Analytical Assessment of Vitamin C Stability in Citrus Fruit Juices Under Different Storage Conditions

Vitamin C (ascorbic acid) is an essential water-soluble antioxidant widely distributed in citrus fruits and fruit-derived products. Due to its liability to degradation during storage, the preservation of vitamin C content is an important factor affecting the nutritional quality of fruit juices. The present study aimed to determine the vitamin C content in different citrus fruit juices and to evaluate the influence of storage conditions on its stability over time. Fresh juices obtained from Albanian and imported lemons, oranges, mandarins, and imported citron were analysed using iodometric titration method. Vitamin C concentrations were determined immediately after juice extraction and after storage under ambient conditions (22°C) and refrigerated conditions (4°C) for 0, 24 and 48 hours (the 1^st, 2^nd and 3^rd day). The results revealed considerable variation in the initial vitamin C content among the analysed fruits. Imported citron exhibited the highest vitamin C concentration (62.77 mg), followed by Albanian orange (54.03 mg) and imported orange (46.64 mg), whereas imported mandarin presented the lowest concentration (3.97 mg). A gradual decrease in vitamin C content was observed in all samples during storage, with significantly greater losses occurring at ambient temperature than under refrigeration. After 48 hours of storage, Albanian lemon juice showed the greatest reduction in vitamin C concentration at room temperature, while Albanian orange juice demonstrated the highest stability. Refrigerated storage consistently preserved higher vitamin C levels in all fruit juices compared with ambient storage. These findings confirm that both storage duration and temperature significantly influence the retention of ascorbic acid in citrus juices. The study highlights the importance of refrigerated storage as an effective strategy for minimizing vitamin C degradation and maintaining the nutritional quality of fruit juices. Furthermore, the results support the applicability of iodometric titration as a simple, reliable, and cost-effective method for routine determination of vitamin C in food samples.