Physicochemical, Pasting, and Thermal Properties of Native Corn Starch-Mung Bean Protein Isolate Composites

Starch is widely used in food and non-food industries because of its unique characteristics. However, native starch shows some weaknesses that restrict its applications. Recently, some studies have demonstrated the benefits of using protein to overcome these limitations. Therefore, the aim of the present study was to investigate the effect of mung bean protein isolate (MBPI) (2%, 4%, 6%, and 8%) on the physicochemical, pasting, and thermal properties of native corn starch (NCS), as a novel starch-protein composite. Higher swelling power (SP), water absorbance capacity (WAC), and solubility values of NCS were observed with increasing MBPI concentration. Additionally, by the addition of MBPI, the rapid visco analyzer (RVA) showed a reduction in pasting temperature (77.98 to 76.53 degrees C), final viscosity (5762 to 4875 cP), and setback (3063 to 2400 cP), while the peak viscosity (4691 to 5648 cP) and breakdown (1992 to 3173 cP) increased. The thermal properties of NCS/MBPI gels investigated by differential scanning calorimetry (DSC) showed higher onset, peak, and conclusion temperatures (69.69 to 72.21 degrees C, 73.45 to 76.72 degrees C, and 77.75 to 82.26 degrees C, respectively), but lower gelatinization enthalpy (10.85 to 8.79 J/g) by increasing MBPI concentration. Fourier transform infrared spectroscopy (FT-IR) indicated that the addition of MBPI decreased the amount of hydrogen bonds within starch. Furthermore, after three cycles of freeze-thaw shocks, the syneresis of NCS-MBPI composites decreased from 38.18 to 22.01%. These results indicated that the MBPI could improve the physicochemical properties of NCS, especially its syneresis and retrogradation characteristics.

Automated summary

The aim of this study was to investigate the effect of mung bean protein isolate (MBPI) on the physicochemical, pasting, and thermal properties of native corn starch (NCS). The results showed that increasing MBPI concentration led to higher swelling power, water absorbance capacity, and solubility of NCS. Additionally, the addition of MBPI lowered the pasting temperature, final viscosity, and setback, while increasing the peak viscosity and breakdown. The thermal properties of NCS/MBPI gels exhibited higher onset, peak, and conclusion temperatures, but lower gelatinization enthalpy, with increasing MBPI concentration. Fourier transform infrared spectroscopy (FT-IR) analysis indicated a decrease in hydrogen bond content within starch upon addition of MBPI. Furthermore, the freeze-thaw shock test showed reduced syneresis in NCS-MBPI composites.