Structure, physicochemical and in vitro digestion properties of ternary blends containing swollen maize starch, maize oil and zein protein

Three-component blends (TCBs) were prepared with maize starch (MS), maize oil (MO) and zein protein (ZP) through high-speed homogenization and heat treatments. The objective of this study was to understand the thermal treatment effect on the structural, physicochemical and digestion properties of the TCBs, providing guidance for designing low GI foods with higher slowly digestible- and resistant- starch. From the images of confocal laser scanning and scanning electron microscopy, ZP was mainly located on the surface of starch granules. Thermal analysis showed that a decreased enthalpy change is associated with higher treatment temperature due to the loss of the double helices of amylopectin. The high-speed homogenization and heat treatments changed the X-ray crystalline pattern of starch from the A-type to a mixture of the A- and V-type pattern. The TCBs displayed a decreased peak viscosity and an increased pasting temperature, compared with the MS alone. For the first time, we demonstrated that heating treatment at 40 °C can result in the lowest rapidly digestible starch fraction for both uncooked and cooked TCBs.