Aníbal M. Reyes1, Adrián Aicardo1, Cecilia Chavarría1, Joanna Lado2, Rafael Radi1, Mauricio Mastrogiovanni1
Purple sweet potatoes are annual or perennial herbs belonging to the Convolvulaceae family, with flesh ranging from purple to dark purple. In addition to the nutrients found in common sweet potatoes, they are rich in anthocyanins and represent an important source of dietary fiber, minerals, vitamins, and other bioactive compounds. Anthocyanins are phenolic compounds (polyphenols) present in the flesh and skin of fruits, flowers, and roots of various plant species, performing a wide array of biological functions. The anthocyanins in purple sweet potatoes are versatile natural pigments with numerous health benefits, and growing scientific evidence supports their beneficial effects on human health, positioning these cultivars as potential functional foods. Furthermore, their pH-dependent color changes and high degree of acylation confer some properties that make them attractive for applications in the food, cosmetic, and pharmaceutical industries.
In this study, we analyzed the anthocyanin content of different sweet potato varieties developed by the agrifood breeding program of the National Institute of Agricultural Research (INIA, Salto Grande, Uruguay) to provide data that could enhance the value of this product. Three varieties of sweet potatoes were examined: a white-fleshed variety (RUBI63) and two anthocyanin-rich varieties (A1807.19 and F23A2.2). Anthocyanins extraction from sweet potatoes was conducted using ultrasound-assisted extraction in acid hydroalcoholic solvents, and chemical characterization was performed by HPLC-UV and HPLC-MS/MS. A total of 15 and 17 anthocyanins were identified in A1807.19 and F23A2.2, respectively. A1807.19 was dominated by cyanidin derivatives, whereas F23A2.2 exhibited a predominance of peonidin derivatives. Anthocyanins occurred in non-acylated, monoacylated, and diacylated forms, primarily conjugated with caffeic, ferulic, and p-hydroxybenzoic acids, consistent with profiles reported for Asian cultivars.
Quantitative analysis revealed total anthocyanin contents of 1.55 mg Cia eq/g in A1807.19 and 2.37 mg Cia eq/g in F23A2.2, values comparable to those reported for Chinese and Korean varieties. Additionally, F23A2.2 contained a higher proportion of diacylated anthocyanins, which may enhance pigment stability and expand its potential applications.
Looking forward, we propose to conduct untargeted metabolomic and transcriptomic studies of these purple sweet potato strains, as consumer surveys have highlighted certain sensory limitations: purple sweet potatoes exhibit a dense, fibrous texture, low moisture content, and a distinctive sweet flavor, distinguishing them from more widely accepted cultivars. These organoleptic characteristics are closely linked to tuber quality parameters such as dry matter content, starch structure, soluble sugars, and volatile compounds contributing to aroma. In this context, a deeper understanding of their chemical composition is essential for elucidating color formation mechanisms and assessing both quality and nutritional value.
Participating in this metabolomics school is a key step toward achieving this future goal, as it offers not only high-quality training but also the invaluable opportunity to engage with leading experts in the field and foster scientific exchange.
Agradecimentos: This work was partially funded by PEDECIBA (Programa de Desarrollo de las Ciencias Básicas) and Programa de Alimentos y Salud Humana (PAyS) IDB—R.O.U. (4950/OC-UR).