EVALUATION OF SELECTED QUALITATIVE PARAMETERS OF SWEET POTATO IN DEPENDENCY ON ITS CULTIVAR IN SLOVAKIA

Abstract

In this study, selected qualitative parameters (total carotenoids, vitamin C, total polyphenols) of sweet potatoes (Ipomoea batatas L.) grown in Slovakia were evaluated. The field experiment was established in the area of the Slovak University of Agriculture in Nitra in 2017. In experiment, registered cultivar 'Beauregard' was used as a comparable cultivar. Other three cultivars ('Dubaian', 'Višnjica white', Višnjica purple') were marked according to the market place from which tubers for seedling production were bought.  The sweet potatoes were grown by hillock system and plants were mulched by black non-woven textile. The seedlings were planted on the 1st June 2017. The tuber harvest were realised on the 13th September 2017 and qualitative parameters were analysed immediately after harvest. The carotenoid and polyphenol content was determined spectrophotometrically (polyphenols in lyophilised sample; expressed in mg of gallic acid equivalent.kg^-1 of dry weight) and vitamin C content chromatographically (HPLC). The statistically significant differences of parameter content were found among tested sweet potato cultivars. The highest total carotenoid content (TCC) was found in cultivar 'Dubaian' (107.04 mg.kg^-1 fresh weight). Generally, significant differences of TCC were detected between cultivars with orange flesh colour (64.87 mg.kg^-1 f. w.;107.04 mg.kg^-1 f. w.) and cultivars with purple and white flesh colour (3.02 mg.kg^-1 f. w.; 8.00 mg.kg^-1 f. w.). The highest content of total polyphenols was found in cultivar with purple flesh of tubers - 'Višnjica purple' (5398.77 mg GAE.kg^-1 dry weight). Other cultivars were characterized by expressively lower values of total polyphenol content (1557.02-2412.91 mg GAE.kg^-1 d. w.). The highest vitamin C content was determined in cultivar 'Dubaian' (436.83 f. w.), following by cultivars 'Beauregard' (309.37 f. w.), 'Višnjica purple' (233.27 f. w.) and 'Višnjica white' (205.73 f. w.). Results of this study showed significant variability of polyphenol and carotenoid content in different-coloured sweet potatoes.

Keywords

• sweet potato,cultivar,carotenoids,polyphenols,vitamin C

References

1. Alam, M.K., Rana, Z.H., Islam, S.N. 2016. Comparison of the Proximate Composition, Total Carotenoids and Total Polyphenol Content of Nine Orange-Fleshed Sweet Potato Varieties Grown in Bangladesh. Foods,, 5(3):64.
2. Away, A. K., Nawiri, M. P., Nyambaka, H. N. 2013. Nutrient variation in coloured varieties of Ipomoea batatas grown in Vihiga County, Western Kenya. International Food Research Journal, 20(2): 819-825.
3. Barrera, W. A., Picha, D. H. 2014. Ascorbic Acid, Thiamin, Riboflavin, and Vitamin B6 Contents Vary between Sweetpotato Tissue Types. HortScience, 49(11): 1470-1475.
4. Du, J., Cullen J.J., Buettner G.R. 2012. Ascorbic acid: chemistry, biology and the treatment of cancer. Biochim Biophys Acta, 1826:443-457.
5. Eldashan, O.A., Singab, A.N.B. 2013. Carotenoids. Journal of Pharmacognosy and Phytochemistry, 2(1):225-234.
6. Faostat - Food and Agriculture Organization of the United Nations. 2018 [online]. [Cit. 19.5.2018]. Available from: http://www.fao.org/faostat/en/#data/QC/visualize
7. Grace, M. H., Yousef, G. G., Gustafson, S. J., Truong, V. D., Yencho, G. C., Lila, M. A. 2014. Phytochemical changes in phenolics, anthocyanins, ascorbic acid, and carotenoids associated with sweetpotato storage and impacts on bioactive properties. Food Chemistry, 145: 717-724.
8. Hegedűsová, A., Mezeyová, I., Andrejiová, A. 2015. Analyses methods of biologically active substances. Slovak University of Agriculture, Nitra, 75 p.

9. Ji, H., Zhang, H., Li, H., Li. Y. 2015. Analysis on the Nutrition Composition and Antioxidant Activity of Different Types of Sweet Potato Cultivars. Food and Nutrition Sciences, 6(1): 161-167.
10. Lachman, J., Hejtmánková, A., Dudjak, E. 2003. Content polyphenolic antioxidants and phenolcarboxylic acids in selected parts of yacon. Vitamins 2003 - Přírodní antioxidanty a volné radikály. Pardubice University, Pardubice, 89-97.
11. Loebenstein, G., Thottappilly, G. 2009. The sweet potato. Spinger, Dordrecht, 522 p.
12. Mezzomo, N., Ferreira, S.R.S. 2016. Carotenoids Functionality, Sources, and Processing by Supercritical Technology: A Review. Journal of Chemistry, 2016:1-16.
13. Mitra, S. 2012. Nutritional Status of Orange-Fleshed Sweet Potatoes in Allevviating Vitamin A Malnutition through a Food-Based Approach. Journal of Nutrition & Food Sciences, 2(8): 1-3.
14. Musilová, J., Bystrická, J., Árvay, J., Harangózo, Ľ. 2017. Polyphenols and phenolic acids in sweet potato (Ipomoea batatas L.) roots. Potravinarstvo, 11(1):82-87.
15. Riccioni, G. 2009. Carotenoids and cardiovascular disease. Current Atherosclerosis Reports, 11(6):434-439.
16. Tang, Y., Cai, W., Xu, B. 2015. Profiles of phenolics, carotenoids and antioxidative capacities of thermal processed white, yellow, orange and purple sweet potatoes grown in Guilin, China. Food Science and Human Wellness, 4(3): 123-132.
17. Teow, C. C., Truong, V. D., Mc Feeters, R. F., Thompson, R. L., Pecota, K. V., Yencho, C. 2007. Antioxidant activities, phenolic and β-carotene contents of sweet potato genotypes with varying flesh colours. Food Chemistry, 103(3): 829-838.
18. USDA - USDA National Nutrient Database for Standard Reference, release 28, U.S. Department of Agriculture, Agricultural Research Service [online]. [Cit. 21.5.2018]. Available from: http://ndb.nal.usda.gov/ndb/search
19. Wu, X., Sun, C., Yang, L., Zeng, G., Liu, Z., Li, Y. 2008. β-Carotene content in sweet potato varieties from China and the effect of preparation on β-carotene retention in the Yanshu No. 5. Innovative Food Science and Emerging Technologies, 9(4): 581-586.
20. Xu, L., Qu, Y-H., Chu, X-D., Wang, R., Nelson, H.H., Gao, Y-T., Yuan, J-M. 2015. Urinary Levels of N-Nitroso Compounds in Relation to Risk of Gastric Cancer: Findings from the Shanghai Cohort Study. PLoS ONE, 10(2):1-16.
21. Yildirim, Z., Tokuşğlu, Ö., Öztürk, G. 2011. Determination of sweet potato [Ipomoea batatas (L.) Lam] genotypes suitable to the Aegean region of Turkey. Turkish Journal of Field Crops, 16(1): 48-53.