Nutritional and physicochemical characterization of purple and red-fleshed genotypes of potatoes from different geographical regions

There is a recent increasing interest by food producers and consumers in colored potato varieties, mostly in Europe and the United States [1,2]. This interest is connected not only with the tubers' attractive physical and organoleptic qualities (color and taste), but also with their health beneficial chemical composition [2]. Colored varieties include: red skin/white flesh, red skin/red flesh, purple skin/marble flesh and purple skin/purple flesh [l]. This study reports the characterization often potatoes' genotypes with red and purple flesh, in terms of their nutritional and physicochemical composition. Their nutritional value (proteins, fat, ash, carbohydrates, and energetic value) and NaCl content were evaluated according to AOAC methodologies. The chemical composition was evaluated in terms of organic acids, fatty acids, and free sugars content through chromatographic analysis. Moreover, pH and color measurement of skin and flesh were also determined using a calibrated digital pH meter and a colorimeter, respectively. For this purpose, tubers often colored potato cultivars were obtained from the Leibniz Institute of Plant Genetics and Crop Plant Research in Germany. The ten varieties (Salad Blue, Shetland Black, Rosemary, Red Emmalie, Violette, Finish Blue, Red Cardinal, Kefermarkter Blue, Purple and UACH 0917), original from five deferent countries (Germany, Austria, United Kingdom, Finland and Chile), showed significant differences in their nutritional profiles. Despite of their genetic origin, ali tuber samples were grown in the same location in Germany in the year of 2017. The results showed the following nutrient content variation depending on the cultivar: carbohydrates: 174. 1±0.1 - 272. 2±0.5 g/kg fw; proteins: 18.0±0.3 - 22. 4±0.5 g/kg fw; fat: 0. 54±0.03 - 4.88±0.04 g/kg fw; and ash: 6.2±0.3 - 14. 7±0.2 g/kg fw. The energetic value ranged between 790. 7±0.9 and 1203±1 kcal/kg fw. NaCl content and pH measurements showed similar results among ali ten studied colored potatoes, whilst color results varied between red and purple-fleshed varieties. Understanding the nutritional and physicochemical composition of colored potatoes may help the selection of commercially useful genotypes and promote biodiversity [3]. Moreover, the organoleptic and health-promoting properties of purple and redfleshed potatoes illustrate their potential use in the food and nutraceutical industries.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financiai support to CIMO (UID/AGR/00690/2013), A. Fernandes grant (SFRH/BPD/114753/2016), and L. Barras contract. S. Sampaio is grateful to the Coordination for the Improvement ofHigher Educdtion Personnel (CAPES, Brazil) for her PhD grant.