## 1 Introduction  
Quality of fish and meat and other muscle food products depends heavily on processing and preservation methods applied after harvest or slaughter. Indeed, without adequate treatment and preparation, muscle food products undergo rapid natural deterioration due mainly to microbial growth, oxidative reactions, and enzymatic autolysis. That is why a wide range of preservation techniques have been developed over the years [1]. Traditional thermal treatments such as roasting, boiling, grilling, and frying have been widely used for ages due to their availability and simplicity. The main purposes of thermal treatments are to cook food and enhance sensory properties and digestibility, to inactivate microorganisms and ensure food safety, and to extend the shelf life [2; 3]. However, the application of high heat loads may lead to degradations and harmful effects on sensory and nutritional quality parameters of the treated products, especially in the case of muscle food products, which are known for their high sensitivity to heat treatments [4; 5; 6]. Muscle protein denaturation, lipid and protein oxidation, and loss in nutritional quality are among the well-known alterations that take place in muscle foods during thermal treatments [7; 8; 9]. Moreover, the constantly increasing consumer demand for fresh, safe, nutritious, and healthy food products, along with the novel consumption trends (e.g., minimally processed foods) have moved the food industry towards the development of novel and innovative thermal processing techniques [10; 11]. In this regard, a number of techniques, such as microwave, radio frequency, ohmic heating, and infrared processing have become the center of interest of several recent studies [2; 12; 13; 14]. Over the past few years, more advanced techniques have emerged aiming to meet consumer demands for high-quality products, with extended shelf life, improved safety, and enhanced process efficiency. With these in mind, a number of non-thermal treatments including, modified atmosphere packaging (MAP), high pressure processing (HPP), pulsed electric field (PEF), ultrasound (US), and cold plasma, among others [15; 16; 17; 18; 19; 20; 21; 22; 23] have grown in popularity over the last few years. Some of these techniques are already in use in the food industry, while others are still under development and require further improvement. Several studies have demonstrated that such preservation approaches are energy-efficient and allow inactivating microorganisms and enzyme activity in food products without compromising on their sensory quality attributes [10; 11; 15; 24; 25]. Extensive information about the application of non-thermal treatments in fish [15; 16; 26; 27] and meat [10; 28; 29; 30] can be found in the referred literature. On the other hand, most of the analytical methods used to assess changes in fish and meat during or after processing are based on sensory and microbiological analysis, as well as a number of physicochemical approaches [10; 31; 32]. Although sensory and microbiological measurements are among the most used techniques to determine the shelf life of most food products, these techniques are laborious and expensive as it usually takes from several hours to several days in order to obtain the results. Besides, the destructive nature of such measurements makes them unattractive for routine monitoring in the modern food industry. These limitations apply also to a number of physico-chemical methods (e.g., measurements of oxidation products, volatile compounds, drip loss, etc.). On the other side, spectroscopic assessment methods such as visible and infrared-based techniques, fluorescence, Raman, and NMR spectroscopy have shown the potential to overcome challenges related to traditional assessment methods [31; 33; 34]. In addition, recent progress and advances in the spectroscopic field has led to the development of hyperspectral imaging, enabling both spectral and spatial information from the scanned samples [35; 36; 37].