In Vitro Digestibility and Physicochemical Properties of Isolated Starch from Potatoes (Solanum tuberosum and Solanum subsp. andigena) Varieties Commercialized in the Andean Region: Ecuador

Starches from nine potato tubers marketed in Ecuador were evaluated for their in vitro digestibility, morphological, thermal, and pasting properties. Raw starches are resistant to enzymatic hydrolysis, but their digestibility increases significantly after gelatinization. Rapidly digestible starch (RDS) increases from 3.8 to 6.2 folds, while the contents of both slowly digestible starch at 120 min (SDS120) and 240 min (SDS240) decrease from 17.9-34%, and 10.2-34% (raw starch), to 11.2-20.1%, and 4.2-16% (gelatinized starches), respectively. Also, resistant starch (RS) content diminishes from 33.7-45.5% to 8.50-14.8%. In addition, total starch (86-95%), average granular size (26.2-47.23 mu m), consists mainly of elliptical or ground granules, and pasting properties (Peak viscosity: 2400-3240 cP; final viscosity: 1236-3507 cP; breakdown: 2236-5424 cP; setback: 510-3477; and pasting temperature 60.6-66.2 degrees C) differed significantly (p < 0.5). Amylose (21.1-26.7%), and thermal properties (T-o: 57.1-62.3 degrees C; T-p: 58.2-63.9 degrees C; T-f: 59-64.9 degrees C), except gelatinization enthalpy (67.7-168.6 J g(1)), do not differ significantly (p < 0.5). This study provides important information for developing products, mainly those with reduced starch digestibility, using different potato varieties.