| Guangdong Hakka rice wine has a long history, which lasted5,000years. It is fermented by glutinous rice and red kojic rice and it is rich in carbohydrates, amino acids, vitamins and organic acides, etc. Its carbohydrates are basically produced during fermentation including glucose, fructose and other monosaccharides and maltose, isomaltose, isomaltotriose, panose and other oligosaccharides. They are important compenent of the flavor of Hakka rice liquor which bring to the wine sweet and mellow sense, have a great contribution to the nutritional value and also have a certain impact on the quality characteristics of the color, stability. This thesis discussed the detection method, dynamic changes, factors of the carbohydrates in Hakka rice wine and their quantitative relationship with qualityFist of all, a method was developed to determine five sugars including glucose, isomaltose, isomaltotriose, panose, and maltose in Hakka rice wine by reversed phase high-performance liquid chromatography after pre-column drerivated with1-phenyl-3-methyl-5-pyrazolone (PMP). The optimum derivation conditions and chromatographic conditions were discussed. The result indicated that the optimum derivation conditions were as follow:the reaction temperature was70℃, the reaction time was30min, the molar ratio of PMP to glucose was10:1, the molar ratio of NaOH to glucose was3:1. The derivation product was extracted by trichloromethane for three times and then injected to analysis. The chromatographic conditions were as follows:the detection wavelength was at245nm, the molar ratio of acetonitrile to ammonium acetate buffer (0.1mol/L) was22:78at a flow rate of1mL/min, the pH of ammonium acetate buffer was5.5. A well separation of five sugars was got. The recovery rates were in93.13%～102.08%with the relative standard deviation (RSD) of0.96%to2.48%.Secondly, the content of carbohydrates in21Hakka mother wine samples including different manufacturers in the same origin, different aging time of the same origin, and different origin were determined and theirs’ significance were analyzed. The content of carbohydrates in the wine samPles from different manufacturers in the same origin showed a significant difference (p<0.05). In the wine samples of different aging time, the content of glucose decreased substantially with aging time increasing. The distintion between Hakka rice wine and Shaoxing rice wine was that the former one had tens of times higer glucose and several times less oligosaccharides than the latter’s.Thirdly, the dynamic change of the carbohydrates during fermentation process in Hakka rice wine was monitored. The factors on carbohydrates metabolism and their content were studied by the correlation analysis. The results showed that:the dynamic trend of glucose, maltose, and isomaltose were basically consistent during the fermentation process. At the primary stage of fermentation, their content showed a rising trend and then a trend of gradual decline along with the fermention and reached the lowest point on the seventh day. At the final post stage of fermentation, the three got a rising trend. The content of panose couldn’t be detected at20th day. The correlation results showed fermentation condition had a great impact on the content of five sugars. There was significantly positive correlation (p<0.01) between the content of isomaltose and four fermentation parameters. The content of isomaltotriose had a significant negative correlation (p<0.01) with dosage of red yeast and a significant positive correlation (p<0.01) with the other three parameters. There existed a significant negative correlation (p<0.01) between maltose and the four; there was a significant negative correlation (p<0.01) among the content of glucose, dosage of wheat and main fermentation time.Finally, quantitative relation of content of carbohydrates and three quality characteristics of Hakka rice wine were analysed by correlation analysis and multiple regressions. The chroma had a significant negative correlation (p<0.01) with tatal sugar, glucose, isomaltose and maltose. The stability had a significant negative correlation (p<0.01) with three carbohydrates except for isomaltotriose, and the correlation coefficient of glucose and the stability was0.930. There existed a significant positive correlation (p<0.01) with the viscosity and total sugar, glucose, maltose and isomaltose, and the correlation coefficient was0.922. |
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