# Bioactive Vitamin C Content from Natural Selected Fruit Juices
## 3 Results and Discussion
### Vitamin C Content in Juices Stored in Glasses Containers
The contents of vitamin C in mandarin-clementine juice stored in a glass container in a freezer (t\({}_{3}=-\)18 \({}^{\circ}\)C) obtained by analysis are shown in Table 1. Recorded percentage changes in vitamin C content in mandarin juice in glass containers were as follows: 1 st day: \(-\)19.57%; 2 nd day: \(-\)26.09%; 3 rd day: \(-\)41.30%; 7 th day: \(-\)48.48%. The values of vitamin C content found in citrus juices agree with the results obtained by [PERSON] [53]. However, the vitamin C content was much lower in the other fruit juices analysed. The juice from late peach, stored in the refrigerator (t\({}_{1}\) = 4 \({}^{\circ}\)C) in glass packaging, had a lower vitamin C content than citrus fruit (3-4 times). The decrease of vitamin C in glass packaging was as follows: 1 st day: \(-\)1.18%; 2 nd day: \(-\)2.94%; 3 rd day: \(-\)3.53%; 7 th day: \(-\)5.88% (Table 1). [PERSON] et al. [33] reported that the storage environment of fresh fruit juice could significantly affect vitamin C content. For room temperature (t\({}_{2}\) = 23 \({}^{\circ}\)C) in peach juice stored in glass packaging materials, the following reduction in vitamin C content was analysed: 1 st day: \(-\)8.24%; 2 nd day: \(-\)10.59%; 3 rd day: \(-\)12.94%; 7 th day: \(-\)15.88%. In glass containers, the decrease in vitamin C content when storing peach juice at t\({}_{3}=-\)18 \({}^{\circ}\)C was slow, with the same value of vitamin C on the 2 nd and 3 rd day of storage (Table 1). Thus, there was no loss after the 3 rd day of storage (1 st day: \(-\)4.12%; 2 nd day: \(-\)7.06%; 3 rd day: \(-\)7.06%; 7 th day: \(-\)15.29%). [PERSON] [44] reported that vitamin C degrades immediately after harvesting. However, it is still degraded during long-term storage, and the degradation persists even with prolonged storage of frozen products [44]. The vitamin C content of the winter apple juice at storage temperature t\({}_{1}\) = 4 \({}^{\circ}\)C decreased in the glass packaging as follows: 1 st day: \(-\)4.55%; 2 nd day: \(-\)3.41%; 3 rd day: \(-\)11.36%; 7 th day: \(-\)18.41% (Table 1). At room temperature (t\({}_{2}\) = 23 \({}^{\circ}\)C) in glass packaging material, in winter, apple juice, after the 1 st day, stored vitamin C content decreased by \(-\)4.55% and after the 2 nd day of storage, by 6.82%. The overall decrease in vitamin C after 7 days of storage was 22.05% for glass packaging. Table 1 indicates the decrease of vitamin C values when apple juice is stored in the freezer at t\({}_{3}=-\)18 \({}^{\circ}\)C in glass packaging material. The vitamin C content of apple juice at storage temperature t\({}_{3}=-\)18 \({}^{\circ}\)C in glass containers were as follows: 1 st day: \(-\)14.77%; 2 nd day: \(-\)17.05%; 3 rd day: \(-\)17.05%; 7 th day: \(-\)25.00%. Analysed results of vitamin C content in apple juice were lower at t\({}_{2}\) = 23 \({}^{\circ}\)C and t\({}_{3}=-\)18 \({}^{\circ}\)C compared to t\({}_{1}\) = 4 \({}^{\circ}\)C, which was different from the results found by [PERSON] and [PERSON] [73] and [PERSON] et al. [3]. In the studies, the authors found that, for optimal vitamin C content, it is best to use freshly harvested fruit or minimal fruit storage at room temperature and refrigerator temperature, respectively [3,73]. In the glass containers, the vitamin C content in winter pear juice stored in a refrigerator at t\({}_{1}\) = 4 \({}^{\circ}\)C decreased as follows: 1 st day: \(-\)0.75%; 2 nd day: \(-\)1.49%; 3 rd day: \(-\)2.99%; 7 th day: \(-\)2.99% (Table 1). At t\({}_{2}\) = 23 \({}^{\circ}\)C, regarding the winter pear juice, the vitamin C content decreased in the glass containers as follows: 1 st day: \(-\)2.24%; 2 nd day: \(-\)4.48%; 3 rd day: \(-\)4.48%; 7 th day: \(-\)5.97% (Table 1). Between the 2 nd and 3 rd days, there was no further decrease in vitamin C content in glass containers. Table 1 showed decreased vitamin C values when winter pear juice is stored in a freezer at t\({}_{3}=-\)18 \({}^{\circ}\)C in glass packaging materials. The vitamin C content decreased in the glass container by 1.45% on the first day of storage.