Vitamin C Content of Jujube Fruit and Its Changes during Fruit Development and Processing

Jujube (Ziziphus jujuba), also called Chinese date, belongs to the Rhimnaceae family. Jujube has been cultivated for more than 4000 years in China for both nutritional and medicinal uses. Jujube fruit not only tastes sweet but its vitamin C (Vc) content is higher than most well-known ‘Vc-rich’ fruit and vegetables like orange, kiwi fruit, strawberry, papaya, pineapple, chili pepper, green/red pepper, kale, broccoli, etc. Jujubes are also called natural vitamin C pills.  With its handy size, it would be a good source for people’s daily vitamin C requirement. Jujube cultivars were introduced into the US 100 years ago, but the research and commercially available cultivars are very limited. Jujubes are distributed over a wide area in the US and they grow and produce well especially in the Southwest. To promote this nutritious fruit and increase its planting acreage, the NMSU Alcalde Center has collected cultivars in the US and imported cultivars directly from China for a total of over 50 cultivars.  Fruit vitamin C content of 40 cultivars and its changes after four basic cooking procedures- steaming, boiling, pie making, and jam making were measured. Cultivars varied in their vitamin C content from 200 to 600 mg/100 g fresh weight. During the fruit maturation process, the green/cream stage fruit had higher vitamin C content than fully matured fruit (80-100% red/brown color). If customers are concerned about jujube’s health benefit, a cultivar’s vitamin C content should be considered as well as other fruit quality characteristics. The small fruit of sour jujube (Ziziphus spinosa) is without much flesh for fresh eating, but has higher vitamin C content than cultivated cultivars (Z. jujuba) and could be used for processing healthy drinks or food. After steaming or boiling, over 80% of vitamin C was preserved in the fruit. When fruit were used for jam, the final product retained over 80% of the vitamin C content of the fresh fruit. Jujube pie only preserved 45-50% of its original vitamin C content. Compared with reports of over 90% vitamin C loss during the sun-drying process, fresh processed products preserve vitamin C well.