Research And Application Of The Relationship Between Liquor Composition And Its Quality

As a special and traditional product, Chinese liquor plays an important role in the life of Chinese and social etiquette. It has gained excellent reputation in the world due to its unique technology, style and quality. Thus Chinese liquor shares a bright prospect with other famous distillates in the world market. However, empirical guidance is required and uncertainty exits with traditional technique. Therefore, it is significant to explore the factors which can affect liquor quality, summarize and improve traditional liquor manufacturing technology. It will graft the modern system to ensure stable precious hand-crafted quality created by traditional method. It can also promote the healthy development of liquor industry.In the present study, factors affecting liquor quality were systematically studied with Fenjiu, one of the most popular light aroma style beverages. GC/MS, chromatography, spectrum and electrochemistry were applied during the experiment. The contents and results are following:1. This study investigated the changes in aroma compounds, electrical conductivity and metal content of Fenjiu under different ages (from 0 to 30 years) systematically. Results showed that the conventional aging behavior of Fenjiu was due to the synergistic effects of volatilization of low boiling point matters, oxidation of dissolved oxygen, balance between esterification and hydrolysis, weak interactions between molecules and involvement of metal elements extracted from storage vessels. Based on this understanding, by simulating the natural storage environment and condition, a liquor aging equipment named multistage-spraying high gravity rotating packed bed (HGRPB) was developed locally and successfully applied to artificial liquor aging in industry for the first time. Comparisons of aroma compounds, electrical conductivity, metal content and sensory evaluation were made to identify the differences between the treated and untreated liquors. It was found that the liquor treated by this equipment at the speed of 2-3 t/h obtained qualities equivalent to the liquors conventionally aged for 2 years by a cluster analysis. The present study establishes a new way for liquor aging utilizing of HGRPB technique.2. The change rule of pH, electrical conductivities and the contents of flavor components with liquor age were systematically analyzed. Based on this, with the help of multiple linear regression (MLR) and partial least square regression (PLSR), a model of liquor property and its age was established. The estimation stability and generalization ability of the models were strictly analyzed by both internal and external validation. The correlation coefficient R of established models, leave-one-out (LOO) cross-validation (CV), Qext of MLR were 0.9990,0.9980,0.9984; the result of PLSR was the following:R and RLOO were 0.9949,0.9840. The results showed that the model have great robustness and good predictive abilities. The method plays an important role in identifying the Fen-flavor liquor age in the theoretical and application.3. The relationship between the qualitative stability of low-alcohol liquor and the addition water was studied by determining the electrical conductivities and dielectric constants of the tap, softened and purified water and the low-alcohol liquors blended with them, respectively. In this way, the change rules of main aroma compounds in the blended low-alcohol liquors during storage, the composition and the major factors which influence the qualitative stability of the colloidal solution were explored. Results showed that proper contents of metal ions in the addition water could increase the stability of liquor colloidal solution, decrease the dielectric constant of the liquor system, restrain the hydrolysis of the esters and consequently increase the stability of low-alcohol liquor. Accordingly, a new method of improving the stability of low-alcohol liquor was established by adding corresponding carboxylates in the addition water. In contrast to the control sample, the total contents of ethyl acetate and ethyl lactate in 38° mild aromatic Chinese spirits were increased by 31.0%, the total contents of ethyl caproate, ethyl acetate and ethyl lactate in 38° strong aromatic Chinese spirits were increased by 10.2% one year later.4. A reliable method for determining the organic acids in Chinese liquors by derivatization GC-MS is reported. Acetic acid, butyric acid, isovaleric acid, pentanoic acid, caproic acid, heptylic acid and lactic acid were quantified in this text. The SIM mode was employed in the analysis and presented high accuracy, reproducibility, and reduced the matrix effect effectively. The calibration curves were obtained with a satisfactory correlation coefficient of 0.9929 to 0.9994. The precision results showed that the relative standard deviations (RSD) of the repeatability were <3.01%. The accuracy of the method was confirmed with an average recovery ranging between 82.43% and 109.38%. The proposed method was used for the determination of organic acids in different kinds of Chinese liquor, and satisfactory results were obtained.5. The chemical structures of 16 phthalic acid esters (PAEs) have been studied by molecular electronegativity distance vector (MEDV) descriptors. The linear relationships between gas chromatographic-mass spectra time and the MEDV have been established by a multiple linear regression (MLR) model. The estimation stability and generalization ability of the model were strictly analyzed by both internal and external validation. The correlation coefficient (R) of the established model, leave-one-out (LOO) and Qext of MLR were 0.9110,0.8556 and 0.8914, respectively. The result shows that the MEDV can be characteristic the structure information of PAEs, and the QSRR model have great robustness and good predictive abilities. The proposed method provides a useful way for identification of PAEs by gas chromatography in liquor plastic packaging material.