Effect of Heat-Moisture Treatment of Pigeon Pea (Cajanus cajan) on the Quality of Its Starch

Heat–moisture treatment (HMT) provides a physical approach to modifying starch properties for food applications. This study evaluated its effects on the composition, functional properties, and pasting characteristics of pigeon pea starch. Starch was extracted at a yield of 21% and treated at 110 °C for 3 h at 30% moisture content. Unmodified and modified starches were evaluated for amylose content, proximate and mineral composition, color, and functional and pasting properties using standard methods. HMT significantly increased protein, fat, fiber, ash, and moisture contents (p < 0.05), while decreasing carbohydrate content and energy value. Protein content increased from 6.63% to 8.02%, whereas carbohydrate content decreased from 81.48% to 78.49%. Phosphorus, calcium, iron, magnesium, potassium, and sodium contents increased following treatment, and amylose content rose from 12.76% to 13.21%. HMT reduced lightness from 87.48 to 81.56 and increased redness from 2.33 to 4.50 and yellowness from 9.48 to 11.39. Treatment significantly decreased bulk density, water absorption capacity, foaming capacity, swelling power, and solubility, while increasing oil absorption capacity, dispersibility, and foaming stability. Oil absorption capacity increased from 1.0 to 1.5 g/g, dispersibility from 79.00% to 82.00%, and foaming stability from 92.18% to 97.16%. HMT also significantly reduced peak, trough, breakdown, final, and setback viscosities. Peak viscosity decreased from 3861.00 to 1165.00 RVU, and final viscosity declined from 4628.00 to 1622.50 RVU. Conversely, peak time increased from 5.15 to 7.00 min, and pasting temperature increased from 84.45 to 92.00 °C. These findings demonstrate that HMT alters the compositional, functional, and pasting characteristics of pigeon pea starch, supporting its potential as a physical modification strategy for tailoring starch properties for food applications.