## 1 Introduction  
Cold atmospheric plasma (CAP), which, in the past, has mainly been used in the medical field [1; 2], has recently drawn considerable attention as a novel non-thermal technology for food product decontamination [3]. Besides the non-thermal nature of plasma, additional positive features of this technology rely on the fact that it is a dry technology, environmentally friendly, and, in most cases, represents a cost-efficient solution that can supplement or replace other technologies. CAP has shown promising results in terms of decontamination of various microorganisms [4], models, and mycotoxins [5], and for its potential to inactivate viruses [4] in food products. Anotherimportant application of CAP in foods is the partial inactivation of food enzymes that may have positive effects on products' shelf-life [6]. Despite the high potentiality, there are still many aspects about CAP technology that need to be addressed. Firstly, there are currently some practical limitations for the scaling-up of the equipment, starting from the standardization of plasma analytical techniques, safety measures for operators and the environment, to the design of equipment which are able to process large amounts of product in a continuous way [7]. Moreover, there are still aspects--particularly regarding food quality, functional characteristics, and potential toxicity of treated products--that are unknown or that need clarification. The European Food Safety Authority (EFSA) requires a scientific assessment to be done prior to authorization to ensure the novel technologies' safety. Currently, uncertainty remains in the European Commission's (EC) regulatory approval process for CAP technologies due to the lack of scientific data and ambiguous statements within the evaluation criteria (e.g., \"risk to public health\", \"nutritionally disadvantageous\", and \"not misleading to the consumer\"). With regard to the nutritional properties, few studies have investigated the CAP's effect on bioactive compounds of fruit and vegetable products. [PERSON] et al. [8; 9; 10] observed a partial oxidation of phenolic components in green leafy vegetables, although mitigation by the matrix effect compared to treatment of pure components was found. On the other hand, only a slight decrease in the total phenolic content and antioxidant activity of apple slices was observed [11]. Vitamin C was found to be only slightly affected by plasma exposure in kiwifruit [12] and various vegetable slices [13]. Thus, it appears that the degradation of bioactive components is strictly dependent on the matrix. However, studying the effect of direct plasma treatment on fruit juice (chokeberry, sour cherry, and pomegranate) using a plasma jet device with pure Argon, an increase of specific classes of polyphenols (anthocyanins and phenolic acids) was found at the shortest treatment time (3 to 4 min) [14; 15; 16]. According to these authors, the observed increase was caused by increased extractability due to disruption of the cell membrane's integrity, promoted by plasma-reactive species. The increase of secondary metabolites, such as flavonoid glycosides in plant tissue was also observed by [PERSON] et al. [17] after the exposure of pea seedlings to plasma. This result was attributed to a response mechanism of the tissue in terms of photosynthetic activity, and of the response metabolism against oxidative stress due to UV exposure. In a previous study [11], we demonstrated that a 15 + 15 min treatment caused only a slight reduction of polyphenols content and antioxidant activity on fresh-cut apples, which did not seem to interfere with the physiological responses for moderating the oxidative stress of cells loaded with the plasma-treated apple extracts. The reduction of phenolic content was probably due to oxidation promoted by plasma-active particles and radicals; nevertheless, the response of living tissue to plasma exposure may be more complex and dependent on treatment time.