# Impact of Atmospheric Pressure Microwave Plasma Treatment on Quality of Selected Spices
## 1 Introduction  
The food industry can be characterized as a very competitive branch of the economy. This fact, together with the increasing knowledge of consumers, who pay more attention to their nutrition and care greatly about the environment, stimulates producers and scientists to develop new food processing and preservation technologies. The main aim of food processing is to deliver safe food that can be characterized by good quality. Within the factors that can be considered a hazard, microbial growth can be distinguished. Conventionally, inactivation of microbiota can be achieved by thermal methods such as pasteurization or sterilization [1; 2; 3; 4]. Although these techniques are effective considering their lethal effect on microorganisms' growth, they also cause degradation of many thermolabile compounds, with nutritional activity being of paramount importance [5; 6]. Therefore, new technologies start to play very important roles, since they allow reduction of microbial contamination and, at the same time, they can maintain the quality of processed food. Among these emerging methods, a few need to bedistinguished such as pulsed electric field, ultrasound, high hydrostatic pressure and pulsed light cold plasma [7; 8; 9; 10]. Moreover, cold plasma is also considered a very promising method that can achieve the abovementioned technological effects with minimal impact on food quality [11].  
In general, nonequilibrium plasmas under atmospheric pressure have been used for various purposes [11; 12; 13; 14; 15; 16; 17] such as material processing (e.g., etching, deposition, polymer surface activation), food processing, surface decontamination (e.g., sterilization of surgical instruments) and decomposition of gases and liquids (e.g., production of valuable chemicals, environmental applications).  
Atmospheric plasma can be generated using different methods. For instance, it can be generated using microwaves [18] or a dielectric barrier discharge (DBD) system [19]. The utilization of microwaves for generation of plasma is becoming increasingly popular. The microwave plasma is characterized by a wide range of temperatures. Applications of atmospheric pressure microwave plasma are very wide. Such plasmas can be used for gas processing [20; 21], surface modification [22] or for biomedical decontamination [14; 23; 24; 25]. Because of the specific determinants of microwave generated plasma, especially the fact that it can operate under atmospheric pressure, it can be used in the food industry. Publications show that treatment performed with this plasma can be used in decontamination [26], degradation of mycotoxins [27] and indirect treatment of meat [28] and black pepper [29].  
In the case of food processing, plasma is generated in a discharge volume and makes contact with the treated food surface. Fast electrons, ions and free radicals, as well as electromagnetic radiation in the UV/VIS spectrum, are then transferred to the plasma-surface interface where they initiate basic processes such as etching, recombination, de-excitation and re-emission from solids [13]. As a result, plasma treatment can decontaminate food surfaces and change their physicochemical properties, leading to extended food shelf life.  
The aim of this work was to examine the usefulness of atmospheric pressure argon microwave plasma, in the unique form of a plasma sheet, on the decontamination of selected spices (pepper seeds, juniper and allspices berries), and to evaluate the impact of such treatment on the physicochemical properties of used materials.