Study On Brewing Draft Keg Conditioned Wheat Beer

Nowadays the consumers pay more attention to qualities of beer, especially the taste and nutrition, along with the development of society. And the technology and quality of products are indeed improved in order to meet the needs and wants of the consumers. In facet, there are all kinds of draft beer in the market, including bottled draft beer and cask draft beer and so on. Howerver, there are varying degrees of defects.A novel approach for preparing draft keg conditioned wheat beer was developed by the method of second fermentation in kegs, which was described in the thesis. The producing processes were as follows. The beer was brewed with 40% wheat malts and 60% barley malts. 4-vinylguaiacol(4-VG), which is an important flavour-active volatile phenol in wheat beer, was increased adopting the optimized mashing process. Then top-fermenting yeasts No.303 were used for brewing the beer as primary fermentation in the main fermenter at the fermentation temperature 22℃. When the residual extract was 3.8°P, the primary fermentation ended. The green beer was centrifuged to remove the top-fermentating yeasts No.303. Then the fermentable extract and bottom-fermenting yeasts No.308 were added into the beer for keg conditioning. The final concents of the fermentable extract and the number of bottom-fermenting yeasts No.308 were 1.5% extract and 8×10~6-1×10~7 /mL. Then the green beer was sterile kegged immediately. The keg conditioning was divided into two stages. To begin with, the beer was held in the keg at temperatures between 18 and 19℃for 7 days, then cold stored at temperatures ranging from 8 to 6℃for 14 days.Then we get the draft keg conditioned wheat beer with the alcohol content of 4.5~6.0%(v/v), and the original gravity was 11.0~12.5°P. While in the keg, the remaining extract and new extract fermented by bottom-fermenting yeasts No.308, so that the oxygen in the keg was mostly removed. That was why we could overcome the natural disadvantage that the beer was oxidated because of containers. Also the beer was further carbonated. Since the process of pasteurizing could not be used, there were living yeasts including in the beer. The beer prepared by the above technique is rich in nutrition, with a lot of white and exquisite foam, as well as a specific taste of wonderful freshness and flavor characteristics.The products were successfully developed with our help on January, 2008. Then its first products went on sale. After one year of production and operation, the products were accepted by most consumers. They all believe that the beer was of top grade, not only excellent in quality but also reasonable in price. Practice has proved that this products would have good market prospects and economic benefits.