# Non-Thermal Technologies in Food Processing: Implications for Food Quality and Rheology
## 2 Pulsed Electric Field (PEF)
The resulting structural improvements enhanced the functional qualities of flour, evidenced through the higher level of gluten aggregation energy (19-29%) and dough viscosity (18-43%) upon blending wheat flour with PEF-treated oat or barley flour. However, PEF treatment also induced a reduction in the specific volume (11-24%) of the final bread product. Scanning electron microscopy (SEM) demonstrated the pronounced microstructural alteration of barley proteins, further validating the PEF's impact on the flour structure, which affirms PEF's efficacy to modulate the enzymatic activity and manipulate the polysaccharide structures [74]. Furthermore, it is well known that consumers generally enjoy liquid/pastry food products based on their rheological and colour characteristics. Using a controlled stress rheometer with shear rates ranging from 0 to 200 s\({}^{-1}\), the evaluation of the effects of pulsed electric field (PEF) treatments with an electric field intensity of 18, 20, and 22 kV cm\({}^{-1}\) and number of pulses of 25, 50, 75, and 100 on the colour and rheological characteristics of soy milk was carried out [75]. In this study, the flow behaviour, viscosity, and rheological parameters of PEF-treated soy milk were observed. The results showed that the apparent viscosity of soy milk increased from 6.62 to 7.46 (10\({}^{-3}\) Pa s), with an increase in the electric field intensity from 18 to 22 kV cm\({}^{-1}\) and increase in the number of pulses from 0 to 100. Shear-thinning behaviour and an increase in the apparent viscosity with the increasing electric field intensity and number of pulses are the results of PEF's effects on the flow behaviour and viscosity of reconstituted skim milk treated with electric field intensities of 15, 18, and 20 kV cm\({}^{-1}\) and numbers of pulses of 20, 40, or 60 [76]. In another study, the impact of PEF on the functional, rheological, and structural properties of vital wheat gluten were evaluated [77]. It was found that the elastic modulus, viscous modulus, tan \(\delta\) of the wet gluten protein, and the apparent viscosity of the vital wheat gluten changed significantly (\(p<0.05\)) with the increase in the electric field intensity. Consequently, the PEF treatment showed a significant impact on the gluten protein properties to various extents. This implies that PEF processing affected the rheological properties of soy milk. Hence, depending on the electric field intensity and number of pulses, PEFs, a non-thermal alternative technology, have the potential to affect the quality, sensory, and nutritional qualities of food products while also inactivating spore-forming bacteria and extending their shelf life. The PEF's effects on the rheological, structural, and physicochemical characteristics of almond milk showed that, following PEF treatments, the viscosity and nonenzymatic browning significantly decreased while the electrical conductivity, cloud value, and cloud stability significantly increased [78]. The changes in the nutritional qualities and rheological properties of red raspberry (_Rubus strigosus_) and blueberry (_Vaccinium corymbosum_) pures were studied based on treatment with a PEF in continuous, ultrasonication (US), and combined methods [79]. The results prove that only US and combined methods were capable of inactivating polyphenol oxidase (PPO) at a significant level (\(p<0.01\)). However, ultrasonication (US) caused a significant change in the rheology of the pures, especially in blueberry, revealing a gradual shift from a non-Newtonian to Newtonian model, complemented with a decline in the apparent viscosity. Hence, microstructure development, quality control, sensory analysis, and process equipment design all benefit greatly from the evolution of rheological properties in relation to food processing conditions. Nonetheless, non-thermal technologies are appropriate for treating berries due to their improved nutritional quality; however, the process design should consider changes in rheological properties [79].