Abstract: In this paper, wort, fermenting liquor and beer were determined by HPLC, and the change of purines in fermentation process was analyzed, and proposed the effective control measure and to improve it. By the ultraviolet mutagenesis of the saccharomycetes protoplast, screening produces the purine low strain. Take pH = 3.85 to the 0.02 mol/L phosphate buffer solution as the mobile phase liquid, and the Wavelength is 254 nm for test. The experiments show that, the conditions of protoplast’s formation is use the 1.5% of the snail-as-broken ,and 0.7mol / L of sucrose buffer for hypertonic pressure stabilizer, bath processing 3-4h in 30 ℃ water .And the conditions of UV-induced is in the ultraviolet light irradiation of 25W, Mutation 60s to make the protoplast death rate more than 80%,and the reproducibility is 5.6%. Repeated siftings and fermentation. The purine in beer content lower than the ordinary one. The research in this paper offered a reliable analytical method and the researching direction of low—purine beers．
Keywords：Yeast ;Protoplast; Mutagenesis; Highly effective liquid chromatography; Purine
