Effect of acid–methanol treatment on the molecular structure and physicochemical properties of lentil (Lens culinaris Medik) starch

The effect of acid–methanol treatment using 0.36% HCl in methanol at 25 °C for 4–216 h on molecular structure and physicochemical properties of lentil starch was investigated. The recoveries for modified starch granules were quite high (91.9–95.6%). Upon modification, the starch granules showed formation of cavities, surface roughness and development of protuberances. The solubility of lentil starch increased, while swelling power, pasting viscosity and gel strength decreased with increase in treatment duration. These changes were found to be due to preferential degradation of amylose and amylopectin long chains in acid–alcohol treatment, which was confirmed by studies conducted on high-performance size-exclusion chromatography (HPSEC). Data obtained from HPSEC was also used to develop an exponential model to illustrate the degradation kinetics of acid–methanol-treated lentil starch.