Comparison Study of DBD Plasma Combined with E-Beam Pre- and Post-treatment on the Structural-Property Improvement of Chinese Yam Starch

Abstract

The study is aimed at investigating the effect of dielectric barrier discharge (DBD) plasma and E-beam technology modification sequences on the “structure property” of starch. Here, DBD plasma (treated with 1 and 5 min) and E-beam (irradiated under 5 and 10 kGy) and their pre-/post dual modifications were applied to characterize the structural and physicochemical properties of starch. Although plasma causes etching on the starch surface, E-beam poses a minor effect on microstructure. Both modifications promoted starch degradation, resulting in substantial molecular weight, long chain proportions, and viscosity reductions. Also, the short-range ordered structure and the relative crystallinity of starch were disrupted after both modifications. Nevertheless, starch FT-IR spectrum patterns, crystal types, and growth rings were retained. In addition, both treatments improved native starch solubility and suppressed swelling power. Interestingly, plasma-E-beam (P-E) treatment induced a deeper modification degree of starch at the same treatment intensity than E-beam-plasma (E-P) treatment, as evidenced by lower molecular weight and viscosity, smaller R_1047/1024, and enthalpy. For resistant starch (RS) content, P-E treatment provided a more intensive improvement. Consequentlys, we suggest pre-plasma treatment in starch processing since it improves the viscosity, solubility, and digestibility of native starch with less damage to the starch structure.