Functional properties of cowpea (Vigna unguiculata) starch as modified by guar, pectin, and xanthan gums

In the present study, the effect of different hydrocolloids (guar, xanthan, and pectin) were evaluated on some functional properties of cowpea starch. It was found that these hydrocolloids significantly enhanced the water absorption while reducing the swelling power and solubility. Only pectin was found to be an effective gum which reduces the syneresis of the cowpea starch gel during freeze-thaw process. The results indicated that guar gum caused a noticeable increase of peak viscosity as well as viscosity at 95 degrees C examined by viscoamylograph whereas reducing trend was observed for both peak viscosity and viscosity at 95 degrees C when pectin was added. It was also observed that guar gum caused a rapid rise in viscosity during the cooling period whereas the addition of the xanthan as well as pectin dropped the viscosity of cowpea starch. The heating stability of cowpea starch was found to be reduced by the addition of guar and xanthan gums while set back capability was successfully reduced by all selected hydrocolloids. The firmness of cowpea starch gel could be improved by the addition of all selected hydrocolloids during storage as compared to native starch.