Studies On Characteristic Aroma Compounds In Fen-liquor

Fen-liquor is used the ground jar as the fermentation tank. It is a brewing liquor which daqu made of pea and barley as saccharifying ferment, sorghum as raw materials, millet shell as auxiliary material,"Two cleaning of steamed clean-burning"as fermentation technology. And it is the most typical representative of Light aroma style liquor. Fen-liquor has a glorious past and the many advantages. But its market share was gradually decreasing in recent years. There had not been improvement for a long time. The major reason for this was that the technology of Fen-liquor lacked major breakthroughs. For the research of most important trace elements-aroma compounds which playd a key role in Fen-liquor, few of them had been detected. And test results and evaluation results failed to integrate. The aroma of liquor is a product attribute which is is very important for the liquor. Therefore, it is necessary for us to comprehensive, the aroma compounds of Fen-liquor. It is an urgent need for Fen-liquor to solve the problem of finding, quantifying and the characteristics of aroma compounds. Mean while determining their ratios was a breakthrough in the foundation. The main purpose of this paper was to establish an effective method on the existing basis, which can be used to systematic and in-depth study aroma compounds of the Fen-liquor, and it focused on the characteristics of aroma compounds. At the same time Laobaigan and the Xifeng-liquors were selected as a reference. The researchs were as follows:Qualitative analysis of aroma compounds in Fen, Laobaigan and Xifeng-liquors by gas chromatography–olfactometry (GC–O). Total of 135 aroma compounds were detected, in which 115 aroma compounds were identified. Among them, 99 aroma compounds were identified in Fen-liquor, 106 aroma compounds in Laobaigan-liquor, 102 aroma compounds in Xifeng-liquor. A total of 85 kinds of common aroma compounds were in Fen and Laobaigan-liquors. 75 kinds were in Fen and Xifeng-liquors. Among them, 71 kinds were in Fen, Laobaigan, Xifeng-liquors. Most of them were esters, aromatic and phenolic compounds, fatty acids and alcohols. Comparison of them, we can found that the kinds of fatty acids were almost same in three types of liquor. From the result, we counld conjectured that the fatty acids aroma compounds were very small contributions to the characteristic of aroma compounds in Fen-liquor. Compared the aroma contributions, the first were aromatic and phenolic compounds were the first, esters were the second, and fatty acids were the third, while alcohols were also important.It was a relatively simple, rapid, and accurate method for the quantification of aroma compounds in Fen, Laobaigan and Xifeng-liquors by using DI–SPME followed by GC–MS. The result was ideal that quantification of organic acids in liquor by using HPLC. Under the conditions described above, the method linearity was satisfactory, with correlation coefficients higher than 0.99 in all cases. As the same time, the linear range of standard curve contained the concentration of aroma compounds in liquors. Most of the recoveries of analyzed compounds varied between 80% and 120%. The relative standard deviations were all below 15%. The similar results were found in samples. The results showed that the method had good accuracy which can be satisfied with analytical requirement of the trace elements in liquor. Total of 79 aroma compounds were quantitative analyzed by direct immersion solid phase micro-extraction followed by gas chromatography-mass spectrum (DI–SPME–GC–MS) and high performance liquid chromatography (HPLC). Through quantitative results, we knew that the amount of ester compounds was most in all of the aroma compounds among Fen, Laobaigan, Xifeng-liquors. And the proportion of aromatic and phenolic compounds in Fen-liquor (1.68%) was the largest. The content of 3-methyl butanol, 2-methyl propanol, ethyl acetate, ethyl lactate and acetic acid was much larger than other aroma compounds in the three kinds of liquors. In trace compounds,β-phenylethanol, furfural andγ-nonlactone had relatively high levels in Fen-liquor. According to quantitative results, odor active values (OAVs) of these quantitative analyzed aroma compounds were calculated. Compared with these OAVs, we can see that the number of ester aroma compounds was most among the aromas which the concentrations were greater than their threshold values in liquors. Aromatic and phenolic compounds were followed. Alcohols compounds were third. These aroma compounds presented fruity, floral, sweet and alcoholic which were similar with aroma stype of Fen-liquor. And they were the important aromas of it.Total of 54 aroma compounds were quantitative analyzed by DI–SPME–GC–MS and HPLC in the seven kinds of different storage-time original Fen-liquors. The amount of the aroma compounds showed downward trend in Fen-liquor with the extension of storage time. Because of the hydrolysis and volatilization, the amounts of esters declined significantly in liquors. While the organic acids and alcohols increased slightly with the extension of storage time. The percentage of aromatic and phenolic compounds content with total amount increased 8.68 times, which showed obviously increase tendency. It maybe played a very important role in storage and aging of Fen-liquor. OAV values of esters were the largest, and ethyl octanoate was the largest in all of fen-liquors which had the different storage-time. And the number of aroma compounds which OAV value was greater than 1.00 was most. Aromatic and phenols compounds were followed. These two types of substances were prominent in Fen-liquor.Through dilution analysis of the extraction of aroma components of Fen-liquor, we could know the phenolic and aromatic compounds had the largest flavor dilution (FD) values. They were the most important aroma compounds in Fen-liquor. Comprehensive analysis of qualitative, quantitative, and the things during storage-time of aromas in Fen-liquors, it showed that phenylacetaldehyde, 4-ethyl guaiacol, ethyl benzeneacetate, 2-phenylethyl acetate,β-phenyl ethanol, ethyl octanoate, ethyl acetate, 3-methyl butanol, 2-methyl propanol and 1-octanol made great contributions. They were the characteristic aroma compounds of Fen-liquor.