Abstract: In order to obtain the optimal sterilization conditions for fresh beef with a cold plasma system, where beef color is not significantly impacted, the sterilization efficiency and redness (a*) value were optimized as a function of voltage, treatment time and O2 percentage using a combination of one-factor-at-a-time method and response surface methodology with a Box-Behnken design. A quadratic polynomial regression equation to predict the two response variables was fitted. The results showed that cold plasma could effectively reduce the total viable count of beef, and a voltage of 72 kV, a processing time of 86 s and an atmosphere consisting of 35% O2, 35% CO2 and 30% N2 were found to be the optimal conditions to obtain a higher sterilization efficiency of 93.75%, agreeing with the predicted value (94.04%). The optimization model proposed in this study can provide a useful guideline for practical application of cold plasma as a sterilization technology.

Key words: cold plasma, beef, sterilization, a* value, response surface methodology