Study On Low-purine-compound Beer

The content of purine compounds in common beer was about 40-100 mg/L which could have the side effect on human's healthy. The purine compounds content of 10oP beer was decreased to about 10 mg/L successfully with high proportion of adjunct, high gravity brewing technique and sorbent in this paper.Firstly, the analysis method of purines in beer was established with the reverse- phase ion pair chromatography (PR-IPC). Purine compounds in beer were prehydrolyzed to purines by perchlorate acid, the optimal hydrolysis condition was as follows: the ratio of beer to perchlorate acid was 1:2, hydrolysis at 100℃for 30 minutes. The optimized chromatography condition was: 254 nm by UV detector with water:methyl alcohol: acetic acid: tetrabutylammonium hydroxide (897:100:1.5:1.5) as mobile phase and flow rate at 1 mL/min. The average recovery of four purine bases was 98.2 %-100.3 %, while the accuracy of the method as RSD of all four purine bases was 1.41 %-2.42 %.Most purine compounds in beer were originated from malt, and little from finely-made adjunct such as rice. Purine bases in wort could be used by yeast, and firstly the aim of mashing processing was that the content of purine bases in wort was the most. The relatively optimized mashing processing was: adding malt rootlet 1.5% and Ca2+ 50 mg/L,protein rest at 45℃for 30 minutes, brewing temperature at 68℃, pH 5.6-5.8 adjusted by orthophosphoric acid, the ratio of malt to water was 1:3.5. The purine compounds content was increased from 30.7 mg/L to 57.9 mg/L.The main and effective method for decreasing the purine compounds content in beer was used high proportion adjunct combined with high gravity brewing. The proportion malt was decreased to about 25% and the gravity of wort was 18-20oP, the yeast was pitched with reused one just after main fermentation with 2.4×107/mL, and 0.15mg/L Zn2+ was added in the wort. At the same time, the wort turbidity was controlled much higher than the normal. The fermentation situation was successful.The purines compounds content in 10oP beer was decreased to less than 30 mg/L after fermentation.Different sorbents were used to absorb purines compounds in this paper. It was shown that the total purine compounds content in the commercial beer was decreased 75% and 65%, respectively, with activated charcoal and zeolite as the sorbent. The bitterness unit and color was decreased. The pilot experiment was carried out with 15 L EBC tube. The purine compounds content in the beer was 10.5 mg/L and 12.1 mg/L, respectively, which was reached the goal. The parameters of the beer were according with GB4927-2000.