Antimicrobial stability of grape seed extract (ActiVinTM), pine bark extract (Pycnogenol®), and oleoresin rosemary (Herbalox®) on the growth of Aeromonas hydrophila was investigated in cooked ground beef. When compared to the control, the populations of A. hydrophila were most effectively reduced by 4.06 log CFU/g for 1% Pycnogenol® added after cooking at 10 days of refrigerated storage, followed by 3.06 log CFU/g for 1% Pycnogenol® added before cooking and 1.36 log CFU/g for ActiVinTM. Bacteriostatic and bactericidal activities were observed for Pycnogenol® added before and after cooking, respectively. Pycnogenol® consists of heat-labile and heat-stable compounds. ActiVinTM and Pycnogenol® could be considered for use as multifunctional preservatives in meat and meat products.

Introduction
 Materials and Methods
  Plant extracts
  Bacterial culture
  Experimental design
  Sample preparation
  Microbiological analysis
  Inhibitory kinetics
  Statistical analysis
 Results and Discussion
  Antimicrobial effect of plant extracts against A.hydrophila on cooked beef
  Changes in pH values in cooked ground treated withplant extracts
  Inhibitory kinetics of plant extracts against A.hydrophila on cooked beef
 Acknowledgement
 References

• Hua Xu(Division of Biomaterials Engineering, Kangwon National University)
• Juhee Ahn(Division of Biomaterials Engineering, Kangwon National University, Institute of Bioscience & Biotechnology, Kangwon National University) Correspondence
• Azlin Mustapha(Division of Food Systems and Bioengineering, University of Missouri)