EFFECT OF DRYING METHODS ON THE YIELD, PHYTOCHEMICAL COMPOSITION AND ANTIOXIDANT ACTIVITIES OF POTATO (SOLANUM TUBEROSUM) AND TWO SWEET POTATO (IPOMOEA BATATAS) VARIETIES
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Date
2018-03-13
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CARPATHIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Abstract
ABSTRACT In various parts of the world, drying technologies have been developed to convert tubers into flour which can be used as ingredients in numerous food products. Potato and sweet potato are known to contain certain bioactive constituents that are capable of scavenging free radicals and reducing the risk of degenerative diseases. The effects of two drying methods (sun and solar) on flour yield, antioxidant activity and phytochemical composition of Irish potato (IP) and two sweet potato varieties (orange and white-fleshed) were evaluated. The flour yield (15.20–19.0%) varied significantly (p˂0.05) among the samples. The DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical scavenging activities of the flour samples varied with drying methods and the extracts' concentrations. The total antioxidant activities expressed in terms of the % inhibition (53.58–90.62%) and EC50 values (0.584–45.214 mg/ml) were observed to be significantly affected (p˂0.05) by the drying methods. Drying processes generally increased the total phenolics (18.72–21.60 mg GAE/g) and total flavonoids (0.50–1.15 mg QE/g) contents of the tubers. The effect of sun-drying was observed to be less favorable on the white-fleshed sweet potato (WFSP) samples compared to solar-drying method. Although solar-dried orange-fleshed sweet potato (OFSP) flour had the highest total antioxidant activity, sun-drying method produced IP and OFSP flours with the highest total phenolics and total flavonoids contents respectively. Sun and solar dried OFSP had the highest beta-carotene content (BCC) and only the BCC of Irish potato significantly varied (p˂0.05) with drying methods. This study also revealed that the effects of drying methods on the yield, phytochemical and antioxidant activities of the samples were mostly tuber (potato and sweet potato) dependent.
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Keywords
Antioxidant activity, Drying method, Irish potato, Phytochemical composition, Sweet potato varieties