Effect of Combined Heat-Moisture/Lactic Acid Treatment on the Physicochemical and In Vitro Digestibility Properties of Corn Starch

Native corn starch is subjected to dual heat moisture (30 g per 100 g d.b.)/lactic acid (10 g per 100 g d.b.) treatment (HMLAx) at different temperatures (x= 90, 110, 130, and 150 degrees C), and is compared with heat moisture (HMx) treatment alone. Neither HMLAx nor HMx change the crystallinity type (A-type) of the corn starch, but the relative crystallinity is lowered by 60-80%. Both treatments reduce the gelatinization enthalpy, but it is higher for HMLAx (approximate to 70%), and induces reductions in rapidly digestible starch (up to approximate to 70%) and increases in slowly digestible starch (up to approximate to 35%) and resistant starch (RS) fractions. The variations are temperature dependent. A principal component analysis is carried out (9 formulations, 17 variables), showing that heat moisture and lactic acid act independently (p< 55%) in the modification of starch, giving rise to different physicochemical (solubility, viscoelasticity, relative crystallinity), thermal, and in vitro digestibility properties.