## 3 Results
### Ascorbic Acid Content in Analysed Vegetable Juices
#### 3.2.2 Ascorbic Acid Content in Analysed Vegetable Juices in Plastic Containers
After day 7, the decline in vitamin C value in the plastic container was 3.73% higher than in the glass container. The value of vitamin C in the red pepper juice at the refrigerator temperature (t\({}_{1}\) = 4 \({}^{\circ}\)C) in containers made of plastic decreased from 0.65% to 10.10% (for 7 days) (Figure 4d). The amount of vitamin C declined as the period of storage grew. The decrease in vitamin C content in the plastic containers at room temperature (t\({}_{2}\) = 23 \({}^{\circ}\)C) and at freezing temperature  
Figure 4: The concentration of vitamin C in vegetable juices in selected temperatures in plastic packaging materials for tomato (**a**), carrot (**b**), salad cucumber (**c**), red pepper (**d**), white pepper (**e**), and white cabbage (**f**). (t\({}_{3}=-18\)\({}^{\circ}\)C) for 7 days was almost the same as at t\({}_{1}\). The red pepper juice's vitamin C retention values were almost the same in the packaging materials used (glass and plastic). In the plastic containers storing the white pepper juice at t\({}_{1}=4\)\({}^{\circ}\)C, the vitamin C concentration was reduced (4.96%) after day 1 (Figure 4e). After 7 days, the decrease in vitamin C content in the plastic container was 1.60% larger than in the glass container. At t\({}_{2}=23\)\({}^{\circ}\)C throughout storage, the decrease in the vitamin C value in the plastic packaging was as follows: day 1: 3.60%; day 2: 5.12%; day 3: 8.80%; day 7: 11.84% (Figure 4e). The decrease after day 7 was 1.92% higher in plastic packaging than in glass packaging. After the first day of the storage of the white pepper juice in plastic containers at t\({}_{3}\) (\(-18\)\({}^{\circ}\)C), the loss of vitamin C was 5.20% of the original value (Figure 4e). On the second and seventh days of storage, the vitamin C values were the same in both types of containers. Following the first day of preservation of the white cabbage juice at refrigeration temperature (t\({}_{1}=4\)\({}^{\circ}\)C), a significant diminution was analysed in the juice stored in the packaging made of plastic material (21.74%) (Figure 4f). The percentage reductions in vitamin C in plastic containers over time were 26.96% to 39.13% (for 7 days). At t\({}_{2}=23\)\({}^{\circ}\)C, the storage of the white cabbage juice in plastic showed lower vitamin C degradation after the first day of storage at t\({}_{1}\). Subsequently, the degradation rate of vitamin C in the juice kept in a plastic container increased by 4.35% on day 2, 1.74% on day 3, and 0.87% after 7 days compared with the reduction in the juice stored in glass containers. The loss of vitamin C content in the cabbage juice stored in the plastic container at temperature t\({}_{3}\) (\(-18\)\({}^{\circ}\)C) was from the first day: 23.91% to the seventh day: 47.83%. Our analyses show that the decreased temperature of storage resulted in greater vitamin C preservation. The analyses (Figure 4a-f) show the effect of different variables (temperature, storage time, packaging material) on the vitamin C content of vegetable juices. The comparison shows that the storage of the vegetable juices at t\({}_{1}=4\)\({}^{\circ}\)C in plastic packaging resulted in a decrease in vitamin C of 0.65-21.74% and 5.08-26.96% over 24 and 48 h, respectively; after 3 days, the decrease was 6.56-34.78% of the original value. Over 21 days, the lowest losses of vitamin C were recorded in the red pepper juice and the highest losses in the carrot juice. These differences in the oxidative activity of vitamin C can be attributed to the different cellular structures, mechanical damage during harvesting, enzyme (ascorbate oxidase), and sulfhydryl group content, as well as the existence of catalysts such as Fe\({}^{3+}\) and Cu\({}^{2+}\). Minimal changes were observed in samples stored in a refrigerator (\(4\)\({}^{\circ}\)C).