| Beer is one of the most important low alcohol beverages in the world. In this research, real attenuation, the content ofα-AN and dosage of wheat malt were studied to investigate the effects of 8oP beer's brewing. The main results were as follows:1 Four beers (the real attenuations was 57.6%, 63.4%, 67.9%, 72.5%, respectively) were brewed by bottom fermentation using 7oP wort. The brewing were carried on under same conditions while some indexes including total acid, pH value,α-AN, alcoholic, reducing sugar and real extract content were determined at one day interval during the main fermentation. After one day's lag phase, the total acid decreased firstly and then increased after two days fermentation. The pH value,α-AN, reducing sugar and real extracts content decreased gradually while alcoholic continuously increased. The residueα-AN of finished beer enhanced with the increasing of real attenuation, which was equal to 12.3%～19.4% that of wort; The pH value was decreased by 1.79~1.89; Total acid and residue reducing sugar enhanced with the increasing of real attenuation and their contents were 0.62~0.77 mL/100mL 0.1mol/L NaOH and 3.2~4.80g/L, respectively. Turbidity of beer decreased with the increasing of real attenuation and the chroma didn't change significantly. Sensory evaluations show that 8oP beer with 57.6% real attenuation had best sensory quality.2 Four 8oP beers (real attenuation was 57.6%, 63.4%, 67.9% and 72.5%, respectively) were brewed by bottom fermentation method. Nine organic acids in beers were detected by reversed phase high performance liquid chromatography (The recovery of addition standards were 92.07~108.85 and coefficients of variation were 0.803~1.706). The buffer capacity of beers was detected too. Correlativity between organic acids and buffer capacity was analyzed by SAS 9.0. The conclusions were that lactic acid had great significant correlation with buffer capacity and the correlation coefficient was -0.99008 (P﹤0.01);α-ketoglutaric acid had significant correlation with buffer capacity and the correlation coefficient was -0.96944 (P﹤0.05); fumaric acid, succinic acid had commonly correlation with buffer capacity and the correlation coefficients were 0.91313,0.93816 (P﹤0.10) respectively.3 Six 8oP beers (α-AN of wort were 109.0, 120.5, 130.1, 139.3, 148.5, 159.5mg/L, respectively, which were adjusted by yeast nutriment ) were brewed by bottom fermentation method. Relationships between wortα-AN and their physical and chemical index, such as original gravity (7.86~8.10oP), alcohol content (3.71~3.83%, v/v), real attenuation (58.13~59.20%), were analysed by SAS9.0. The results indicated that there were significant correlations between wortα-AN and original gravity, real gravity, and chroma (P<0.05). And wortα-AN positively related with reducing sugar of beers (P<0.1). The total acid (1.40~1.70mL/100mL 0.1mol/L NaOH) had commonly correlation with wortα-AN (P<0.1). The total nitrogen,α-AN had extremely significant positively related with the wortα-AN (P﹤0.01).Flavor matters including alcohols, aldehydes, ketones, esters, acids, alkanes were detected by gas chromatography. Correlativity between all flavor matters andα-AN contents were analyzed by SAS 9.0. The conclusions were that isobutanol and isovaleric acid had very significant correlation withα-AN (P﹤0.01); alcohol + isopentanol, ethyl heptanoate, caprylic acid, tetramethylpyrazine significant correlation withα-AN (P﹤0.05); acetaldehyde, acetoin, heptoic acid had commonly correlation withα-AN (P﹤0.1). Sensory evaluation showed that the beer with 120.5 mg/Lα-AN had the best flavor.4 Five 8oP worts were prepared by using different dosage of wheat malt (0%, 5%, 10%, 15%, 20%) in saccharification and the indexes were analyzed. With the increasing dosage of wheat malt, Arabinoxylan andβ-glucan had an ascending tendency, viscosity increased gradually while filtration rate decreased, reducing sugar andα-AN showed a decreasing tendency. Correlativity between each index of wort and the dosage of wheat malt and indexes of wort were analyzed by SAS 9.0. The conclusions were that there better correlation between each index and dosage of wheat malt and each index. Sampling and analysis of each temperature point in saccharification curve, the maximum content of Arabinoxylan was found at 52℃(1556.25~1601.56mg/L);β-glucan had the maximum content at 78℃(57.45~82.02mg/L) and reducing sugar had similar content at 63℃, 72℃,78℃(31.54~42.62g/L).5 Four 8oP worts were prepared by using 5%, 7%, 8.5% and 10% wheat malt dosage, inoculated with bottom beer yeast. The research results showed that adding up to 10% of wheat malt did not affect the flavor compounds such as alcohols, aldehyde acid, and organic acids, and esters. And it did not affect the sensory characteristic of beers.
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