Total Phenolic and Total Flavonoid Content, Antioxidant Activity, and Nutritional Profile of Ziziphus mauritiana Fruit Juice

Ziziphus mauritiana is a plant species belonging to the Rhamnaceae family. It is commonly found in tropical and subtropical regions of Asia, and in Indonesia, this plant grows wild and thrives on the islands of Bali, Lombok and Sumbawa. The fruits of Z. mauritiana are edible, however, in Indonesia, it is underutilized and has very low economic value. To evaluate its possibility to be developed as a functional food, this study was conducted to determine the total phenolics and flavonoids, dietary fiber, and nutrients contained in the fruit juice of Ziziphus mauritiana. Total phenols and flavonoids contents were determined using Folin Ciocalteu and AlCl3 methods, respectively. The in vitro antioxidant activity of the juice was evaluated using the DPPH method. The content of soluble and insoluble dietary fiber was determined using the standard AOAC analysis method, and proximates analysis was conducted in accordance with SNI 01-2891-1992.  The results of this study revealed that freeze-dried juice of Z. mauritiana fruit has total phenols content of 1690 mg GAE/100g, total flavonoids of 15.10 mg QE/100g, soluble dietary fiber of 0.61%, and insoluble dietary fiber 2.03%. However, the antioxidant activity of Ziziphus mauritiana fruit juice was weak with IC50 328.54 ppm. The proximate analysis revealed the crude fiber in the freeze-dried fruit juice was 0.56%, carbohydrates 82.43%, protein 3.34%, fats 0.31%, ash 3.62%, and water 10.30%. In conclusion, Ziziphus mauritiana fruit juice has a high content of total phenolic substances, high dietary fiber, and high nutritional value, therefore it has a good potential to be developed as a functional food.