## 3 Results
### Ascorbic Acid Content in Analysed Vegetable Juices
#### 3.2.2 Ascorbic Acid Content in Analysed Vegetable Juices in Plastic Containers  
Different factors such as storage time, temperature, and packaging material may affect the vitamin C content of vegetable juices. The changes that may occur, in addition to those related to nutritional value and safety, are important for the consumer. After one day, the vitamin C content of the tomato juice stored in plastic containers at t\({}_{1}\) = 4 \({}^{\circ}\)C decreased by a greater percentage than when stored in glass containers. In the subsequent days, the decline accelerated (from 5.77% to 8.65% in seven days) (Figure 4a). After three weeks of storage at t\({}_{1}\) = 4 \({}^{\circ}\)C in a plastic container, the tomato juice's ascorbic acid content decreased to 57.69%. On the first day at temperature t\({}_{2}\) (23 \({}^{\circ}\)C), there was an equal decrease in vitamin C (6.73%) in both plastic and glass-stored juices. One week at ambient temperature t\({}_{2}\) (23 \({}^{\circ}\)C) in plastic containers decreased the vitamin C concentration in tomato juice by 35.10%. According to the analyses of [PERSON] and [PERSON] [51], heating has a significant influence on the vitamin C concentration of tomato juice; the concentration decreases with increasing temperature and time. Figure 4a demonstrates that when the tomato juice was frozen at t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C in a plastic container, the vitamin C concentration decreased more than in a glass container. The concentration of vitamin C in the tomato juice stored in plastic containers at subfreezing temperatures ranged from 2.89% to 31.73%. The assimilation of reactive oxygen species by tomato juice at low temperatures indicates a complex network of molecules and enzymes that are part of the antioxidant mechanism and correlate with fruit shelf life. The loss of the vitamin C content of the carrot juice preserved in plastic packaging in the refrigerator (t\({}_{1}\) = 4 \({}^{\circ}\)C) decreased from 11.99% (after the first day) to 45.13% (after the seventh day) (Figure 4b). After 21 days at t\({}_{1}\) = 4 \({}^{\circ}\)C in a plastic container, ascorbic acid levels dropped to 56.52%. The vitamin C concentration decreased as follows when stored at room temperature (t\({}_{2}\) = 23 \({}^{\circ}\)C) in plastic containers: day 1: 13.86%; day 2: 25.09% (Figure 4b). After three days, the plastic concentration decreased 6.5% more in plastic than in glass containers. In seven days, the vitamin C concentration in the plastic material decreased by 39.14%. The results indicate that vitamin C loss increases with increasing temperature. As of the first day of storage in plastic containers in the freezer at t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C, the vitamin C levels decreased threefold more than in glass containers (Figure 4b). The loss of vitamin C in the plastic containers ranged from 36.33% (first day) to 49.44% (seventh day). The preservation of vitamin C in carrot juice in glass containers at freezing temperatures was significantly superior to that of plastic containers. The cucumber juice stored in a refrigerator (t\({}_{1}\) = 4 \({}^{\circ}\)C) in plastic containers had less vitamin C concentration after 1 day than juice stored in glass containers (Figure 4c). The vitamin C value of the plastic containers decreased rapidly from day 1 (from 7.46% to 4.93%). The loss in the plastic containers was 4.487% larger than in the glass containers after one week of storage (14.93%). The values of vitamin C in the cucumber juice at room temperature (t\({}_{2}\) = 23 \({}^{\circ}\)C) in plastic containers were lower than in glass containers (Figure 4c). However, the cucumber juice in a plastic container had the same loss of vitamin C at 7 days as the juice in glass containers (11.94%). In plastic containers, when the cucumber juice was stored at t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C, there was a significant decline from the beginning in the vitamin C concentration on day 1 of storage (from 10.45% to 19.40%) (Figure 4c).