# Bioactive Vitamin C Content from Natural Selected Fruit Juices
## 3 Results and Discussion
### Correlation between Vitamin C Content and Storage Conditions
For the analyses of vitamin C content in fruit juices, the highest value of loss for mandarin-clementing was analysed at t\({}_{2}\) = 23 \({}^{\circ}\)C, and for winter pear fruit juice, at t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C.  
In other fruit juices, the mean value of vitamin C content at t\({}_{1}\) = 4 \({}^{\circ}\)C decreased over 24 h in the juice of grapefruit (\(-\)1.34 mg/100 g fruit juice), winter apple (\(-\)0.202 mg/100 g fruit juice), autumn plum (\(-\)0.13 mg/100 g fruit juice), and late peach (\(-\)0.12 mg/100 g fruit juice). After 24 h, the mean vitamin C content decreased in selected temperatures (t\({}_{2}\) = 23 \({}^{\circ}\)C, t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C) gradually in the juice of grapefruit (\(-\)1.66 mg/100 g fruit juice; \(-\)1.71 mg/100 g fruit juice), late peach (\(-\)0.31 mg/100 g; \(-\)0.52 mg/100 g fruit juice), winter apple (\(-\)0.259 mg/100 g fruit juice; \(-\)0.23 mg/100 g fruit juice), and autumn plum (\(-\)0.201 mg/100 g fruit juice; \(-\)0.15 mg/100 g fruit juice). Vitamin C (the sum of ascorbic and dehydroascorbic acid) is a high-temperature nutrient [96]. According to the authors [PERSON] and [PERSON] [97], high storage temperatures cause the breakdown of ascorbic acid, which is the most important factor. Comparing the different temperatures (t\({}_{1}\) = 4 \({}^{\circ}\)C, t\({}_{2}\) = 23 \({}^{\circ}\)C, t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C) at which the fruit (grapefruit, mandarin-clementing, late peach, winter apple, winter pear, autumn plum) were stored, in glass containers (Table 3), showed that the most suitable temperature for fruit juice was:  
Grapefruit and late peach: t\({}_{1}\) = 4 \({}^{\circ}\)C, followed by t\({}_{2}\) = 23 \({}^{\circ}\)C, while the greatest decrease in vitamin C content occurred at storage temperature t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C;  
Mandarin-clementing: t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C followed by t\({}_{1}\) = 4 \({}^{\circ}\)C, while the greatest decrease in vitamin C content occurred at t\({}_{2}\) = 23 \({}^{\circ}\)C;  
Winter apples, winter pears, and autumn plums: t\({}_{1}\) = 4 \({}^{\circ}\)C followed by t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C, while the greatest decrease in vitamin C content occurred at t\({}_{2}\) = 23 \({}^{\circ}\)C.  
In fruit juices stored in plastic containers, the concentration of vitamin C gradually decreases. Based on calculations from the data analysed at different temperatures (t\({}_{1}\) = 4 \({}^{\circ}\)C, t\({}_{2}\) = 23 \({}^{\circ}\)C, t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C), Table 3 summarises the linear equations for the decrease in vitamin C concentration values (in mg) in fruit per 100 g of fruit juice over 7 days. The equations show that in plastic containers at t\({}_{1}\) = 4 \({}^{\circ}\)C (t\({}_{2}\) = 23 \({}^{\circ}\)C, t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C), mandarin-clementing juice has the highest loss of vitamin C content \(-\)2.74 mg/100 g fruit juice (\(-\)2.98 mg/100 g fruit juice; \(-\)2.8 mg/100 g fruit juice) and the lowest loss of vitamin C content winter pear juice \(-\)0.106 mg/100 g of fruit juice (\(-\)0.105 mg/100 g fruit juice; \(-\)0.119 mg/100 g fruit juice). In the other fruit juices, the mean vitamin C content decreased over the period of observation at the monitored temperatures (t\({}_{1}\) = 4 \({}^{\circ}\)C, t\({}_{2}\) = 23 \({}^{\circ}\)C, t\({}_{3}\) = \(-\)18 \({}^{\circ}\)C) in grapefruit juice (\(-\)1.61 mg/100 g; \(-\)1.75 mg/100 g -1.83 mg/100 g), late peach (\(-\)0.34 mg/100 g fruit juice; \(-\)0.52 mg/100 g fruit juice; \(-\)0.12 mg/100 g fruit juice), winter apples (\(-\)0.25 mg per 100 g of fruit juice; \(-\)0.22 mg/100 g of fruit juice; \(-\)0.26 mg/100 g of fruit juice), and autumn plums (\(-\)0.16 mg/100 g of fruit juice; \(-\)0.23 mg/100 g of fruit juice; \(-\)0.17 mg/100 g of fruit juice).