Enhancing functional and nutritional quality of soy protein using plasma-liquid interface

Soy protein, a prominent plant-based protein, contains antinutritional factors that reduce nutritional value and digestibility. Cold plasma (CP) technology is an eco-friendly alternative, operating at low temperatures with minimal chemical input. A plasma-liquid interface is the boundary region where plasma comes into direct contact with a liquid, characterized by complex physico-chemical interactions including charge and species transport, and unique surface phenomena. These offer a promising approach for protein modification by utilizing reactive species. This study investigates the impact of plasma-liquid interface on soy protein's functional properties and antinutritional factors, aiming to improve overall product quality. 2% of soy protein solutions were treated with a jet plasma (Plasma Leap Technologies, Sydney, Australia). Samples were treated with air and argon. Plasma parameters were set to 125V, 1.5 kHz frequency, 80 µs duty cycle, and 1-10 minutes treatment time. Solubility, emulsification, foaming, digestibility, antioxidant activity, antinutrient inhibition such as trypsin inhibitor and phytate, lipoxygenase, and lipase activity were assessed. The cold plasma treatment significantly affected the functional qualities of soy protein, such as solubility, gelation, emulsification, and foaming. The emulsion forming index showed a 0.15 increase and higher stability for 1 hour. The solubility showed no significant change, possibly due to plasma-induced structural alterations. The plasma exposure also significantly lowered the foaming capacity and stability. The digestibility was significantly improved by ~10%, and the samples showed better radical scavenging activity. Additionally, it reduced antinutritional factors like phytates, with the maximum reduction observed at 6 minutes treatment. The evaluation of lipase and lipoxygenase activities is underway, with preliminary results showing positive reduction. The research highlights plasma-liquid interface as a promising method for enhancing soy protein's functional, nutritional, and storage attributes without the drawbacks of conventional processing techniques.