89A-34 |
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R. SUBBURATHINAM1, K. Nadarajah2, M. E. Janes2, W. Prinyawiwatkul2, and H. K. No3. (1) Dept. of Animal Science, Bharathidasan Univ., Palkalaiperur, Tiruchirappalli, 620024, India, (2) Dept. of Food Science, Louisiana State Univ. Agricultural Center, Baton Rouge, LA 70803-4200, (3) Dept. of Food Science & Technology, Catholic Univ. of Daegu, Hayang, 712-702, South Korea Increasing incidents of food-borne illnesses and unavailability of potent antimicrobial agents applicable to control food-borne pathogens prompt development of more effective antimicrobial systems. Chitosan and lactoferrin are natural antimicrobial agents, and, when combined, may provide synergistic effects against food-borne pathogens. This study was conducted to evaluate synergistic effects of crawfish chitosan and lactoferrin against Listeria monocytogenes and Escherichia coli 0157:H7. Chitosan was prepared from crawfish shell waste. Chitosan (1% w/v) in 1% acetic acid was hydrolyzed and mixed with 0.25, 0.50, 0.75, 1.0, and 2.0 % w/v lactoferrin. The chitosan-lactoferrin (CL) solution was allowed to hydrolyze overnight. Pellets of bacteria prepared from 1 mL of L. monocytogenes and E. coli 0157:H7 with 107 - 108 cfu/mL were introduced to 1 mL of CL solution and incubated at 37o C. Samples were drawn at 0, 2, 4, 8, and 24 h and plated for bacterial enumeration. Chitosan without lactoferrin (CH), lactoferrin without chitosan (LF), and phosphate buffer solution (PBS) were used as controls. Triplicate experiments were conducted. CH showed inherent antimicrobial property and caused gradual reduction of both pathogens with increased time. Compared to the controls, CL solution caused significantly more reduction in cfu/mL of L. monocytogenes and E. coli 0157:H7 than did CH or LF alone; this indicated synergistic antimicrobial effects of chitosan and lactoferrin. Increased lactoferrin concentration in CL solution caused greater reduction of bacteria counts, indicating that antimicrobial effect of CL was a function of lactoferrin concentration. CL solution with 2% lactoferrin was most effective against L. monocytogenes and E. coli 0157:H7; the cfu/mL of both pathogens reached zero within 2 h. Similar reductions (zero cfu/mL) were also observed with CL solution with 1% lactoferrin within 4 h. The study demonstrated the synergistic antimicrobial effects of crawfish chitosan and lactoferrin against L. monocytogenes and E. coli 0157:H7.
Session 89A, Aquatic Food Products: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |