Comparison of in Vitro Digestibility and Physicochemical Properties of Corn Starch-soy Protein Isolate/Ovalbumin Complexes
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Abstract:
In order to reduce the digestion rate of corn starch (CS) and increase the content of resistant starch (RS), this study used heat moisture treatment (HMT) to prepare starch-protein complexes by combining CS with a soy protein isolate (SPI) or ovalbumin (OVA). The effects of the mass fractions of proteins (5%, 10%, 15%, and 20%) on the physicochemical, rheological, and digestive properties of the starch-protein complexes were studied. Differential scanning calorimetry and dynamic viscoelasticity revealed that the swelling of starch granules was limited by the addition of proteins. X-ray diffraction data showed that the crystallinity of corn starch decreased from 28.75% to 24.92% and 25.29% after the addition of SPI or OVA, respectively. Scanning electron microscopy showed that the added proteins wrapped around the starch granules and acted as a physical barrier inhibiting starch digestion. Moreover, in vitro digestion analysis showed that SPI and OVA additions lowered the rapidly digestible starch (RDS) content of corn starch by 10.39% and 14.9%, respectively. In conclusion, addition of both proteins decreases starch digestibility, and the OVA has a stronger inhibitory effect on the digestibility of starch than SPI. The findings of this study provide insights for developing low glycemic index foods containing starch-protein complexes.
