Prediction of antioxidant compounds in water spinach ( Ipomoea aquatica Forsk.) across peri-urban food value chains in Indonesia using near infrared spectroscopy

Water spinach or “ kangkung ” ( Ipomoea aquatica Forsk.) is a semi-aquatic leafy vegetable belonging to the family Convolvulaceae. This plant is widely used in tropical and sub-tropical regions of Southeast Asia, grow well in moist soils and aquatic environments, making it a valuable crop for lowland and wetland agriculture. This species has long been cultivated and consumed across Asia for its nutritional value and its role in traditional medicine. The aim of this study was to evaluate the use of near infrared (NIR) spectroscopy to predict phenolic compounds, β-carotene and total chlorophyll of I. aquatica obtained from four diverse geographical locations of Indonesia representing peri-urban areas near Greater Jakarta, Bandung, Yogyakarta, and Surabaya given their critical position to link between rural agricultural production and urban consumption and food systems. The coefficient of determination in cross validation (r 2 CV ) and the standard error in cross validation (SECV) were 0.68 (SECV: 2.4 mg gallic acid equivalents (GAE)/g dry weight (DW)), 0.65 (SECV: 42.4 µmol Fe 2+ equivalents/g DW), 0.56 (SECV: 25.8 μmol Trolox equivalents (TE)/g DW), 0.25 (SECV: 15.1 mg/100 g DW) and 0.68 (SECV: 0.23 mg/g DW) for total phenolic compounds (TPC), corresponding to ferric reducing antioxidant power (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) ABTS, β-carotene and total chlorophyll, respectively. The RPD values ranged between 1.1 and 2.1 indicating that the cross-validation models are adequate for screening purposes. The standard errors of prediction (SEP) were 2 mg GAE/g DW, 44.4 µmol Fe 2+ equivalents/g DW, 30.5 μmol TE/g DW, and 0.21 mg/g DW for TPC, FRAP, ABTS, and total chlorophyll, respectively. No satisfactory prediction results were obtained for β-carotene. The development and implementation of rapid analytical methods such as those based on the utilization of NIR spectroscopy, provide with tools that can be used for early dietary interventions, to monitor bioactive compounds, ensuring food authenticity and security, and supporting nutrition-sensitive and sustainable agriculture.