The malt alkaloids N-methyltyramine, N,N-dimethyltyramine (hordenine), N-methyl-3-aminomethylindole and N,N-dimethyl-3-aminomethylindole (gramine) are known precursors for N-nitrosamines. Analytical procedures were developed and applied to extract and quantify these alkaloids from malt, green malt, malt roots, and raw barley. A ground malt sample under nitrogen atmosphere was extracted with 5 percent concentrated ammonium hydroxide in methanol at room temperature for 24 hours. After purification, the extracted alkaloids were quantitated by reverse phase high performance liquid chromatography using both phosphate buffer and ion-pairing solvent systems. The recoveries obtained for the alkaloids listed were, respectively, 77.4, 92.0, 74.0 and 80.5 percent with detection limit of 0.2, 0.2, 0.1 and 0.1 μg/gm. Conformation of identity of each alkaloid was accomplished by TLC, UV, and MS. Twenty-three samples of kilned malts, five samples of green malts, ten samples of kilned malt roots, five samples of green malt roots, and ten raw barley samples, from a total of 11 varieties of Hordeum vulgare were analyzed for the alkaloids of interest. N-Methyltyramine was found in every sample from all sources with a mean and range, respectively, of 26.8 (15.7-48.5), 21.4 (11.6-37.5), 1959.8 (1358.4-2798.4), 1532.5 (962.3-2091.1) and 4.7 μg/gm (0.4-17.9 μg/gm) on a dry weight basis. The means and ranges for hordenine were, respectively, 28.1 (8.9-42.4), 21.2 (9.6-35.5), 4066.4 (2741.2-5180.1), 3363.3 (1956.2-4744.3) and 0.7 μg/gm (0.5-1.0 μg/gm). Gramine was found in only two barley malt varieties examined where kilned and green malts contained, respectively, mean values and ranges of 7.4 (4.9-10.0) and 6.0 μg/gm (4.7-7.3 μg/gm). N-Methyl-3-aminomethylindole was not detected in any of the samples examined. The results of this investigation indicated that the variety of barley affected alkaloid production during malting. The results also showed that the kilning step of the malting process increased the total amount of each alkaloid produced. Finally, room temperature nitrosation of five varieties of kilned and green malts, in which the contents of hordenine and gramine were known, was carried out with an excess of nitrite in acetic acid at pH 3.2 for 18 hours. The amounts of N-nitrosodimethylamine (NDMA) obtained from this nitrosation were far greater than the expected yields for NDMA from the hordenine and gramine present in the malts. The results strongly suggest that the alkaloids hordenine and gramine were not the only precursors for NDMA and that there must be additional precursors; dimethylamine was suggested as a possibility. / Graduation date: 1984

Texte remanié de: Habil.-Schr.--Berlin--Freie Universität, 1994. / Bibliogr. p. [445]-456.

Thesis (Ph. D.)--Universität Leipzig, 1906. / Vita. Master Negative No. 96-0111. Filmed with: Der Siebenschläfer / Franz Adam Beyerlein. Includes bibliographical references (p. [9]-10).

Thesis--PlanA (M.S.)--University of Wisconsin--Stout, 2003. / Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

When filtering beer at pore sizes of 0.45 μm and below, some desirable components may be lost, even though they are orders of magnitude smaller than the pores. In this work, a model beer solution of pure components has been filtered through 0.2 μm membranes to investigate this problem. Starch (a model for the long chain carbohydrates) at a concentration of 1500 mg.l-1 and casein (a model for the protein fraction) at a concentration of 150 mg.l-1 were found to result in reduced permeate fluxes in the region of 20–40 l.m-2.h-1.

The beer market in China is highly-localized: retail channels are very complicated and most local consumers prefer local beer brands, which means both global and local beer maker are facing great challenge doing business in China. The study exams Tsingtao Beer¡¦s three major changes: acquisition, integration and international activities and connects these changes to hyper-competition advantages to explain why Tsingtao Beer is the leader in China's beer market.

Thesis (doctoral)--University of Helsinki, 2009. / Includes bibliographical references. Also available on the World Wide Web.

Inaug.-Diss.--Philosophische Fakultät--München--Ludwig-Maximilians-Universität, 1987.

Thesis (doctoral)--Universität, Wroclaw. / Includes bibliographical references (p. [177]-196).