Atmospheric pressure cold plasma technology is an emerging nonthermal food technology for microbiological decontamination of food and bio-materials. This study demonstrates the applicability of in-package cold plasma technology as a novel means to inactivation of enzymes. The kinetics of inactivation of tomato peroxidase as a model enzyme was studied at 30, 40 and 50 kV, for up to 5’ of atmospheric air dielectric barrier discharge plasma treatments. The enzyme activity was found to decrease with both treatment time and voltage, the former variable exhibiting a more pronounced effect. Kinetic models viz. first-order, Weibull and logistic models were fitted to the experimentally observed data to numerate the model parameters. The enzyme inactivation kinetics was found to be best described the sigmoidal logistic function. Industrial Relevance In-package cold plasma processing is a novel and innovative approach for the decontamination of foods with potential industrial application. This paper provides evidence for reduction of tomato peroxidase activity using cold plasma from a dielectric barrier discharge. It also demonstrates that the sigmoidal shaped logistic model adequately describes the enzymatic inhibition. The work described in this research is relevant to the processing of fruits, vegetables and their products, wherein enzyme activity leads to quality deterioration.