Studies On Aroma Compounds Of Chinese "Kouzijiao" And "Jiannanchun" Liquors

The volatile trace compounds in Chinese liquors were considered the major components of the particular aroma of Chinese liquors. In this paper, the volatile aroma compounds of Chinese"Kouzijiao"and"Jiannanchun"liquors were analyzed by gas chromatography–olfactometry (GC–O), and compared with the main aroma compounds of"Jiannanchun"liquor, the main aroma compounds of"Kouzijiao"liquor were determined preliminarily; Study on changes in the concentrations of the main aroma compounds during the maturation of Chinese liquors; Aroma compounds in Daqu were investigated with Aroma extract dilution analysis (AEDA), then quantified by headspace solid phase microextraction (HS–SPME) followed by gas chromatography–mass spectrometry (GC–MS). The main contents are as follows:Aroma compounds in Chinese"Kouzijiao"and"Jiannanchun"liquors were extracted by liquid-liquid extraction (LLE) and then analyzed by GC–O and GC–MS. A total of 104 aroma compounds were identified in"Jiannanchun"liquor, the main aroma compounds were ethyl hexanoate, 1,1-diethoxy-3-methylbutane, ethyl butanoate, ethyl pentanoate, hexanoic acid, 3-methylbutanol, ethyl 3-methylbutanoate, ethyl 2-methylpropanoate, butyl hexanoate and butanoic acid (Osme≥3.00). A total of 113 aroma compounds were identified in"Kouzijiao"liquor, the aroma intensities of fatty acids and alcohols were quite with the"Jiannanchun"liquor. Esters are important aroma compounds of"Kouzijiao"liquor, but the whole aroma intensities were weaker than"Jiannanchun"liquor. Vanillin and 4-vinylguaiacol were the important aroma compounds because of strong aroma intensities. On the basis of Osme values, the most important compounds in"Kouzijiao"liquor were ethyl hexanoate, 4-vinylguaiacol, hexanoic acid, 3-methylbutanol, ethyl 3-methylbutanoate, 4-ethylguaiacol, vanillin, 2-phenylethyl acetate and butanoic acid (Osme≥3.00).Total of 68 aroma compounds were quantitative analysed by direct immersion–solid phase microextraction (DI–SPME). On basis of concentrations and odor active values (OAV) of the aroma compounds, hexanoic acid, butanoic acid, 3-methylbutanoic acid, phenylacetaldehyde, ethyl phenylacetate, 4-ethylguaiacol, 4-methylphenol, nonanal, dimethyl trisulfide, ethyl hexanoate, ethyl butanoate, ethyl pentanoate, ethyl heptanoate, and some ethyl esters have high OAV values relatively.Changes in the concentrations of aroma compounds during the maturation of liquors were studied, and in orde to know the quality change rules. The results showed that the total concentrations of aroma compounds in"Kouzijiao"liquors were increased first, then decreased during the maturation. The esters, aromatic compounds, phenols with strong aroma intensities were also increased fist, were then decreased during the maturation. So, the aroma compounds were formed during the beginning of storage. However, the total concentrations of aroma compounds were decreased always in"Jiannanchun"liquors, and the decrement of total esters and the increment of total acids were occurred during the maturation. The hydrolyzed effect was the main cause of the decrement of important esters.Aroma compounds in high temperature kouzijiao Daqu and moderate temperature jiannanchun Daqu were identified by AEDA. On the basis of flavor dilution (FD) value, the important aroma compounds in high temperature Daqu were vanillin, ethyl hexanoate, 4-vinylguaiacol, phenylacetaldehyde, butanoic acid, hexanoic acid, and 2,6-dimethylpyrazine (FD≥64). The important compounds in moderate temperature Daqu were ethyl hexanoate, phenylacetaldehyde, hexanoic acid, benzaldehyde, phenylethanol, and ethyl phenylacetate (FD≥64).The aroma compounds in 5 different Daqus were studied by HS–SPME coupled with GC–MS. The effects of sample concentration, dissolved time, ultrasonic extraction time, and different extracting solvent on the extraction of aroma compounds were also investigated. The best extraction conditions were as follows: 5 g Daqu powder, 1%Cacl, was dissolved in 10 ml deionized water for 1 hour, then it was extracted by ultrasonic for 30 min, and obtained liquid sample with centrifugal effect, finally the sample was detected by HS–SPME. Total of 52 aroma compounds were detected by GC–MS, including 7 acids, 12 alcohols, 2 esters, 3 phenols, 7 aldehydes and ketones, 9 aromatic compounds, 3 furans, 5 pyrazines, 1 sulfide compound, 1 lactone, and 2 other heterocyclic compounds.