Study Of Age-related Duck Main Flavor

Age is one of the most important factors that can crucially influence the flavor of duck. Thecompositions of duck meat changes with age and the some metabolites, especially for amino acids,nucleotides as well as fatty acids of muscle will make different flavor in rearing period. The presentstudy investigated any age-associated flavor differences and the flavor precursors substances. It notonly described the mechanism of flavor formation but also provided theoretical basis in developingthe produces of duck meat. In odor to analyze the metabolite, we combined the traditionaltechniques including GC、HPLC、GC-MS and new technique NMR. The results were as follows:1. Analysis of volatile flavor compounds in duck meat of different ages.Cherry Valley ducks were studied in this paper. Headspace solid phase microextractioncombined with gas chromatography-mass spectrometry was used for the analysis of the volatileflavor compounds in ducks aged27days、50days、170days、500days. Analysis of flavorcompound showed that there were total37compounds in duck meat. The number of the kinds ofvolatile flavor compounds was similar but the content differed. The total amounts of aromatichydrocarbons，ketones and esters increased with age. Among the main flavor compounds whichmay cause the difference flavor of duck meat, hexanal and2,3-octanedione increased significantlywhile there is a significant decrease in amounts of nonanal and octoaldehyde,2-pentyl-furanincreased too.2. The effect of age on composition and content of basic nutrition compounds contentand main flavor precursors influencedThe muscle of leg was taken to study the basic nutrition compounds and the results showedthat the content of water decreased with age significantly, but the content of crude fat increased andthe content of crude protein reached highest in duck aged50days.There was no significant difference on kinds but relative contents of fatty acids of differentages. The content of saturated fatty acid decreased and the content of monounsaturated fatty acidincreased with age. The relative content of polyunsaturated fatty acids in duck of27d wasobviously higher than others. Fatty acids differed visibly from duck of27d to170d. However, therewas no significant difference between duck of170d and500d. The main fatty acids such asPalmitic acid, stearic acid, Palmitoleic acid, Oleic acid, linoleic acid and Arachidonic acid changedinsignificantly, which would cause the changes of the content of fatty acids. The content of free amino acids in duck meat is colsely related to age. The total amount ofamino acid increased with age. Although the level of main amino acid such as alanine, glycine,proline and glutamine, valine decreased with age significantly, asparagine, arginine, tyrosine,tryptophan, threonine, isoleucine increased.The level of sugar increased with age befor170d but decreased in500d. There was asignificant difference between individuals.3. Optimisation of duck extraction methods with NMR methodMetabolomics are studied by using nuclear magnetic resonance (NMR) technology as a newbiological research methods is on the rise. For better application of nuclear magnetic resonance(NMR) technology and rapid, convenient detection in the analysis of duck meat, extract methodwas optimized. We compared three cell disruption methods including freeze-thaw cycles, milling,ultrasonic treatment and two extraction solvents including phosphate buffer solution and methanolsolution to test whether such extraction was efficient or not. The results showed that there were nosignificant metabolite-composition differences between extracts obtained from these theredescription methods and the milling extraction as the method of choice since it is efficient, simpleto use and capable of high throughput studies. Compared with phosphate buffer extracts, theaqueous methanol extracts contained higher levels of lactate、alamine、creatine、cysteate、inosine、histidinal、5’-IMP, but lower levels of isoleucine. Aqueous methanol was more efficientfor extracting hydrophilic antioxiddants, which appeared to be the factor resulting in the qualitativeand quantitative differences.4. NMR-Based metabolic study of age profiling in duck meatResonances were assigned to specific metabolites based on literature data and publicdatabases with further confirmation by2D NMR spectra. The duck extracts are dominated by28metabolites including5carboxylic acids,2nucleic acids,9amino acids and2sugars.The effect of age on the chemical components was observed and comprehensive multivariatedate analysis showed significant separation between extracts of duck form four ages. Althoughlactate, dimethylamine, creatine, cysteate increase with age, acetate, acetone, trimethylamine,beatine, fumarate, inosine, and chain amino acids decreased.