## 3 Non-Thermal Technologies in Food Processing
### UV Radiation
#### 3.2.1 Application in Fruits and Vegetables  
UV light has been widely explored for the decontamination of fresh fruits and vegetables. In particular, also UV-assisted TiO\({}_{2}\) photocatalysis (TUV) [115] has been recently investigated for disinfection from _E. coli_ on oranges' surface and juice [116]. _L. monocytogenes, Staphylococcus aureus, E. coli_ O157:H7, _Salmonella typhimurium_, and _Saccharomyces cerevisiae_ have been inactivated in commercial apple juice after treatment with TUV followed by a high hydrostatic pressure process [117]. In addition, [PERSON] et al. have investigated UV-C light irradiation on apple juice in order to lower the population of _E. coli_, which was reduced after the experiments by (3.2 \(\pm\) 0.4) and (3.8 \(\pm\) 0.2) log\({}_{10}\) colony-forming units CFU/mL [118].  
On the other hand, UV light reduces considerably the vitamin C content in apple juice. [PERSON] at al. have analyzed the modifications made on juice by continuous monochromatic low-pressure (LPM) and medium-pressure polychromatic (MPM) mercury UV lamps. Vitamin C reduced by \(-\)1.30 \(\pm\) 0.07% with an LPM UV lamp after about 140 min and by \(-\)5.45 \(\pm\) 0. 27% with an MPM UV lamp after almost 5 min. The pH, of value 3.56 \(\pm\) 0.01, was not affected [119].  
Low-pressure (LP) UV light combined with mild temperatures on freshly squeezed orange juice inactivate part of _E. coli_; the treatment reduces of 16.45% ascorbic acid content and 63.96% the pectinethylesterase activity but it does not affect acidity, pH and color [120]. Furthermore, _E. coli_ and _S. typhimurium_ has been inoculated in coconut milk to evaluate UV-C light effects on these bacteria and the consequences on the milk physico-chemical, bioactive, microbial and sensory characteristics. UV-C light does not influence pH, acidity and soluble solids; otherwise phenolic compounds are reduced by 26.6%. Regarding bacteria, these are reduced by (4.1 \(\pm\) 0.1) log\({}_{10}\) CFU/mL after 30 min of UV-C treatment [121]. [PERSON] et al. have investigated the effectiveness of ultraviolet-C radiation (254 nm) as a substitute process to the SO\({}_{2}\) addition to deactivate microorganisms in grape juices and wine. It has been experimented a log\({}_{10}\) CFU/mL bacterial drop of 4.97 and 4.89 in Chardonnay and Pinotage, respectively. In Chenin blanc and Shiraz juice, a log\({}_{10}\) CFU/mL decrease of 4.48 and 4.25, respectively [122]. Black pepperons have been analyzed under UV light emitting diode (UV LED) irradiation. After treatments with 280 nm wavelengths and durations of 20 min, bacillus subtilis concentration decreases to (6.20 \(\pm\) 0.44) log\({}_{10}\) CFU/g [123]. _L. monocytogenes, E. coli, Bacillus subtilis_ and _S. typhimurium_, after inoculation in onion powder, garlic powder, cheese and onion powder and chilli powder, have been treated with UVC-LEDs light at wavelengths of 270 nm. A substantial reduction of 0.75 up to 3 log\({}_{10}\) CFU/g has been obtained after 40 s of UVC-LED exposure times [124].  
UV-light has been studied not only as disinfect method. In their work, [PERSON] et al. analyze if UVA light and UVC light pre-treatment (1 kJ/m\({}^{2}\)) can enhance the concentration of bioactive compounds such as carotenoids, polyphenols and hydrophilic-lipophilic antioxidant capacity in tomatoes during the post-harvest step. Unfortunately, UV irradiation alone does not considerably influences the carotenoid content, neither phenols or polyphenols concentration [125].