# Flavor Differences of Edible Parts of Grass Carp between Jingpo Lake and Commercial Market
## 3 Results and Discussion
### Volatile Compounds
Esters are another class of organic compounds with unique odors, usually formed by the reaction of carboxylic acids and alcohols and responsible for the formation of the characteristic aroma of aquatic products, which can mask rancid odors but also provide positive floral and fruity aromas to products [36]. Of the 53 esters detected in our study, methyl esters were the main compounds. Nineteen methyl esters were successfully identified, including methyl1 myristoleate, methyl 2-hydroxystearate, dimethyl dl-malate, methyl acetylglycinate, hexacosanoic acid, methyl ester, methyl benzoate, (2-bromomethyl-[1,3]dioxolan-2-yl)-acetic acid, methyl ester, butanoic acid, 4-ethoxy-, methyl ester, (\(E\))-3,7,11-trimethyldodec-2-enoic acid, methyl ester, heptadecanoic acid, 9-methyl-, methyl ester, pentanoic acid, 2-hydroxy-3-methyl-, methyl ester, carbamodithioic acid, diethyl-, methyl ester, trimethylene borate,methyl octa-O-methyllaminaribionate, methyl-(aminosulfanyl) formate, tetraethylmecgly-col monomethyl ether, methyl 3-hydroxytetradecanoate, methyl 5-methoxy-3-oxovalerate, 7-hexadecenoic acid, (\(Z\))-methyl ester. Methyl esters impart fruity odors to meat products [37]. Methyl benzoate was the most abundant methyl ester in the grass carp samples in our study. The contents of methyl benzoate in JT, CT, and JB were higher than those in JA and CB (\(p<0.05\)), although there were no significant differences between JB and CB (\(p>0.05\)). Methyl benzoate provides prune, lettuce, herb, and sweet notes. Isopropyl palmitate (fatty odor) was detected exclusively in JA and JB. Ethyl 2-methylbutyrate, characterized as having an apple or apple-like aroma, was detected in JB. It contributes positively to the flavor of JPGC. Although 15 hydrocarbons were identified, they had little effect on the overall flavor of grass carp because of their high odor threshold values [38]. CT had the highest total hydrocarbon level, followed by JT, which was consistent with the measurement results of the E-nose W1S sensor. The hydrocarbon most detected in the grass carp samples was henicosane. The henicosane contents in JT and CT were higher than those in JA, JB, CA, and CB (\(p<0.05\)). Among the eight ethers identified, six were found in JB, which had the highest total ether content and included estragole, anethole, 2-(2-methoxyethoxy)ethanol, 2-[2-(hexyloxy)ethoxy]-ethanol, tetraethylene glycol diethyl ether, ethanol, and 2-(2-ethoxy)-The most abundant was estragole, characterized by an anise-like aroma, which contributed to the flavor of JPGC. Anethole was detected in all sample groups but was significantly highest in JT. It has a unique fennel smell and corresponding sweetness and can be used in all foods, especially pastry foods. A pleasant fragrance positively influences the flavor of grass carp. Aside from the above compounds, some flavor compounds, such as 3-phenylindole, 1,2-bis(trimethylsilyl)benzene, butylated hydroxytoluene, azalene, and naphthalene, are challenging to classify. Naphthalene was detected in CB and CT. The substance has a strong tar odor and adversely affects the odor of CGC. These unpleasant odors may come from water or environmental pollution.