# Applications of Pulsed Light Decontamination Technology in Food Processing: An Overview
## 6 Effect on Food Quality Characteristics
### Effects on Nutrients and Bio-Active Components  
As already emphasized, PL processing tends to interact with the superficial layers of the food products which are in the vicinity of the light source. So, it does not appear to hamper their inner layers; hence, nutrients and bio-active components present within the inner layers remain intact as untreated samples. Researches have been done in plenty to study the effect on PL processing on food nutrients and bioactive components. On carrying out a nutritional evaluation of PL-treated frankfurters, [PERSON] et al. [6] observed no differences in proteins, vitamins like riboflavin and vitamin C, nitrosamine, or benzopyrene content compared to untreated samples, while a strong loss of riboflavin was reported in foods due to heat, light, and oxygen. Contrastingly, riboflavin content in products like chicken, beef and fish were did not decrease using pulsed UV treatment [135]. However, riboflavin and vitamin E contents were reduced only to 95% by four light pulses and to 85% by eight light pulsesof their initial value, respectively. [PERSON] and [PERSON] [133] demonstrated pronounced oxidation in the treated ham samples in terms of the oxidative stability index (OSI) in hours, which showed a decreasing trend as storage period progressed. [PERSON] et al. [15] reported that the PL treatment of mushroom reduced some phenolic compounds and vitamin C content. Lipid oxidation is induced in many food products post-PL processing and remains a challenge [102; 105; 123; 133]. [PERSON] et al. [123] observed PL induced lipid oxidation on chicken surfaces. The intensity of lipid oxidation in control and treated chicken samples showed a difference of 0.16 mg malondialdehydedehyde (MDA)/kg of chicken meat. [PERSON] et al. [102], in their PL treatment study of cheese at 5 cm distance for 40 s, found that levels of lipid peroxidation as MDA concentration was found to be about 30.7 and 34.8 \(\upmu\)g MDA/g cheese in packaged condition and unpackaged conditions respectively, with unpackaged cheese undergoing higher oxidation due to exposure to oxygen. MDA levels in PL treated salmon and pork increased by 39.3% and 25.5%, respectively after PL processing [105]. After PL treatment of milk, [PERSON] et al. [136] did not notice any lipid oxidation and changes in amino acid sequence and composition of proteins. [PERSON] et al. [110] however talked about the possibility PL induced photochemical changes in milk lipids, proteins and oxidation of vitamins. [PERSON] et al. [137] studied the protein oxidation of cheese as affected by PL, taking bovine serum albumin (BSA) as a model protein. They measured oxidation in terms of carbonyl content increase (nmol carbonyls/mg BSA), obtaining an increase in carbonyls above 10 nmol/mg BSA for fluence of 11.4 J/cm\({}^{2}\). Thus, lipid oxidation tends to remain a bottleneck in PL processing of fat rich products  
Fruits like grapes and berries represent a rich source of phytonutrients and polyphenolic compounds. The retention of these compounds is necessary from the nutritional point of view. Impact of PL processing on these compounds has been a topic of continuous research. There was a decrease in total phenol and antioxidant activity (in Trolox equivalents) and impact on sensory attributes in 8 s (fluence of 1.17 J/cm\({}^{2}\) per pulse) PL treatment of apple juice [66]. However, light-based technologies, like continuous UV-C processing, have been shown to increase the concentration of phytochemicals in fruits. This could be due to the activation of plant defense response to severe treatments, which express the formation of the phytochemicals like phenolic compounds. In a study, level of resveratrol in grapes increased by more than 10-fold [138]. Given the similarities with UV, PL is claimed to have the similar effect of increasing phytochemicals [41]. Nevertheless, a study by [PERSON] et al. [92] showed no effect on the antioxidant capacity at fluence level of 5.1 J/cm\({}^{2}\) and assisted thermosonication for orange juice.