## 6 Discussion  
Traditional food preservation methods can reduce the number of pathogenic microorganisms to safe levels. However, these methods lead to the loss of organoleptic characteristics such as heat-sensitive vitamins, aromatic compounds, and color pigments. Recently, non-thermal technologies have attracted increased attention [203]. High hydrostatic pressure, cold plasma, UV light, pulsed electric field, and ultrasound (US) can effectively destroy microorganisms with almost zero adverse effects on the nutritional value and sensory properties of food materials. These methods apply mild temperature conditions and shorter processing times, which retain the flavor, enhance the shelf life, and inactivate enzymes [18; 19; 22]. This makes them attractive for producing high-quality and fresh products. Ultrasound offers many advantages such as a decrease in the use of fossil fuels to provide energy during food processing, including drying and heating; decreases in the amount of water consumed; enhancement of productivity, and retaining the nutrients of the product [18; 46]. Ultrasound waves (frequency >20 kHz) with specific intensity and amplitude are used for inactivation of microorganisms in foods. The cavitation phenomenon is responsible for microbial destruction [46], since cavitation bubbles are formed through cycles of pressure created by high-intensity ultrasound. The bubbles grow over several compression/rarefaction cycles, reaching an unstable size, and then they collapse, leading to the release of energy. Very high shear forces are induced, creating high-temperature and pressure conditions (5000 K and 5000 atm) and leading to the structural destruction of many microorganisms [33; 48]. Furthermore, their benefits go beyond the inactivation ofmicroorganisms: enhancement of compounds [85], meat tenderization [98], mass transfer acceleration [95], improved emulsification and homogenization [109], and so on. UV, as a physical preservation technology, is surely a fast and handy way to reduce or eliminate pathogens; in particular, it has been revealed as a promising alternative to traditional thermal treatment for liquid foods, post-processing treatment for cheese and meat, and shelf-life extension of fresh products [114], while still maintaining low energy demands. On the other side, UV radiation is less effective with turbid liquids with particulates, due to strong light absorption, scattering, or reflection effects. In addition, it is necessary to be careful about some compounds that can be damaged by the radiation [119; 128; 129], generating a reaction that can ruin the flavor and the food itself [88]. Similarly, also, ultrasounds occasionally can provoke color [71], antioxidants [72] and polysaccharides modifications [73], degradation of fats, radicals formation and oxidation [74] in high content lipid foods, due to the strong effects of cavitation phenomena. Ozone is a potent oxidant and disinfecting agent that does not require thermal energy, so this technology should be considered suitable for heat-sensitive foods [160]. The bactericidal effect of ozone has been proved on a wide variety of organisms, including Gram-positive and Gram-negative bacteria, vegetative cells, and spores. The exposure to fruits and vegetables with ozone increases the shelf life of the products, and it leaves no residues, since it decomposes quickly [246]. However, this treatment is not advised for meat decontamination since it oxidized myoglobin and oxymyoglobin to methyloglobin, leading to meat discoloration [159]. High hydrostatic pressure processing has potential in the development of health foods and at the same time can enhance or retain the nutritional value of raw material and food products. The color, taste, quality, and nutritional content of food are not affected by HPP technology and remain at their original prices [247].