## 3 Results and Discussion
### Effect of Pulsed-Light Treatment on Spoilage Microorganisms and Campylobacter
#### 3.2.2 _Campylobacter_
Figure 6: Effect of PL over meat color L*a*b* parameters. In the raw broiler meat samples (Table 2), initially identified as the main components from a relative total proportion of volatile aldehydes (23.64% \(\pm\) 4.26%) were the: Hexadecanl (6.55% \(\pm\) 0.78%), Nonanal (6.47% \(\pm\) 1.69%), Benzaldehyde (2.54% \(\pm\) 0.31%), (E, E)- 2,4- Decadienal (1.45% \(\pm\) 0.19%), and Hexanal (1.06 \(\pm\) 1.74%). Other volatile aldehydes were identified in smaller proportions, such as Heptanal, Octadecanal, and Octanal (0.71%-0.65%). The poultry samples presented low amounts of aldehydes, as described by [48], since they are low-fat raw meat. This study's main aldehydes, presented on raw poultry samples, are expected to derive from MUFA and PUFA oxidation, hydrolysis of phospholipids (plasmalogens), and Strecker degradation [49; 50; 51]. Nonanal has a low odour threshold value and can be associated with lipid oxidation of oleate hydroperoxide primary products with green and fatty descriptions [50]. (E, E)-2,4-decadienal (C26) is considered to be the most important odorant for chicken flavour compared to hexanal due to its much lower odour threshold [47]. Pentanal, hexanal, and (E, E)-2,4-decadienal were primarily responsible for the WOF in meat, which caused a loss of meaty, chicken-like, and sweet odour notes and the formation of green, cardboard-like, and metallic off-odours [52]. Hexanal and 2,4-decadienal are the most abundant aldehydes identified in chicken flavour, known to be linoleic acid's primary oxidation products. Long-chain aldehydes as the hexadecanl and octadecanal might derive from the hydrolysis of phospholipids, particularly plasmalogens, in poultry meat [53; 54]. Plasmalogen contains a vinyl ether substituent with 16:0 or 18:0 alkyl groups at the sn-1 position of glycerol, which generates the corresponding aldehydes on hydrolysis. The presence of hexadecanl and octadecanl have been reported in raw or heated meat from several species, including poultry [49; 53; 54] and in the chicken breast meat [55]. Benzaldehyde was also detected in poultry meat samples, and it is a crucial aroma component existent in the breast and generated by the Strecker reaction of some amino acids, such as leucine and phenylalanine [52]. In general, and independently of the binomial conditions of this study, the treatments with PL can induce significant differences in poultry meat flavour. Indeed, compared to the control, a relative reduction of all aldehydes in PL-treated poultry samples was observed. It seems that PL could induce the loss of chicken-like, chicken skin-like, and sweet odor notes in fresh poultry meat with the significant reduction of hexadecanl, nonanal, benzaldehyde, (E, E)-2,4-decadienal (1.45% \(\pm\) 0.19%), and hexanal apart from all other aldehydes. The relative reduction of these aldehydes in total meat volatiles suggests that they might be sensitive to PL, resulting in the formation of other volatiles compounds. In fact, aldehydes and ketones were reported to be susceptible to photochemical reactions through Norrish-type reactions, resulting in the formation of other derivatives [56; 57]. Further studies will be needed to evaluate the photochemical products that might be generated from aldehydes in pulsed-light-treated meat under storage. Despite that, evident prooxidant action and the development of lipid oxidation with the application of PL were not expected because samples were from the breast with low-fat content, all samples were vacuum packaged, and the application of PL did not increase sample temperature relevantly. Moreover, the high total antioxidant capacity (TAC) and very low Mb content in chicken breast described by [PERSON] et al. [58] might have a protective effect due to a diet supplemented with vitamin E [48].