Physicochemical and rheological characterization of Andean tuber starches: Potato (Solanum tuberosum ssp Andigenum), Oca (Oxalis tuberosa Molina) and Papalisa (Ullucus tuberosus Caldas)

The physicochemical and rheological properties of starches from four land races of Andean potato (Cuarentona, Rosadita, Imilla, and Waycha), and Oca and Papalisa tubers were investigated and compared against conventional potato starch. Proximate composition studies showed that the protein content in the studied starches varied between 0.29 and1.18% w/w, the ash content between 0.24 and 1.14% w/w, and the lipid content between 0.14 and 0.34% w/w. Scanning electron microscopy investigations showed differences in shape of the granules of Andean potatoes and Oca and Papalisa. The mean sizeD[4,3] of the granules ranged between 23.3 and 48.11 mu m. Papalisa was the starch with the lowest AM content (20.4%, w/w) and Rosadita had the greatest (28.03%, w/w). The gelatinization enthalpy ranged from 18.7 to 14.8 J/g and the gelatinization temperature between 65.5 and 60.8 degrees C. Viscograms of starch pastes showed that Cuarentona was the sample with the greatest peak viscosity (3152 cP) and presented the greatest final viscosity (3222 cP). The Andean potato and tuber starches exhibited low breakdown values. The relationship between the physicochemical and rheological properties was analyzed by principal component analysis (PCA). The results indicated that Oca and Papalisa starches were different from the Andean potato starches. Cuarentona starch showed the greatest consistency coefficient (Pa . s(-n)) (K), storage modulus (Pa) (G'), peak viscosity, final viscosity, and Oca starch the lowest ones. The protein content affected the peak viscosity and setback of the samples. The results suggest that these starches have similar properties to those of conventional potato starch.