STUDY OF VITAMIN C AND TOTAL PHENOLIC CONTENTS, AND ANTIOXIDANT ACTIVITY OF EXTRACTS OF CUSTARD APPLE PULP GROWN IN THAI NGUYEN PROVINCE AND SURROUNDING AREA

Abstract

Currently, custard apple (Annona squamosa) has attracted increasing attention from those interested in health - promoting foods due to its high and diverse phytochemical content. This study was conducted to evaluate the vitamin C, total polyphenol contents, and antioxidant activity of custard apple pulp cultivated in Thai Nguyen and adjacent regions. Vitamin C and total phenolic contents were determined using ascorbic acid and gallic acid calibration curves, respectively. The DPPH free radical scavenging assay and total reducing power assay were employed to assess antioxidant capacity. The Taiwanese custard apple sample exhibited the highest vitamin C content, followed by the Dong Banh sample, while the La Hien sample showed the lowest, ranging from 2.56 to 3.17 mg/g dry weight. The three custard apple samples displayed comparable polyphenol contents and similar DPPH radical scavenging abilities. The Taiwanese sample demonstrated the strongest total reducing power, whereas the Dong Banh sample had the weakest, with EC₅₀ (half maximal effective concentration) values of 126.79 and 149.28 µg/mL, respectively. The results indicate that extracts from these custard apple samples possess promising potential for application in the production of flavoring agents or functional foods.