The Correlations Between Sensory Evaluation And Intrinsic Quality, Physiochemical Indexes Of Daqu

Daqu is the driving force for liquor production, which act as a carrier rich in multiple microbes, various enzymes and composites. A lot of famous liquor-making enterprises take Daqu as raw material of liquor production. Liquor yield and liquor quality are greatly affected by the quality of Daqu. Even if the quality of Daqu is so important but in the current production Daqu is still evaluated mainly by sensory indexes. In order to make a scientific evaluation system for Daqu quality the correlations between sensory evaluation and intrinsic quality, physiochemical indexes of Daqu should be clearly investigated. Based on this, two strong-flavour type Daqu with different sensory characteristics from Luzhou Laojiao were selected and a systematic comparative analysis on microorganism system, enzyme system, and multiple physiochemical indexes were made in this paper.On the basis of Luzhou Laojiao Daqu standard, two different kinds of Daqu were selected in accordance with the appearance, section and flavor. The amount of bacteria, bacillus, mold and yeast in high quality Daqu (HQD) were higher compared with those in common quality Daqu (CQD). The analysis of physiochemical ingredients illustrated that acidity of HQD was higher than that of CQD, but starch and protein content were lower compared with those in CQD. The main enzyme activities of HQD were higher than those of CQD.Esterifying power and ethnol productivity of HQD were all higher than those of CQD. And the esterifying power of HQD from high-temperature Daqu was almost two times than that of CQD. But the rate of breaking-up of HQD was less than that of CQD. Besides, total free amino acids of HQD was higher than that of CQD too. And umami amino acids of HQD such as glutamic acid and aspartic acid were a little more than those of CQD while umami amino acids of HQD were significantly higher than those of CQD.A method for determining volatile components of Daqu was established by headspace solid-phase micro-extraction(HS-SPME) coupled with capillary gas chromatography-mass spectrometry(GC-MS). The effects of extraction time, extraction temperature, fiber coatings on volatile components were investigated. The volatile components of Daqu were extracted better by capillary gas chromatography-mass spectrometer. The method was characterized by the good repetition and higher recovery rates. Volatile components of Daqu were calculated accuratly by the method. The volatile components of Daqu were analyzed by HS-SPME coupled with GC-MS.From different quality of the middle and high-temperature Daqu 77 volatile compounds were detected. The average total amount of volatile compounds of HQD was higher than that of CQD. Alcohols was the highest content in CQD while esters highest content in HQD. The average content of esters of HQD was 1.26 times that of CQD. There was no much difference in total content of between pyrazines, aldehydes, ketones and aromatic compounds. The average content of acids in HQD was 3.3 times that of CQD. The average content of other heterocyclic compounds was 52.61μg/kg, which was higher than the average content of 30.08μg/kg in CQD significantly. From different quality of high-temperature Daqu 87 volatile compounds were detected.The average total amount of volatile compounds in HQD was 1.57 times that of CQD. The level of alcohols was the highest in CQD while the content of aldehydes and ketones was the highest in HQD. The average level of aldehydes and ketones was 1814.30μg/kg while that of CQD was 990.35μg/kg. The average content of esters in HQD was 1.98 times that of CQD, and meanwhile the average total content of pyrazines and acids in HQD were almost 2 times that of CQD in their respective. The average level of aromatic compounds in HQD was 1029.93μg/kg while that of CQD was 658.05μg/kg. There was no much difference in the average total content of alcohols and phenolic compounds.Brewing experiment was conducted using different quality of Daqu. The results showed that the total content of acids,_esters and free amino acids in liquor produced by HQD were better than those in liquor produced by CQD.