Effect of Atmospheric Pressure Cold Plasma Treatment on the Radical Scavenging and Antioxidant Activities, Phenolic Content, and Some Nutritional Characteristics of Chia Seeds (Salvia hispanica L.)

This study investigates the potential effects of atmospheric pressure cold plasma (ACP) treatment as a novel nonthermal processing method for plant-derived products, specifically focusing on chia seeds, a rich source of nutrients. The impacts of ACP treatment (at intensities of 6.5 kV for 3 min, 6.5 kV for 8 min, 8.5 kV for 3 min, and 8.5 kV for 8 min, which are called S1, S2, S3, and S4, respectively) on radical scavenging and antioxidant activities, phenolic content, and some nutritional characteristics of chia seeds were examined and compared with the control sample (untreated sample). Results indicated that the quantities of fat, ash, crude fiber, and carbohydrate changed on the basis of ACP treatment intensity (i.e., exposure time and the voltage applied during the treatment), suggesting that the intensity and effects of plasma-activated species play a key role in this process. In terms of in vitro starch digestibility, a significant increase was observed, from 40.14% in the control to 64.99% in the sample treated for 8 min at 8.5 kV (designated as S4). A similar trend was noted for in vitro protein digestibility, which increased from 68.39% in the control to 85.54% in S4. These improvements are attributed to the depolymerization and side-chain cleavage induced by plasma-activated species during ACP treatment. Moreover, ACP treatment led to an increase in both polyphenol content and antioxidant activity. Polyphenol content rose from 41.59 mg GAE/g in the control to 64.98 mg GAE/g in S4, while antioxidant activity increased from 68.39% to 85.45%. The enhancement in antioxidant activity may also be partly due to UV radiation generated during plasma production, which can stimulate the formation of secondary metabolites. Overall, the findings demonstrate that the effects of ACP treatment on the various parameters examined—such as proximate composition, digestibility, phenolic content, and antioxidant activity—are influenced by exposure time and voltage. These variations appear to be primarily driven by the action of plasma-activated species.