PHYSICAL, CHEMICAL AND FUNCTIONAL CHARACTERIZATION OF STARCH ROM Manihot esculenta MODIFIED WITH Terminalia mantaly GUM

Abstract

Starch extracted from the roots of Manihot esculenta and its composite blends with gum from Terminalia mantaly were studied for their physical, chemical and functional properties using standard experimental procedures. The proximate analysis of the starch gave values of 15.04 %, 84.96 %, 1.202 %, 0.97 %, 1.15 %, 0.635 %, and 96.655 % for moisture, dry matter, crude protein, ash, crude fibre, crude fat and carbohydrate respectively. The energy value was 394.715 Kcal/100 g. The amylose and amylopectin contents of the starch were 19.655 and 66.085 % respectively. There were significant differences in the water and oil absorption capacities, swelling power, solubility index, bulk/particle density and foaming capacity of the free starch and its blends while there were no significant differences in their gelation temperature and least gelation concentration. The peak and trough viscosities ranged from 399.08 (starch/gum ratio of 3.0:0.25) to 376.58 RVU (starch/gum ratio of 3.0:1.0) and 78.67 (starch/gum ratio of 3.0:0.25) to 115.58 RVU (starch/gum ratio of 3.0:1.0) respectively. Final viscosity ranged from 133.08 (starch/gum ratio of 3.0:0.25) to 187.83 RVU (starch/gum ratio of 3.0:1.0) while the pasting temperature and time ranged from 73.45 to 76.00 ? and 3.33 to 3.67 min, respectively. The morphology of the starch granules (size and shape) was studied with scanning electron microscope (SEM), which revealed that M. esculenta free starch showed asymmetric and irregular shaped granules with primarily ellipsoid and oval shapes. The modified starch showed oval, truncated and spherical granules. These variations in morphology of the granules could be attributed to the modification with T. mantaly gum as well as the biological origins of both the M. esculenta starch and the gums. Generally, there were improvements in the functional properties of the starch after modification.