Nutritional value, antioxidant activity and color properties of white-fleshed sweet potatoes in Vietnam

Abstract

Sweet potatoes have been considered an essential food source in the human diet for centuries. The study provides comprehensive knowledge on the physico-chemical properties and antioxidant potential of white-fleshed sweet potato (WFSP), to raise consumer awareness of its positive health effects and encourage its greater use. The study also explores whether the food is acidic or alkaline to enhance its health benefits, through Potential Renal Acid Load (PRAL) score. Phenolic acid components were identified and quantified by Ultra-Performance Liquid Chromatography (UPLC), while the functional groups of these compounds were determined by Fourier transform infrared (FTIR) spectroscopy. The results showed that WFSP contains high levels of minerals, including potassium 79.56 mg/100 g, phosphorus 18.69 mg/100 g, magnesium 9.58 mg/100 g and calcium 7.68 mg/100 g. Resistant starch is also present in WFSP at a relative amount of 1.12 %. The total polyphenol content and total flavonoid content were found to be 1.58 mg GAE/g and 0.69 mg QE/g, respectively and it was a source of antioxidant potential (with IC50 DPPH and IC50 ABTS·+ determined as 3.31 mg/mL and 0.38 mg/mL, respectively). WFSP was identified as an alkaline food with a negative value (-0.63). Low-PRAL/alkali-ash diets have been linked to a variety of health benefits, including an improved potassium-to-sodium ratio, less muscle wasting and higher intracellular magnesium concentrations. FTIR analysis showed that the phenolic components in WFSP contained 17 functional groups. UPLC analysis identified the main phenolic acids in WFSP as caffeic acid, coumaric acid and trans-ferulic acid, which are antioxidant compounds that can protect cells from damage.