Assessment of nutritional, physicochemical, antioxidant, structural and rheological properties of spray dried tamarind pulp powder

Abstract

The present study was aimed to evaluate the nutrient composition, physicochemical, antioxidant, structural and rheological properties of spray dried tamarind pulp powder (TPP). Proximate composition of TPP showed 2.62% moisture, 21.69%, protein, 3.64% crude fiber, 1.69% ash, 70.28% carbohydrate and 0.08% fat. Mineral analysis revealed high potassium content (582.31 mg/100 g) followed by calcium (182.26 mg/100 g), phosphorous (117.82 mg/100 g), magnesium (65.95 mg/100 g) and sodium, (42.67 mg/100 g). Water activity, acidity, pH, hygroscopicity, solubility and dissolution time of TPP was 0.152, 9.37%, 2.59, 25 g/100 g, 71.95% and 19.87 s, respectively. Particle size analysis of the powder depicted bimodal particle size distribution with particle size ranging from 0.8 to 334 µm. Loose and tapped bulk density, and particle density of the powder was 0.39, 0.45 and 1.51 g/mL respectively. TPP showed good flowability, evaluated on the basis of Hausner ratio (1.16), Carr’s index (14.05%) and cohesion index (10.19 mm). TPP also possessed high total phenolic content (204.53 mg GAE/100 g) and radical scavenging activity (49.27%). X-ray diffraction of TPP revealed amorphous nature. FTIR analysis showed almost no change in molecular structure of TPP compared with ripe tamarind pulp but peak intensity varied. Reconstituted solutions of TPP (10–30% w/v) showed non-Newtonian shear thinning fluid behavior. Moreover, power law model successfully described the rheological properties of reconstituted tamarind pulp powder solutions.