Research On Sour-Taste Substances In Wheat Beer

The main substances which had an effect on sour-taste of wheat beer were studied in this paper. Five kinds of sour-taste substance (malic acid, lactic acid, acetic acid, citric acid and succinic acid) presented in wheat beer were intensively studied. With measured of the acid contents in German high-grade wheat beers and many licher samples, the relative optimal range of organic acids was considered as: malic acid 70-100mg/L, lactic acid 85-120 mg/L, acetic acid 85-105 mg/L, citric acid 150-180 mg/L and succinic acid 95-120 mg/L.Wheat variety, and malting procedure (steeping process, germinating temperature and kilning temperature) were the key factors influencing the content of sour-taste substance in final malt. The contents of acetic, lactic, citric acid and succinic acid in wheat malt by micromalting, increased by 11.2, 6.1, 7.0 and 4.7 times, respectively. The level of citric acid and succinic acid increased gradually with malting time and increased more rapidly in kilning processing. The malic acid content had been in a dynamic equilibrium throughout the malting. During wheat beer brewing process,raw materials played primary role on sour-taste of beer. The improved malting parameters for wheat malt from Malteurop (Baoding) Malting Co.,Ltd., were as follows: raw barley was washed by 0.13 % NaOH and 0.05% Bleaching Powder, steeping time was 32 h, then germinated at 15℃(humidity 95%) for 5 days. The kilning temperature was 85℃for 2 h. Eventually, the general indexes of final malt were up to the mustard, and its sour-taste was improved.Furthermore, both fermentation and mashing conditions had greater influence on sour-taste of wheat beer. When changing in the full measure of its volume, mashing process which leaded to change in acids content of wort do not impact a lot on the content of organic acids in wort. Rice (30%), barley malt (20%) and wheat malt (50%) were used to prepare 11 oP wort, the mashing process was finished at 50℃for 15 min, then 1# yeast strain and the best fermentation parameters were obtained as follows: inoculation of 1.0×107 cell/ mL, the main fermentation temperature 9℃for 5 days, back fermented in 4℃for 3 days and then stored at 0℃for 3 d.Finally, the raw material of wheat malt made from the better malting process were used in the experiment with the optimized mashing process and fermentation process. All the measures declined sour-taste in wheat beer. The content and proportion of sour-taste substances in wheat beer were close to the optimum range determined. The wheat beer was tasted with full-bodied and moderate by the sensory evaluation.