# Bioactive Vitamin C Content from Natural Selected Fruit Juices
## 3 Results and Discussion
### Correlation between Vitamin C Content and Storage Conditions
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Juices** & \multicolumn{3}{c}{**Glass Containers**} & \multicolumn{3}{c}{**Plastic Containers**} \\ \hline  & **t1 = 4 \({}^{\circ}\)C** & **t2 = 23 \({}^{\circ}\)C** & **t3 = \(-\)18 \({}^{\circ}\)C** & **t1 = 4 \({}^{\circ}\)C** & **t2 = 23 \({}^{\circ}\)C** & **t3 = \(-\)18 \({}^{\circ}\)C** \\ \hline Grapefruit & \(-\)0.952 & \(-\)0.952 & \(-\)0.898 & \(-\)0.944 & \(-\)0.913 & \(-\)0.871 \\ Mandarin-clementine & \(-\)0.807 & \(-\)0.864 & \(-\)0.842 & \(-\)0.789 & \(-\)0.902 & \(-\)0.830 \\ Late Peach & \(-\)0.935 & \(-\)0.766 & \(-\)0.919 & \(-\)0.882 & \(-\)0.855 & \(-\)0.920 \\ Winter Apple & \(-\)0.874 & \(-\)0.805 & \(-\)0.758 & \(-\)0.724 & \(-\)0.741 & \(-\)0.654 \\ Winter Pear & \(-\)0.957 & \(-\)0.832 & \(-\)0.813 & \(-\)0.688 & \(-\)0.744 & \(-\)0.782 \\ Autumn Plum & \(-\)0.945 & \(-\)0.834 & \(-\)0.877 & \(-\)0.608 & \(-\)0.764 & \(-\)0.760 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The correlation coefficients between the amount of vitamin C (mg/100 g) present in fruit juices kept in glass and plastic containers at various temperatures and for varying lengths of time. In fruit juices stored in glass and plastic containers, the content of vitamin C gradually decreases. The values of the decrease in vitamin C content in fruit juices were calculated based on the measured concentration values and linear regression equations. The correlation factor R\({}^{2}\) is generally considered to be the degree of fit of the experimental data to the chosen model. From the data in Table 3, it can be seen that in some cases, the R\({}^{2}\) is more or less close to one, and in other cases, it is far from it. To simplify the classification of the data in Table 3, the threshold correlation parameter R\({}^{2}\geq 0.71\) as satisfactory and R\({}^{2}\) (0.00-0.70) as quasi-unsatisfactory. Based on the data obtained at different temperatures (t\({}_{1}\) = 4 \({}^{\circ}\)C, t\({}_{2}\) = 23 \({}^{\circ}\)C, t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C) in Table 3, the regression equations for the decrease in the vitamin C concentration values (in mg) in fruit per 100 g of fruit juice over a period of 7 days are shown. The slope of the regression line was interpreted as an estimation of the rate of vitamin C loss at this storage condition. Variability in the vitamin C (ascorbic acid) content of citrus fruit and their products is influenced by variety, cultural practice, maturity, climate, fruit quality, fresh fruit handling, processing factors, packaging, and storage conditions [53; 95], and certainly applies to home-grown fruit too. Taking into account overall averages, [PERSON] [53] pointed out that the citrus juice richest in vitamin C is orange juice, followed by grapefruit, lemon, and mandarin. Analysed results agreed with the statement of [PERSON] [53], in that the vitamin C content of citrus juices from grapefruit was higher (34.50 mg/100 g) than that of mandarin (23.00 mg/100 g). The values for citrus juice of grapefruit and mandarin were within the interval reported by [PERSON] [53]. The subsequent content of vitamin C was the second highest in mandarin-clementine juice, which agreed with the study of [PERSON] et al. [45], who reported that \"Mediterranean mandarin and clementine (C_Citrus reticulata Blanco_) reach the highest values of vitamin C\".