# Quality of Tomato Juice as Influenced by Non-Thermal Air Plasma Treatment
## 3 Results and Discussion
### Effect of CAP on Physicochemical Properties
This compound is absorbed to the greatest extent from preserves, including juices. Lycopene in improperly processed tomato products can be quite unstable. The main causes of lycopene destruction at higher temperatures are isomerization and oxidation. Additionally, light, temperature, and storage time may change the impact rates of these two processes on lycopene content in tomato products. However, mild thermal treatment causes increased solubility and better absorption of lycopene without lowering its antioxidant potential. A technology, which meets the requirements of non-thermal methods and is of interest to the food industry is the low-temperature (cold) plasma treatment. The present study has shown lycopene content of 66.70 and 65.00 mg/100 g on days 1 and 3 of refrigerated storage of the tomato juice, respectively. These values were not statistically different (\(p<0.05\)) from those obtained for the juice treated with cold plasma for 30 to 600 s. In turn, the lycopene content in the control juice on experiment day 5 decreased by approximately 6%, compared with the value recorded on day 1. The cold-plasma-treated tomato juices were characterized by unchanged content of this valuable pigment throughout the storage period (Table 1). Some previous reports also demonstrated that the lycopene content increased significantly in samples subjected to High-Voltage Electric Field Cold Plasma (HVCP) using Dielectric Barrier Discharge (DBD) treatments or to the combined effect of HVCP and Ultra-Sonication (US), which resulted in better retention of lycopene compared to fresh untreated carrot juice samples [24; 25]. In a study conducted by [PERSON] et al. [26], seriguela juice was subjected to the plasma treatment using a glow discharge plasma generator (with nitrogen as the process gas). The lycopene content was found to increase in most of the experimental assays. Furthermore, the prominent increase in the content of carotenoid pigments is also in agreement with previous studies, in which the effect of CAP was observed in the acerola juice [27]. The better retention of lycopene during processing is mainly related to the conversion of the trans-isomer to the more bioavailable form (cis-isomer) [28]. Tomato juice contains vitamin C, which has the ability to deactivate peroxide radicals generated both during the preparation of food and as a result of metabolic processes in the organism. The content of ascorbic acid in the analyzed tomato juices ranged from 266.40 mg/100 g to 277.45 mg/100 g. The greatest losses of this compound during storage were recorded in the control sample. After five days, the content of vitamin C was approximately 17% lower than in the juice sample analyzed on day 1. These losses in the cold-plasma-treated juices were substantially lower (approximately 2-3% between days 1 and 10 of the experiment). Ascorbic acid was not significantly destroyed by the cold plasma effect on the tomato juice; however, the content of vitamin C on the first day of storage was statistically significantly lower in the cold-plasma-treated juices than in the control sample. However, these were small differences (up to 2%). [PERSON] et al. [29] examined the physicochemical properties of cold-plasma-treated fruits and vegetables and reported only a slight decrease in vitamin C content (less than 4%). These losses were explained by the authors by the oxidative effect of cold plasma and the potential vitamin C degradation through UV radiation generated by the plasma. [PERSON] et al. [30] assessed the effect of cold plasma on the quality of blueberry juice. The authors used different treatment times (from 3 to 6 min) and suggested application of a shorter duration of cold plasma exposure in order to protect vitamin C (Table 1). Some authors noted an increase in vitamin C content in fruits and fruit juices caused by the action of cold plasma [31; 32]. The oxidized form of ascorbic acid is dehydroroscopic acid, which is formed in the reaction with hydrogen, superoxide, hydrogen peroxide, or tocopherooxyl radical.