APPLYING NON-THERMAL PLASMA TO MODIFY STARCH PROPERTIES

Several methods, especially chemicals, are used to modify native starches properties to expand their applications in the food industry. However, physical treatments, such as non-thermal plasma (NTP), can also be potentially successful for this purpose. The present study aimed to evaluate the effect of NTP treatment on the technological properties of corn (C), cassava (CS), and potato (P) starches. These samples were treated during 40 min in afterglow microwave-discharged NTP at atmospheric pressure, with a power of 200 W, and argon gas flow of 10L/min. Optical microscopy, moisture, color, pH, damaged starch, pasting properties, and gel strength analyses were performed, and the data were evaluated by t-test (p<0.05). When the treated samples were observed in polarized light under the microscope, it was possible to identify their birefringence. Notably, only potato starch showed fissures on the granule surface after treatment. The moisture content was reduced in the medium of 13.18% in treated samples (C: 12.17 to 10.66%; CS: 12.23 to 10.38%; P: 12.93 to 11.38%) as a result of the disruption of bound water molecules from the starch. Regarding pH and color parameters, there were no significant differences between treated and untreated samples. It was observed an increase in the damaged starch content of 10.53% in corn (4.37 to 4.83%) and 7.06% in potato (4.25 to 4.55%) starches, which will directly influence the hydration rate and enzymatic activity of the material. The NPT treatment changed starches pasting properties, especially decreasing setback. For gel strength, cassava and potato starches required a higher force for gel disruption (CS: 0.30 to 0.37N; P: 1.01 to 1.20N), probably due to cross-linking of starch molecular chains, giving rise to a more cohesive and structured gel network. Therefore, NTP can be an efficient alternative technology to chemical modification starches, inducing interesting modifications, without waste generating.