This study compared two instrumental methods, namely uniaxial compression and texture profile analysis (TPA), with sensory evaluation in describing the textural properties of cooked sweetpotatoes. The steamed cooked samples (1.35 × 2.2 cm cylinder) of four cultivars and six selections were subjected to a trained texture profile panel for sensory ratings and the two instrumental methods for determination of the mechanical properties. Factor analysis indicated that the 15 sensory variables were grouped into 3 main factors, namely moistness‐firmness (factor 1), particles (factor 2), and fiber (factor 3). Among the instrumental parameters, shear stress of compression and fracturability, hardness, and gumminess of TPA correlated highly (R = 0.73–0.95) with both the mouthfeel and mechanical‐type sensory notes. These parameters of the two instrumental methods were linearly related (R2≥ 0.95) and could be converted from one to another with a high degree of reliability. Regression equations based on shear stress significantly explained (R2= 0.71–0.91) eight of the sensory notes. These instrumental parameters can be good predictors of cooked sweetpotato texture.

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Physicochochemical changes in cassava starch and flour associated with fermentation were investigated and related to textural properties of its flour pastes. Cyanide and pH decreased, while crude protein, acidity, and apparent amylose content increased in the fermented products. Average starch granule diameter, solubility, and swelling power were depressed, while gelatinization enthalpy increased. Amylograph of starch showed increased peak visocity temperature, reduced peak, breakdown, and setback viscosities, while Texture Profile Analysis showed a decreased in hardness, cohesiveness, elasticity, and gumminess of the fermented flour paste. The altered textural properties were attributed to greater starch granule stability due to short amylose‐like fragments formed by enzymatic hydrolysis of amylopectin.

Laboratory starches, isolated from seven sweetpotato selections grown at two locations in Peru, and commercially available Peruvian starch were characterized with regard to physicochemical properties. Chemical analyses included determination of nitrogen, ash, and amylose content. Physical characterization was based on results from differential scanning calorimetry (DSC), swelling power, solubility, and rheology of the pastes. We found that nitrogen and amylose content were not affected by location or selection, while ash content was affected by location. Results from the DSC analysis showed that selection identity (SI) did not affect DSC enthalpy, onset, peak, and final temperatures. Location affected only peak temperature. Investigation of starch swelling power showed that SI and location did not affect swelling power above 75°C, and that laboratory starch samples had greater swelling power than commercial samples. Solubility was affected by location, but not by SI. Maximum viscosities of heated starch slurries were not affected by SI or location. Although laboratory and commercial samples did not differ significantly in chemical composition, physical behavior of their pastes was significantly different.