The Feasibility Study Of Beer Sterilization By Ultra-High Pressure Water Jet Technology

Object: At present, principle sterilization procedures adopted by beer industry almost have some disadvantages. So, It is necessary to find a new sterilization procedure which can realize energy saving and environment protection. This project put a new sterilization method——ultra-high pressure water jet technology into the field of beer sterilization uniquely, then made feasibility study on several aspects in order to provide experimental evidence and technical support for exploiting new sterilization procedure of beer.Method:To treat the fresh beer, that experienced no sterilization, with the ultra-high pressure water jet. Collect the samples at different pressures of0.1MPa (the original sample as control),50MPa,100MPa,150MPa,200MPa,250MPa and300MPa.①To discuss the impact on the major spoilage bacteria in beer (lactobacillus) and the required detecting item in hygienic standards of fermented wine (coliform bacteria) underwent sterilization cycle of ultra-high pressure water jet.②To establish a static headspace gas chromatography (SHS-GC) method for investigation of the changing profiles of flavor compounds resulted from different sterilization patterns. Meanwhile, feasibility of the sterilization procedure with ultra-high pressure water jet can be evaluated.③To evaluate flavor staling with TBA level in beer underwent sterilization procedure by ultra-high pressure water jet technology.④To detect the content of high molecular weight protein in beer samples by the method of Coomassie brilliant blue and evaluate foam stability using stop watch. And also disscuss the impact of beer foam-active protein and foam stability underwent ultra-high pressure water jet sterilization.Result:①The results of sterilization study showed that it could be satisfy the hygienic standard of fermented wine about coliform bacteria if beer sterilized by ultra-high pressure water jet.When reaches a pressure of150MPa, the ultra-high pressure water jet sterilization cycle can effectively kill the major spoilage bacteria in beer(the lactic acid bacteria).②The static headspace gas chromatography (SHS-GC) method which we established is of-high specificity, excellent spiking recovery and precision. And it is easy to use for determining three kinds of alcohols and four kinds of volatile esters in beer samples. The measuring range of the ingredients in beer sample were list as follows:6.13～11.85mg/L for propyl alcohol,5.81～6.96mg/L for isobutyl alcohol,28.37～35.71mg/L for isoamyl alcohol,9.84～18.04mg/L for ethyl acetate,0.024～0.047mg/L for butyl acetate 0.72～1.51mg/L for isoamyl acetate and0.35-2.44mg/L for ethyl hexanoate are detected in the beer samples underwent different pattern of sterilization cycle. The content of higher alcohols were nearly in the optimal scope, which showed that ultra-high pressure water jet sterilization can control the content of higher alcohols efficiently. As to volatile esters, the sterilization pressure must be controlled in the range from150to200MPa, these above four kinds of volatile esters can demonstrate their favorable contribution to beer flavor.③The result of flavor staling study showed that increased pressure could intensify the oxidation of the carbonyl compounds in the beer and result in flavor staling.④Sterilization by ultra high pressure water jet could kill the microorganisms in beer without effected the content of high molecular weight protein in beer. What ’ s more, the foam persistent time and wall-adhere time were significantly longer than high temperature short time(HTST) sterilization beer from the same bacth.⑤. From synthetic results, we preliminary consider that when reaches a pressure of150MPa, the ultra-high pressure water jet sterilization cycle can get well effect, lower energy consumption and smaller negativet influence.Conclusion:This above results preliminary shows the feasibility to put ultra-high pressure water jet procedure into the field of beer sterilization. The energy saving and environment protection ultra-high pressure water jet sterilization will be a new sterilization procedure of beer.