Comparison of Caffeoylquinic Acids and Functional Properties of Domestic Sweet Potato (Ipomoea batatas (L.) Lam.) Storage Roots with Established Overseas Varieties.

Root samples of sweet potato varieties originating from South Africa ('Ndou', 'Bophelo', 'Monate', and 'Blesbok'), the USA ('Beauregard'), and Peru ('199062.1') were analyzed using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/QTOF/MS) and chemometrics to characterize and compare the locally developed varieties with well-known established overseas varieties. The highest total phenol content was detected in 'Bophelo', followed by 'Beauregard' and Peruvian variety '199062.1'. The Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) model classified the storage roots of six sweet potato varieties into two clusters. In the OPLS-DA scatter plot, one cluster, which included Peruvian variety '199062.1', was separated from the others. L-tryptophan and 3-caffeoylquinic acid (CQA) showed variable importance in projection (VIP) scores greater than 1.5. Based on the OPLS-DA-S-plot, L-tryptophan separated the other varieties from Peruvian variety '199062.1'. Peruvian variety '199062.1' contained higher concentrations of CQA (1,3-diCQA, 1,4-diCQA, 3,5-diCQA, 4,5-diCQA, 3-CQA, and 5-CQA) and 5-hydroxy-6-methoxycoumarin 7-glucoside than other varieties. Among all sweet potato varieties analyzed, Peruvian variety '199062.1' showed the highest ferric reducing antioxidant power (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free radical scavenging activity, and [2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate)] scavenging activity. Among the local sweet potato varieties, 'Bophelo' has the greatest potential for commercialization as it is the richest source of CQA.

An Evaluation of Phenolic Compounds, Carotenoids, and Antioxidant Properties in Leaves of South African Cultivars, Peruvian 199062.1 and USA's Beauregard.

In this study, leaves of sweet potato cultivars from South Africa ("Ndou," "Bophelo," "Monate," and "Blesbok"), "Beauregard," a sweet potato cultivar from the USA, and a Peruvian cultivar "199062. 1" were analyzed using UPLC/QTOF/MS and chemometrics, with the aim of characterizing the locally developed sweet potato cultivars and comparing them with already well-known established varieties on the market. A set of 13 phenolic compounds was identified. A partial least squares discriminant analysis, a hierarchical cluster analysis, and variables importance in projection were used to successfully distinguish sweet potato varieties based on their distinct metabolites. Caffeic acid enabled to distinguish Cluster 1 leaves of varieties ("Beauregard" and "Ndou") from Cluster 2 ("199062.1," "Bophelo," "Monate," and "Blesbok"). The leaves of "Bophelo" contained the highest concentrations of rutin, quercetin 3-O-galactoside, 3-caffeoylquinic acid (3-CQA), (5-CQA), 1,3 dicaffeoylquinic acid (1,3-diCQA), 1,4-diCQA, and 3,5-diCQA. Furthermore, Bophelo leaves showed the highest antioxidant activities (FRAP 19.69 mM TEACg-1 and IC50 values of (3.51 and 3.43 mg ml-1) for DPPH and ABTS, respectively, compared to the other varieties. Leaves of "Blesbok" contained the highest levels of ß-carotene (10.27 mg kg-1) and zeaxanthin (5.02 mg kg-1) on a dry weight basis compared to all other varieties. This study demonstrated that the leaves of local cultivars "Bophelo" and "Blesbok" have the potential to become functional ingredients for food processing.