Effect of Physical Dual-field Coupled Enzymolysis on Phenolics Solubilization and Viscosity of Flaxseed Plant-based Milk

In order to investigate the impact of physical field-coupled enzymatic treatments on flaxseed plant-based milk, this investigation was conducted in a phased manner. Firstly, cellulase was modified by using low temperature plasma treatment (cold plasma) to increase its enzyme activity, and the optimal treatment time was determined based on the results of enzyme activity changes, and then the structural alterations of the enzyme were characterized using fluorescence spectroscopy, ultraviolet spectroscopy, and circular dichroism spectra (CDs) to explore the mechanism of enzyme activity changes. Secondly, this study probed the influence of cold plasma (CP) or pulsed electric field (PEF) respectively, when coupled with enzymatic treatment, on the solubilization of phenolic compounds and the rheological properties of flaxseed plant-based milk, and according to the experimental results, the optimal PEF treatment voltage was determined. Finally, the flaxseed plant-based milk was treated with CP (time: 15 seconds) and PEF (voltage: 3.7 kV/cm) coupled with cellulase to assess the effectiveness of the cold plasma and pulsed electric field coupled enzymatic treatment (CP-PEF-EN) on the total phenolic content and viscosity of flaxseed plant-based milk. The findings revealed that the enzymatic activity of cellulase exhibited an initial surge (up to 89% at 15 seconds) followed by a decline upon CP treatment. Spectroscopic analyses indicated that the reactive ions generated by CP interacted with the enzyme molecules, leading to alterations in the enzyme's catalytic sites and functional groups. Additionally, the enzyme's secondary structure was changed, from an initial increase and subsequent decrease in β-sheet content. The results demonstrated that both CP and PEF single-field coupled enzymatic treatments could enhance the total phenolic content of flaxseed plant-based milk (increase rates were 44.44% and 46.97%, respectively). Notably, the CP-PEF-EN proved more efficient, increasing the total phenolic content to 0.327 g/100 g (a 65.15% increase) and reducing the viscosity to 77.47 mPa·s (a 39.92% decrease). This study underscores the potential of CP-PEF-EN treatment to significantly increase the total phenol dissolution rate and mitigate the viscosity of flaxseed plant-based milk, providing a reference for the processing technologies of innovative eco-friendly plant-based milk.