Optimization and digestogram modeling of hydrothermally modified elephant foot yam (Amorphophallus paeoniifolius) starch using hot air oven, autoclave, and microwave treatments

Abstract

Native elephant foot yam starch (EFYS) is easily susceptible to enzymatic hydrolysis and becomes harmful for diabetes and obese patients. To address this issue, heat moisture treatment (HMT) using various heating sources viz. hot air oven (HAO), autoclave (AL), and microwave (MW) were employed to modify EFYS. Response surface methodology was used to determine optimum treatment conditions viz. time (min), temperature (°C), microwave power (W), and moisture content (g/100g) of the mentioned modification processes. Rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) were the responses for the optimization process. The highest increment in RS was observed from 29.88 mg/g to 54.98 mg/g in HAO EFYS among all the modified EFYS. Regression analysis showed that predicted quadratic models fitted well with the experimental data and was significant (p < 0.05) with R2 ≥ 0.9 for all responses. Besides, swelling volume showed an insignificant change, but a substantial reduction in whiteness index, swelling power, and solubility was observed. Decrease in digestion rate was observed in modified EFYS in comparison with native EFYS. The study revealed that the Paolucci Jeanjean model (R2 = 0.991) was the best fit for the experimental data of the starch digestogram.