Functional and pasting properties of cassava - sweetpotato starch blends

Starch is an important constituent in many foods and plays an obvious role in achieving the desired viscosity in products such as sauces, pie illings, salad dressings, puddings, etc. Blending different starches has been reported to result in desirable functional properties which help to overcome some end-use limitations of native starches. Therefore, the purpose of this study was to determine the functional and pasting properties of cassava–sweetpotato starch blends with the aim of improving the utilization of these starches in food and non-food applications. Starches were isolated from cassava roots and sweetpotato tubers using standard procedures. The starches were dried, milled, and blended in different proportions. The functional and pasting characteristics of the starch blends were determined using standard analytical procedures and instruments. The functional properties of the starch blends were signiicantly different ( P<0.05) from 100% cassava and sweetpotato starches except in bulk density and pH. Bulk density ranged from 0.64 to 0.67 g/ml, Water absorption index ranged from 69.07 to 87.00% and dispersibility from 64.80 to 87.60%. The least gelation concentration ranged between 2.00 and 3.73%. The pH of the starch blends was between 6.70 and 6.80. The swelling power of the starch blends increased with increasing temperature and was considerably higher than that of 100% sweetpotato starch but lower than that of 100% cassava starch. Total titratable acidity of the starch blends was lower than that of 100% cassava and sweetpotato starches. The pasting proile of the starch blends was signiicantly different from that of the 100% cassava and sweetpotato starches. Peak viscosity ( 310.05−379.29 RVU), trough (162.67−203.42 RVU), breakdown viscosity (169.13−177.46, RVU), and inal viscosity (200.50−274.50 RVU) were lower than those of 100% cassava and sweetpotato starches. Set back viscosity ranged between 66.30 and 82.00 RVU. Time to attain peak viscosity ranged from 4.47 to 4.97 min, while the starches, pasting temperature ranged from 73.65 to 91.60 o C. Blending sweetpotato starch with cassava starch signiicantly improves some functional properties of sweetpotato starch. The blend containing 75% cassava starch and 25% sweetpotato starch showed higher pasting stability than 100% cassava and sweetpotato starches, due to its low setback viscosity.