| Daqu is a saccharifying and fermenting agent for the production of daqu liquor, a traditional and popular distilled alcoholic beverage in China. In the daqu preparation, the microbes in the surrounding environment were selectively gathering, reproducing and propagation at the solid-state fermentation. So, it is a crude microbial originated enzyme preparation and often has a brick-like shape. Which provides a microbial resource for saccharifying and fermentation and has a huge impact on the characteristic aromatic quality and yield of the final Chinese liquor. Tea flowers, the reproductive organ of tea plants, are abundant in tea plantation, and have a long flowering period, short life and low seeding rate. They have various beneficial active ingredients that are similar to those in tea leaves, which provide their biological effects such as detoxification, anti-oxidation, anti-aging and anti-cancer. Those indicate the applications of tea flowers are prospective.As a novel food approved by Ministry of Health in 2013, the researches in tea flowers are still in the preliminary stage of exploration. Due to the strong aroma of tea flowers, we were attempted to combine tea flowers with a traditional daqu maternal starter to produce a new-type daqu to make a new-style daqu liquor with a special aroma.With a traditional solid-state fermentation technique, tea flowers were introduced to make a novel daqu together with wheat and maternal starter. Based on the results from single factor tests, the technical parameters of tea-flower daqu were optimized by means of orthogonal tests. The results had showed that, when additive amount of the tea-flower to wheat at 2.0%, additive amount of maternal starter and water at 3.0%, and 45%, respectively, the finished daqu products after 25-days ripening culture had an uniform white plague and mycelia on the surface without splits, and sharp cross-section. They also had obvious burning circles and full of strong daqu fragrance without off-flavors. Those tea-flower daqu had moisture content at 12.5g/100g, starch content at 52.53g/100g and acidity at 0.9 mmol/lOg. The power of saccharifying, liquefaction and fermentation were 816.5mg/g-h, 1.1g/g-h,57gCO2/100g-48h, respectively. The mold, yeast and bacteria in those daqu were 9.8 X 106,9.4 X 105 and 5.7 X 106cfu/g, respectively. The main aroma components in tea-flower daqu were detected by headspace method with GC-MS. The results showed that, compared to the tea-flower daqu,48 species of aromatic components were determined, included alcohols, aldehydes, ketones, alkyl alkynes, terpenes, nitrogens, acids, aromates, phenols, esters and furan. Compared with those in the control group and the daqu maternal starter, the tea-flower daqu had some aromatic substances such as acetophenone and alpha benzyl ethanol, and special tea compounds caffeine from tea flowers were detected.Finally, the traditional daqu liquor making technique had applied to prepare the tea-flower daqu liquor. The sensory and physicochemical indicators of this novel daqu liquor were clear without suspended solids and precipitation, colorless, fragrant and pure. The taste was soft and harmonious. The style was similar to fen-flavor liquor, a kind of mild aromatic flavor liquor. The alcoholic strength was 33%(v/v), solid content was 0.55g/L. The aromatic substance of tea-flower daqu liquor had 40 species with total content of 11020.89mg/L and ethyl acetate had the highest amount at 2624.21mg/L. Those indicat that the tea-flower daqu are more suitable to be make fen-flavor liquor. |
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