Influence of Time of Harvest and Variety on the Pasting Properties of Starch from Three Cassava Varieties- A Response Surface Analysis

Aims: Three cassava varieties TME 419, TMS 30572 and TMS 98/0505 were harvested at three months interval from maturity- 10, 13 and 16months. The aim was to optimize and determine the influence of experimental variables – time of harvest and cassava variety on their pasting properties.

Study Design: Starch was isolated from the cassava varieties at each harvesting regime and their pasting properties were determined using Rapid Visco Analyser.

Place and Duration of Study: Cassava tubers were obtained from National Research Institute, Umudike Abia State, starch was isolated at the Biochemistry Laboratory of National Research Institute, Umudike and the pasting work was done at Central Laboratory of the University of Ibadan, Oyo State.

Methodology: Sixteen experimental runs were generated. Center point was replicated seven times. Star and corner points were not replicated. Data obtained were subjected to response surface analysis. Optimization was done using optimization toolbox of Matlab r2012a software.

Results: Peak viscosity ranged between 5946RVU (TMS 98/0505-16 months) and 7327RVU (TME 419-13 months). Trough ranged between 2200RVU (TMS 30572-13 months) and 3463RVU (TMS 30572-10 months), Breakdown between 2878RVU(TMS 98/0505-16 months) and 4689RVU(TME 419-13 months). Final viscosity ranged from 3068RVU (TME 419-16 months) to 4154RVU (TMS 30572- 10 months). Setback ranged from 522RVU (TME 419-16months) and 1462RVU (TME 419-13months). Pasting temperature ranged between 75.05°C (TMS 30572- 16months) and 78.78°C (TMS 98/0505-10 months). Peak time ranged from 3.80 min (TMS 30572-13months) to 4.47 min (TME 419-10months).Variety and time of harvesting significantly (P=0.05) affected the pasting properties of starch from the cassava varieties. Optimization gave the minimum and maximum values of pasting parameters obtainable.

Conclusion: Variety and time of harvesting significantly affected the pasting properties of starch from the cassava varieties.