# Non-Thermal Technologies in Food Processing: Implications for Food Quality and Rheology
###### Abstract  
The food industry mostly utilises thermal processing technologies to enhance the food safety and shelf life by inactivating enzymes, pathogens, and spores. However, there is a shift towards consumer preference for minimally processed foods due to health concerns and the limitations of the conventional thermal processing methods. Thus, the food industry has recently increased the utilisation of non-thermal technologies for food processing and preservation in the production of foods while maintaining the nutritional and sensory qualities of the food. Non-thermal approaches including a Pulsed Electric Field (PEF), High-Pressure Processing (HPPP), Ionising Radiation (IOR), Ultraviolet (UV) light, Pulsed Light (PL), and Cold plasma (CP) are increasingly being employed for food preservation, especially for heat-sensitive foods, as they enable microbial inactivation with minimal or no thermal application and less degradation of bioactive constituents of foods. As opposed to conventional thermal technologies that may compromise the food quality, non-thermal preservation processes retain the texture, taste, and rheological properties, therefore presenting an invaluable option in the food chain system. Moreover, non-thermal food processing approaches are becoming well-established within the food sector as they can be utilised for a wide range of food items. This paper provides a critical review of the industrial applications, mechanisms of action, and efficiency of major non-thermal food processing technologies. In addition, it also addresses their impact on the food quality, microstructure, and rheology, while exploring their limitations. Although these technologies are of great value in preserving the shelf life and food integrity, high upfront investment costs continue to discourage large-scale adoption. However, with the growing demand for fresh and minimally processed foods, the operational costs for these technologies are expected to become more accessible, promoting their widespread adoption in the industry. fluid flow; food rheology; non-thermal food processing; product development; food preservation; food processing techniques +
Footnote †: journal: Applied sciences
the elimination of spoilage and food-poisoning pathogens [1]. These developments within the agro-sector have improved the safety of foods and are geared towards meeting the demands of consumers for fresh and minimally processed healthy foods with a prolonged shelf life [2; 3; 4; 5]. To fulfil these new consumer requirements, old thermal processes will be phased out in the near future [6]. Generally, high-temperature heating systems utilised in food preservation negatively affect the nutritional value and sensory properties of foods, such as the degradation of heat-sensitive vitamins (e.g., vitamin C), a loss of essential amino acids, and alterations in the texture, colour, and flavour [7]. The main purpose of heat processing technology is to reduce the multiplication of microorganisms and the deterioration of food [8]. New technologies are designed to inactivate microorganisms and maintain other sensory aspects and nutritional values of foods without the application of extreme heat [5; 9]. For example, the most common and straightforward method for preserving liquid foods is to use an ultra-high temperature (UHT) or high-temperature short-time (HTST). However, the drawback of this method is that it results in enzyme inactivation, useful proteins are denatured, and vital vitamins are lost [10]. Also, a large amount of energy is consumed by heating, which is not cost-effective, especially in large-scale food production [11]. Recent research in food processing and preservation is targeted at the development of non-heating methods to produce safe processed foods while inactivating microorganisms and being energy efficient, with the overall drive to produce an environmentally friendly product [12; 13]. Several non-thermal approaches are available currently and with applications in the food industry.