Effect of microwave plasma power on the properties of pea starch: Granule morphology, gelatinization behavior, and gel properties

As a new non-thermal processing technology, microwave plasma (MP) has attracted much attention in the field of food processing due to its advantages of simplicity, green and high efficiency. The purpose of this study was to investigate the effects of MP power (60, 80 and 100 W) on granule morphology, gelatinization behavior and gel properties of pea starch (PS). The results indicated that with the increase of MP treatment power, more cracks and holes were generated on the surface of starch particles. FTIR showed that no new functional groups were produced in PS after MP treatment, while the disorder of the starch structure increased. XRD analysis showed that the C-type pattern of starch did not change, but the relative crystallinity (RC) decreased. Compared with PS, the solubility (13.26 ± 0.73 % to 15.93 ± 0.89 %, 90 °C), swelling power (8.68 ± 0.60 g/g to 10.26 ± 0.23 g/g, 90 °C) and hydrolysis degree (63.35 ± 0.98 % to 70.39 ± 0.30 %) of PS treated with MP were significantly increased. However, the amylose content (AM, 27.90 ± 0.01 % to 23.42 ± 0.01 %), average particle size (27.01 ± 7.95 μm to 24.75 ± 7.39 μm) and gelatinization temperature (PT, 75.90 ± 0.06 °C to 73.36 ± 0.10 °C) decreased. When the MP treatment power was 80 W, the cross-linking and depolymerization of starch chains were the most significant, and the gelatinization behavior was obvious. Meanwhile, proper MP treatment made it easier to produce low-viscosity, soluble, and stable starch gels. These results provide both a new modification method for the application of PS and a theoretical basis for the development of pea starch-based products.