# Flavoromics Analysis of Passion Fruit-Roasted Chicken
## 2 Results and Discussion
### Evolution Patterns of Various Volatile Flavor Compounds  
The types and proportions of flavor components indicated that alcohols, esters, and hydrocarbons were the main volatile flavor components in all stages of processing (Table S2). With the extension of roasting time, aldehydes generated by the transformation of various compounds become the main flavor components. At the end of the roasting stage, various compounds gradually evaporated at a high temperature of 200 \({}^{\circ}\)C, and ultimately, hydrocarbon substances were the main volatile compounds in passion fruit-roasted chicken. The changes in aldehyde substances during the processing of passion fruit-roasted chicken are shown in Figure 1a. During the entire roasting process, a total of 16 aldehydes were identified, which first increased and then decreased during processing and reached their maximum values after 30 min of roasting. In raw chicken, the flavor of aldehydes accounts for the highest proportion at 60.55%, which is the compound with the highest proportion in raw meat, mainly derived from hexanal. The aldehydes that could be detected throughout the entire process from raw chicken to cooked products were glutaraldehyde, hexanal, and nonanal. When heating began, the identified aldehydeswere isovaleraldehyde, 3-furfurral, and phenylacetaldehyde. As the roasting process progressed, the content of aldehydes significantly increased (\(p<0.05\)), with a total amount of 638.82 ng/g at 30 min. There were still many retained aldehydes in the finished roasted chicken, including 3-furral and benzaldehyde, with values of 83.65 ng/g and 127.57 ng/g, respectively. Within 30-45 min of roasting, a small amount of heptanal is generated, which is believed to cause a fatty and rancid odor to meat products [26]. The changes in ketone substances during the processing of passion fruit-roasted chicken are shown in Figure 1b. During the entire roasting process, a total of seven types of ketone compounds were detected, and by 45 min of roasting, there were four types of ketone compounds with the highest flavor proportion (29.50%). The main source was ethyl maltol, which was released into the meat in large quantities at high temperatures, producing a strong sweet caramel flavor. In raw chicken, no ketone substances were detected, and 5-methyl-2-hexanone was only detected after the high temperature of 200 \({}^{\circ}\)C.  
The changes in alcohol substances during the processing of passion fruit-roasted chicken are shown in Figure 1c. During the entire roasting process, a total of 16 types of alcohol substances were detected, similar to the changes in aldehydes, which first increased and then decreased, reaching a maximum content of 289.22 ng/g after 30 min of roasting. In raw chicken, only four types of alcohols were detected, namely pentanol, hexanol, 3-octanol, and heptanol. Pentanol mainly resulted from the degradation of lipid hydroperoxides, and hexanol was derived from linoleic acid [27]. In the cured chicken, 13 types of alcohol substances were detected, indicating that some volatile alcohol substances in the pickling  
Figure 1: Changes in volatile flavor compounds during the processing of passion fruit-roasted chicken: (**A**) aldehydes, (**B**) ketones, (**C**) alcohols, (**D**) esters, and (**E**) hydrocarbons. a–f: different letters indicate statistical significance (\(p<0.05\)) between different groups. materials and passion fruit powder were released during the pickling process. The content of the important flavor substance L-linalool was significantly higher in the early stage of roasting than in the pickling stage (\(p<0.05\)), reaching a maximum content of 29.44 ng/g at 30 min of roasting, and eventually decreasing to 16.24 ng/g. The alcohol that could be detected throughout the entire process was hexanol, which has a fruity and sweet aroma. The changes in ester substances during the processing of passion fruit-roasted chicken are shown in Figure 1d.