Abstract

CASTANETA, Grover; CASTANETA, Ruddy  and  PENARRIETA, J. Mauricio. Cambios fisicoquímicos por exposición a la radiación solar en tubérculos de oxalis tuberosa, “oca” cultivados en Bolivia. Rev. Bol. Quim [online]. 2022, vol.39, n.2, pp.18-29. ISSN 0250-5460.  https://doi.org/10.34098/2078-3949.39.2.3.

As part of a Bolivian food valorization program based on its chemical properties, some physicochemical changes were studied in the tubers of Oxalis tuberosa, a species known in the Andean region under the name of "oca". The tuber of Oxalis tuberosa is a representative food of the Andes of South America and is the third most cultivated tuber in Bolivia after potatoes and cassava. Oca is a good source of starch, minerals, vitamin C and phenolic compounds. Despite being a food with such characteristics, its production is declining, since it is mostly intended for self-consumption. In order to increase its natural sweetness (increase in free sugars) its exposure to sunlight prior to consumption is customary, making thus, more acceptable to the consumers. In the present work, the influence of total solar radiation on some physicochemical properties was investigated: soluble solids, color, humidity, titratable acidity and pH of some oca accessions produced in La Paz, Bolivia. Freshly harvested varieties and varieties from local markets were evaluated and exposed to the sun for 10 days (5 h/day). The results indicate that most of the samples do not lose moisture and titratable acidity significantly, but there are significant changes in soluble solids, color and pH. It was possible to determine that the optimum sun exposure time to reach maximum sweetness ranges from 5 to 10 days in freshly harvested samples and between 3 to 6 days in commercial samples.

Keywords : Andean food; ^oBrix; Sweetening; Oxalidaceae; Solar radiation; Sunlight; Tuber.

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