.0% concentrations, HMw chitosan was more effective against EC than LM on the stainless steel surface. Our study showed that chitosan has the ability against LM and EC adhered to different surfaces. Chitosan may serve as an antimicrobial cleaning agent for food contact surfaces in food processing plants.
Session 89D, Food Microbiology: Antimicrobial effects on foodborne microorganisms
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |