The purposes of this study was to investigate the effect of high pressure processing (HPP) on a sterilization and microbiological shelf-life of commercial beef patties by varying the pressure level (200, 300, 400, and 500 MPa), treatment time (0-10 min), and storage period (0-16 day at 4oC). The HPP treatment of 200 MPa were ineffective, however the treatment of 300, 400, and 500 MPa reduced the bacterial count by 0.61-1.16, 1.11-1.69, and 2.73-3.86 log (CFU/g), respectively. During 16 days of storage, the viable cell numbers in beef patties treated with 400 and 500 MPa were substantially lower than those in the non-treated control. The control count reached 6.6 log CFU/g after 16 days at 4oC, but after the same storage time, the counts in HPP-treated samples of 400 and 500 MPa were 4.7 and 3.1 log CFU/g, respectively. After an HPP treatment of 200-500 MPa, the pH values were approximately 5.83-6.28. During the 16 days of storage, the pH values in the samples of 400-500 MPa were maintained at initial levels throughout the storage period, regardless of treatment time for HPP.

Abstract
 Introduction
 Materials and Methods
  Sample preparation
  High pressure processing treatment
  pH
  Microbial analysis
 Results and Discussion
  Microbial inactivation in beef patties by HPP
  Microbial shelf-life in beef patties by HPP
  pH Changes during storage
 Summary
 References

• Chan-Ick Cheigh(Department of Food and Food Service Industry, Kyungpook National University)
• You-Lee Kang(Department of Food Science and Engineering, Ewha Womans University)
• Myong-Soo Chung(Department of Food Science and Engineering, Ewha Womans University) Corresponding author