Turmeric Powder and Starch: Selected Physical, Physicochemical, and Microstructural Properties

  Turmeric powder and its starch were characterized for physical, physicochemical, and microstructural characteristics. X‐ray diffractogram indicated that turmeric starch to be of B type. Dried and cured‐dried turmeric powder samples showed higher water‐holding capacity (3.62 and 4.78 g/g, respectively) compared to isolated starch (1.07 g/g) at 30 °C. Non‐Newtonian shear‐thinning characteristics were observed with turmeric powder dispersion containing 10% (w/w) solids. A power law model fitted well to correlate the shear‐rate and shear‐stress data ( r = 0.993 to 0.999, P ≤ 0.01) for both samples. Apparent viscosities of isolated turmeric starch and cured‐dried turmeric powder dispersion containing 10% (w/w) solids were 1.29 ± 0.03 and 7.57 ± 0.39 mPa s, respectively. Microstructure of starch particles showed a smooth flat outer surface. The approximate length and breadth of isolated elliptical starches were 25 and 10 μm while the thickness was about 5 μm. Practical Application:  Isolation and characterization of starch from an unconventional source like turmeric rhizome indicate a potential application as a functional ingredient in foods and pharmaceutical industries including agglomerated products.