# Bioactive Vitamin C Content from Natural Selected Fruit Juices
###### Abstract  
The content of vitamin C in fruit juices can be lowered by alterations in storage and temperature. This study compared storage circumstances (temperature, duration, and packaging type) to determine which variable had the biggest influence on changes in the vitamin C content of juices (grapefruit, mandarin, peach, apple, pear, plum). Fruit juices held in glass (plastic) containers at 4 \({}^{\circ}\)C saw vitamin C losses in the range of 0.0-10.9% (2.4-17.4%) in 24 h, 1.4-22.6% (5.2-25.3%) in 48 h, and 2.8-37.0% (6.0-39.0%) in three days. By raising the storage temperature to 23 \({}^{\circ}\)C, vitamin C losses in glass (plastic) containers were found to be 1.4-19.1% (5.2-22.2%), 2.8-20.9% (5.9-25.9%), and 4.5-43.5% (6.0-38.7%) of the value after 24 h, 48 h, and three days, respectively. When decreasing the temperature to \(-18\)\({}^{\circ}\)C in fruit juices stored in glass (plastic) containers, there were losses of vitamin C in 24 h in the range of 1.5-19.6% (3.0-20.0%), in 48 h, 4.5-26.1% (4.5-26.1%), and in three days, 6.0-43.1% (5.8-43.5%) of the value. The effect of temperature on vitamin C concentration has been proven. Fruit juice's vitamin C is more stable when kept in glass containers as opposed to plastic ones, which have a limited shelf life. asorbic acid; temperature; storage; packaging material; degradation; refrigerated juice; frozen juice +
Footnote †: journal: Applied  
The richest natural sources of ascorbic acid are fruits and vegetables, which provide more than 90% of vitamin C in the human diet [33; 34; 35]. Vitamin C (C\({}_{6}\)H\({}_{8}\)O\({}_{6}\))-ascorbate or/and ascorbic acid (Asc) is a vital water-soluble nutrient [36] that humans and other primates cannot synthesise [2; 35; 37; 38], owing to mutations in the gene that produces L-gulono-\(\gamma\)-lactone oxidase (GLO), the essential enzyme catalysing the final step of vitamin C formation [9]. Vitamin C that occurs naturally in fruit and vegetable juices is highly labile [3]. Vitamin C, as a water-soluble antioxidant [33; 34; 39], is readily oxidised by two metabolites--first to active dehydroascorbic acid [17; 40], then to diketogulonic, oxalic, and threonine acids [41]. The first reaction is reversible [17], but the following are not. Its deactivation occurs under the influence of air, light, and heat. It is susceptible to chemical and enzymatic oxidation during the processing, cooking, and storage of crops [3; 16; 42; 43]. As a result, the vitamin C content of foods may decrease during food preparation and storage. The decrease in its values occurs depending on the time and method of storage [43; 44]. During the process of preparation of the fruits used to obtain juices, different extraction methods are employed, which may alter the content of different compounds in the product [45]. Many authors state in their works that the degradation of ascorbic acid is mainly due to heat treatment and storage time [46; 47; 48; 49; 50; 51; 52]. To best preserve vitamin C, it is recommended that foods containing vitamin C should not be stored at all or only minimally processed during cooking [42]. Ascorbic acid is considered one of the most heat-sensitive nutrients in foods and indicates the loss of other nutrients. It can be easily degraded depending on several variables. The kinetics of degradation is significantly affected by many environmental factors, such as pH, temperature, light, and the presence of enzymes, oxygen, and metal catalysts. For these reasons, the temperature and the choice of packaging material are cornerstones of the food industry, as it affects food quality during storage. Since the concentration of vitamin C in fruits, vegetables, and beverages are considered a quality factor, it is essential to monitor it during food processing and storage to preserve (maintain) the quality of the processed juices.