Main content area

Effect of acid hydrolysis on rheological and thermal characteristics of lentil starch slurry

Ahmed, Jasim, Auras, Rafael
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2011 v.44 no.4 pp. 976-983
acid hydrolysis, gel strength, gelatinization, hydrolysis, lentils, modulus of elasticity, process energy, reaction kinetics, slurries, starch, starch gels, temperature
A comparative rheological and thermal study was carried out between acid hydrolyzed and unhydrolyzed (control) lentil starch dispersions (25–33.3 g starch per 100 g water) as function of temperature. After acid hydrolysis, the peak gelatinization temperature (Tₚ) shifted to higher temperature than the corresponding starch without hydrolysis whereas the gelatinization enthalpy remained unaffected by hydrolysis. The starch gelatinization kinetics was evaluated by a non-isothermal technique as function of elastic modulus (G′) and G′ vs. time (t) data up to the gelatinization peak value was considered for rate estimation. A 2nd-order reaction kinetics described well the starch gelatinization process and the process activation energy was ranged between 241 and 434 kJ/mol. Acid hydrolysis strongly affected the rheological properties by lowering gel strength compared to unhydrolyzed starch. The creep analysis further revealed that starch gel was significantly affected by hydrolysis and exhibited less resistant to the stress. A 4-parameters Burgers model well-described creep curves and supported oscillatory rheological data.