# Flavoromics Analysis of Passion Fruit-Roasted Chicken
## 2 Results and Discussion  
### Analysis of Volatile Flavor Components in Passion Fruit Roasted Chick  
Using o-dichlorobenzene as the internal standard, the content of flavor components in passion fruit-roasted chicken was quantified. The specific types, contents, thresholds, EOAV values, and odor characteristics are summarized in Table S1. According to functional group classification, the main flavor substances in passion fruit-roasted chicken were aldehydes, ketones, alcohols, esters, hydrocarbons, ethers, and furans, with 7 categories and 44 volatile flavor substances in total. The generation of aldehydes mainly comes from the degradation and oxidative decomposition of chicken fat at high temperatures [16]. Six aldehydes were identified in passion fruit-roasted chicken, and the highest content was benzaldehyde (127.57 ng/g), followed by 3-furfurtal (83.65 ng/g) and then n-hexanal (57.21 ng/g). The pyrolysis products of amino acids participate in the Maillard reaction and Strecker degradation, thereby releasing small molecules of aldehydes. Benzaldehyde was a crucial aroma component generated by Strecker degradation of amino acids combined with lipid oxidation [17; 18]. The open-chain form of sugars and the non-protonated form of amino groups have the highest reactivity in the Maillard reaction. When pH increases, it promotes carbonyl ammonia condensation. Therefore, it can be inferred that in the aroma system of passion fruit-roasted chicken, the source of hexanal is mainly the carbonyl ammonia reaction. Ketone substances can be generated by the re-oxidation of unsaturated fatty acids and the Maillard reaction [19]. Four types of ketone compounds were identified in passion fruit-roasted chicken, namely 5-methyl-2-hexanone (22.85 \(\pm\) 2.76 ng/g), 3-hydroxy-2-butanone (58.91 \(\pm\) 7.08 ng/g), 2-furanylacetone (14.13 \(\pm\) 1.03 ng/g), and ethyl maltot (641.19 \(\pm\) 38.50 ng/g). Among them, ethyl maltot is derived from the addition of pickles, which can effectively enhance food aroma. Seven types of alcohol substances were found, the representative substance of which is 2-methylbutanol (124.56 ng/g). Nine types of acids and esters were identified, among which the contents of ethyl butyrate and ethyl lactate are relatively high, with up to 149.22 ng/g and 137.36 ng/g, respectively. Ester compounds are generated by the reaction of alcohol intermediates from fat oxidation. The total flavor contribution rate of esters was 54.51%, among which ethyl butyrate had a contribution rate of up to 50.44%. This is the primary flavor substance of passion fruit-roasted chicken. Hydrocarbon compounds were the most diverse flavor compounds in passion fruit-roasted chicken. Among them, 15 types of hydrocarbon substances had the highest content, mainly including \(\beta\)-Caryophyllene (151.78 ng/g), toluene (50.63 ng/g), \(\gamma\)- Turpentene (46.17 ng/g), and limonene (31.50 ng/g). Furan compounds are important aromatic substances formed by the Maillard reaction of flavor precursors, which give meat products a rich meat aroma. The furan compound identified in passion fruit-roasted chicken was 2-pentylfuran, with a content of 5.67 ng/g, which is a common flavor substance in meat products. Its main source is aldehyde oxidation [20]. To further explore the main aroma-contributing components in passion fruit-roasted chicken, it was necessary to combine the content of various flavor components and their thresholds to make judgments. When EOAV > 1, it was determined as the main flavor component. According to Table S1, 16 flavor components had an EOAV value greater than 1, including 5 aldehydes, 1 ketone, 2 alcohols, 3 esters, 3 hydrocarbons, and 2 ethers. Nonanal had a low odor threshold value and was related to lipid oxidation with green and fatty description [21]. N-hexanal, L-linalool, and phenylethanol \(\beta\)-Caryophyllene contributed to the fragrance of flowers such as grass, pine, gardenia, and lily of the valley [22].