Effect of Atmospheric Pressure Argon Plasma on Physicochemical, Structural and Rheological Properties of Sorghum Starch

Nonthermal plasma is a physical method of starch modification. In this study, sorghum starch is subjected to dielectric barrier discharge (DBD) argon plasma at voltage levels of 21 and 29 kV for 1, 10, and 20 min. Plasma etching creates more pores on the surface of starch granules. Fourier transform infrared spectroscopy shows that low intensity of plasma causes crosslinking of starch molecules, while longer time or higher voltage suppresses crosslinking and increases depolymerization. The plasma treatment of starch for 1 min decreases the clarity, while an increase in the time or voltage rises clarity. The swelling power of treated starch is higher than that of untreated one. By an increase in time or voltage, the solubility of untreated starch (16.95%) increases (up to 33.47%). After 1 min of treating starch, the viscosities of the paste increases, but then decreases with increases in voltage or time. According to the frequency sweep test, the gels of 1-21, 10-21, and 1-29 samples are stronger than those of the other samples and have greater complex viscosities than them. It can be concluded that DBD argon plasma can produce cross-linked and depolymerized starch depending on different voltage and time of treatment.

Automated summary

Nonthermal plasma can modify starch properties by creating more pores on the surface of starch granules through plasma etching. The treatment can induce crosslinking or depolymerization of starch depending on the time and voltage. The treated starch shows increased clarity, swelling power, and solubility compared to untreated starch.