Abstract
ABSTRACT: Purple-fleshed sweet potatoes are rich in phenolic compounds, such as anthocyanins, and also exhibit hypoglycemic properties. Anthocyanins are natural antioxidants with the capacity to inhibit or delay injuries caused by free radicals. Drying is one of the most commonly used vegetable preservation methods; although,it has parameters that affect the sensory and physicochemical properties of the final product. The present study assessed the impact of drying temperatures (40, 50, and 60 °C) on the purple-fleshed sweet potato. Cut, unpeeled potato slices of 4 cm in diameter and 3 mm in thickness were dried in an oven with hot air circulation. The effect of the different temperatures on the antioxidant capacity, phenolic compound content, and total and monomeric quantities of anthocyanins in purple sweet potato were measured, and a mathematical model describing the drying kinetics was determined. According to the results observed, the process at 40 °C better preserved the phenolic compounds; however, drying at 50 °C was more efficient for conserving the antioxidant capacity measured by the H + capture method performed by DDPH, and for the total and monomeric quantities of anthocyanins. The mathematical models that best described the kinetic curves were those of Henderson and Pabis, and Page.
Highlights
Sweet potato (Ipomoea batatas L.) is a plant originating in America that is classified by its format, size, and skin and pulp color, among other factors
Among the numerous varieties of skin and pulp colors of sweet potatoes, the purple pulp is highlighted for its bioactive properties due to phenolic compounds such as anthocyanins, and for its hypoglycemic capacity (JIANTENG XU et al, 2015)
The quantification of total and monomeric anthocyanins was performed using the differential pH method proposed by GIUSTI & WROLSTAD (2001), with absorbances measured at λ510 and λ700 nm for pH 1.0 and 4.5, respectively in an SP 22 visible UV spectrophotometer.Results were expressed in cyanidin equivalent milligrams – three glycosides per kilogram of purple sweet potato dry mass
Summary
Sweet potato (Ipomoea batatas L.) is a plant originating in America that is classified by its format, size, and skin and pulp color, among other factors. This study evaluated the impact of different drying temperatures in a dehydrator with hot air circulation on the antioxidant capacity, phenolic compound content, and total and monomeric anthocyanins in purple-fleshed sweet potato, as well as to propose a mathematical model that could describe the drying kinetics involved.
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