# Non-Thermal Technologies in Food Processing: Implications for Food Quality and Rheology
## 2 Pulsed Electric Field (PEF)  
PEF is a modern food processing method which employs an electric field instead of heat for food processing. Varying voltage pulses, from 10 to 80 kV/cm, are applied to foods for a few seconds using two (2) electrodes inserted in the food products [19; 50; 51]. As demonstrated in Figure 1, a typical PEF system consists of a control and monitoring system along with an electric power source, pulse initiator, assembly room, and cooling systems. These ensure the optimum control of the unit. PEF systems generate a minimum amount of heat (40 \({}^{\circ}\)C) [6; 52; 53; 54]. The main mechanism of action of the PEF is an electrical breakdown and electroporation within the food matrix and any microbial agent present [55; 56; 57; 58; 59]. Electric energy is passed through the food with the aid of an electric charge. Electroporation produces holes in the cell wall and inner cell of microbes, which inactivate the microorganism. After electroporation, the electrical breakdown processes weaken the pathogen's cell membrane. As a result, the cell cytoplasmic contents tend to leak and the death of microorganism cells occurs [3]. The efficiency of PEF treatment depends on the rate of conductivity, field strength, PH, nature of food to be preserved, time, temperature, and pulse energy. In preserving apple, orange, pea soup, eggs, milk, and milk products, the PEF is mostly used as this process helps improve the rheological and antioxidant aspects of juices [6; 52; 53; 58; 59; 60; 61; 62]. Food pasteurisation using conventional thermal processes has been employed for a long time to achieve food safety. Nowadays, the Pulsed Electric Field (PEF) technology has increasingly been adopted as an alternative to thermal processes in the food industry, particularly in the production of fruit juices, dairy products, and liquid egg processing [63; 64]. The main advantage of the pulsed electric field method is that it can increase the shelf life of liquid foods. During this process, organoleptic properties remain the same, as in the original liquid. In the last 50 years, the PEF method has been used on a large scale for pasteurisation in various industries including the diary and fruit juice industries, using large chambers and power supply equipment [24]. However, the application of PEF in solid foods is still emerging, unlike in liquid food processing, due to challenges related to uniform electric field distribution and the efficacy of microbial inactivation [65]. Researchers have reported that high-intensity pulsed electric field processing successfully achieves long-life fresh fruit juices and beverages [66; 20]. However, since low-intensity PEF treatment is not very effective against most microbial species, the direct application of PEF for the preservation of solid foods is still not feasible [67]. Nevertheless, the electroporation effect induced by PEF enhances the mass and energy transfer, and thereby makes it highly appropriate for application as a pretreatment prior to drying, cooking, and freezing operations [65]. PEF technology significantly impacts food rheology by maintaining food components' structural integrity and functional properties during processing. It ensures minimal alteration to the viscosity of liquid foods such as juices while preserving essential bioactive compounds. The process enables effective pasteurisation without thermal damage, retaining the sensory attributes and nutritional value of products such as milk and beverages. The PEF has been associated with the better retention of colour in plant-based products, such as orange juice, due to its mild effect on pigments like carotenoids and chlorophyll, hence yielding more stability and homogeneity [68]. [PERSON] et al. [69] made a comparison of high-intensity pulsed electric field (HIPEF) processing and traditional heat  
Figure 1: A schematic illustration of a typical Pulsed Electric Field (PEF) operation [20].