A Study on the Biodiversity of Pigmented Andean Potatoes: Nutritional Profile and Phenolic Composition.

The characterization of six varieties of native Andean potatoes with a wide biodiversity in tuber shape, flesh, and skin color was performed, through the determination of their proximate composition, mineral content, and phenolic profile. Minerals concentration revealed significant genotypic variation. Potassium was the most abundant element in all varieties, ranging from 7272.9 to 13,059.9 µg/g and from 12,418 to 17,388.6 µg/g dried weight for the flesh and skin samples, respectively. Iron content was relevant, ranging from 20.5 to 39.9 µg/g and from 112.2 to 288.8 µg/g dried weight in flesh and skin samples, respectively. Phenolic compounds were consistently higher in the skin than in the flesh. The total content varied greatly from 19.5 to 2015.3 µg/g and from 1592.3 to 14807.3 µg/g dried weight for flesh and skin tissues, respectively. 5-caffeoylquinic acid was 74% of the total phenolic acids. Different pattern of anthocyanins was found, depending on the color of the variety; the red genotypes contained predominantly pelargonidin derivatives, while the purple samples had petunidin as a major anthocyanidin. This study increases the knowledge of the composition of the local Andean varieties (which are only scarcely studied so far), helping to enhance these genotypes and the conservation of biodiversity.

Effect of cooking on the anthocyanins, phenolic acids, glycoalkaloids, and resistant starch content in two pigmented cultivars of Solanum tuberosum L.

HPLC/DAD/MS analysis of the phenolic acids and anthocyanin content of three cultivars of Solanum tuberosum L. (Vitelotte Noire, Highland Burgundy Red, with pigmented flesh, and Kennebec with white pulp) was performed. The analyses were carried out both on fresh tubers and after cooking treatments (boiling and microwaves). Starch digestibility and the % of resistant starch were also determined on cooked tubers by in vitro methods. For the pigmented potatoes, the heating treatment did not cause any changes in the phenolic acids content, while anthocyanins showed only a small decrement (16-29%). The cv. Highland Burgundy Red showed anthocyanins and phenolic acid concentrations close to 1 g/kg and more than 1.1 g/kg, respectively. Vitellotte Noire showed the highest amounts of resistant starch. Potato starch digestibility and % of resistant starch, considered as a component of dietary fiber, were affected both by cultivar and by heating/cooling treatments.