Research On The Organic Acid Composition In Beer

Organic acids were one of the most important flavor compounds in beer. 6 kinds of organic acids (pyruvic acid, malic acid, lactic acid, acetic acid, citric acid and succinic acid) presented in beer were intensively studied in this paper. The relative optimal ranges of organic acids in light beer were determined by measurement and statistic analysis of the content of organic acids in commercial beers. The change and influencing factors of organic acids content during brewing process were investigated systematically in this study. The organic acids content of final beer were improved and controlled by adjusting the malting, mashing and fermentation processing with Gan 3 malting barley.Organic acids in final malt were largely produced during germination. The total content of organic acids was increased by 3 times compared with the raw malting barley. The content of acetic, lactic and succinic acid in malt was increased by 20.9, 7.7, 5.9 times, respectively. The level of succinic acid was increased gradually with malting time and more rapidly in kilning processing. The notable increasing in citric and pyruvic acid content but lowered slightly in kilning were also observed. The malic acid content was fluctuated throughout the malting. Barley variety, malting procedure and microorganisms were the key factors influencing the content of organic acids in final malt.The improved malting parameters for domestic barley variety Gan 3 were as follows: raw barley was washed by 0.06 % NaOH and 1.0 % NaClO solutions, steeping time was 37-hour, then germinate at 15℃(humidity 90%) for 5 days. The kilning temperature was 83℃for 3-hour. The content of organic acids in final malt was improved.Organic acids were the main components of origin total acids in malt. They were dissolves into wort at the beginning of mashing process. The content of organic acids in wort was greatly influenced by rice, wort boiling type and additives. The organic acid content in wort was decreased by 10 % with 30 % rice adjunct. The total content of organic acids in wort was decreased by 23 % with adding hops and Ca2+ in the open kettle boiling system, while the content of acetic, pyruvic and malic acid was lowered by 65 %, 27 % and 22 %, respectively.The amounts of organic acids in 45 commercial beers bought from Wu xi market were determined. The great discrepancy in content of organic acids between Chinese and foreign beers was indeed presented. With measured of the organic acid contents in 23 foreign beers and many Budweiser samples, the relative optimal range of organic acids was considered as: pyruvic 50-70 mg/L, malic 60-80mg/L, lactic 60-80 mg/L, acetic 20-40 mg/L, citric 110-130 mg/L and succinic acid 50-80 mg/L. A comprehensive evaluation method by the content of six organic acids was proposed with statistic methodology. The beer could be ranked and compared by the organic acid content in beer.Rice (30%) and malt (70%) were used to prepare 14 Plato high-gravity wort, the mash process was finished ( protein rest at pH 5.4 ) at 50℃for 40 min, then 3# yeast strain (15×106cell/mL) was pitched, main fermentation at 10℃, finally green beer was diluted to...