# Non-Thermal Technologies in Food Processing: Implications for Food Quality and Rheology
## 7 Utilisation of Non-Thermal Food Processing Technologies
### Non-Thermal Technologies in Liquid Foods  
One of the most widely used non-thermal technologies for liquid food processing is PEF treatment. Due to the bulk nature of the food material being treated and the energy loss associated with using conventional heating methods for microbial inactivation in liquid foods like fruit juices and milk, a PEF is considered environmentally friendly and an energy saver [64]. Compared to conventional heat pasteurisation, a PEF requires a lower energy input and preserves heat-sensitive bioactive compounds such as vitamins, antioxidants, and enzymes that would otherwise degrade at high temperatures [19]. Also, its extended applicability makes it more popular. It can assist with extracting bioactive compounds from foods and waste polarisation [6; 45; 186]. One of the main issues associated with using a PEF is the requirement of a high capital investment as the entire setup for PEF technology needs various machinery and expertise, and because the technology is not easy to scale up [5; 6; 187]. However, with recent progress in the miniaturisation of the technology and improving its ease of use, a PEF promises to be a practical alternative to many conventional health processes in the coming years. Similarly, HPP technology is another non-thermal approach utilised for liquid food preservation treatments. Its utilisation reduces preservatives and has proven to be more economically viable than conventional methods. Although the process is not exactly suitable for porous and dehydrated foods, its benefits transcend food preservation as the process increases the food quality, such as increasing the content of key nutritional factors in food, e.g., the vitamin C concentration in juices [186; 188; 189; 190; 191; 192]. Although HPP consumes more energy than a PEF, it offers improved microbial reduction and decreased reliance on additives, making it more economically viable in the long term [80; 88]. PL and UV irradiation are also widely applied in liquid food treatment. These technologies are eco-friendly and, among other non-thermal processes, show the best results in maintaining the food texture, taste quality, and appearance [193; 194]. They are also highly effective for microbial inactivation and require a relatively low energy input. UV light, for instance, has been found to inactivate chlorine-resistant pathogens such as _Cryptosporidium parvum_ and _Giardia_ sp., leading to its wide adoption in the water industry [195]. Beyond water treatment and microbial inactivation in food surfaces, UV treatment has been reported to enhance the toxicological safety of food items such as the reduction of patulin mycotoxin in fresh apple cider [196] and the reduction of the allergenicity of liquid peanut butter [197]. Compared with conventional chemical treatments such as chlorine-based disinfection, UV has the advantage of being a non-chemical treatment, thereby reducing the issue of residual contaminants or the formation of toxic byproducts. Apart from its added advantage of being efficient for the inactivation of microorganisms in liquid food, it is ecologically friendly since it is free of chemicals and does not produce by-products [198]. However, the activity of UV light in liquid food systems may be influenced by turbidity and absorption profiles, which may require optimisation in some food matrices [12; 198]. PL sterilisation can overcome the challenge of UV light's poor penetration depth to some extent due to its broader spectrum of light, emission power, and higher penetration depth [143]. Also, considering that the energy utilised in PL sterilisation is multiplied manifold, it has the added advantage of being more effective and rapid for microorganism inactivation than continuous UV light [143; 198]. While the power emissions from a continuous UV light system range from 100 to 1000 W, a PL system can provide a peak power distribution as high as 35 MW [143].