Variation in Chemical Composition and Pasting Properties of Starches of Different Potato Varieties Grown at Different Locations in Amhara Region, Ethiopia

Abstract

Potato starches isolated from 25 different varieties grown at three different locations in the Amhara region of Ethiopia in 2011 were studied to determine their variation based on amylose content (AMC) and amylopectin content (APC), and pasting properties by iodine colorimetry and Rapid Visco Analyzer procedures, respectively. The results revealed highly significant (P < 0.01) differences between cultivar and location. The mean values for the AMC and APC ranged from 20.86% (Jalene) to 30.58% (Ater Abeba), and 69.42% (Ater Abeba) to 79.14% (Jalene), respectively. The mean AMC index of locations ranged from 24.50% to 26.24% for the Adet and Debretabor sites. The peak viscosity (PV), hot paste viscosity (HPV), breakdown viscosity (BDV), cool paste viscosity (CV) and setback viscosity (SBV) ranged from 225.10 to 426.72, 135.01 to 191.83, 56.47 to 259.32, 173.68 to 247.51 and 27.17 to 68.15 Rapid Visco units (RVU), respectively, while the pasting time (PT) and pasting temperature (Ptemp) ranged between 3.35 to 4.91 minutes and 68.16 to 70.89 °C, respectively. Correlation among starch properties showed significant (P < 0.01 and P < 0.05) associations except for PV with CPV and HPV with BDV and SBV. The highest PV (538 RVU), HPV (207 RVU), BDV (363 RVU), and CV (265 RVU) values were recorded at the cool Debretabor site. Thus, the study revealed the significant genetic variation present among varieties with regard to the starch chemical composition and pasting properties and the effects of growing location on these properties.