Progress in Brewing Science and Beer Production.

The brewing of beer is an ancient biotechnology, the unit processes of which have not changed in hundreds of years. Equally, scientific study within the brewing industry not only has ensured that modern beer making is highly controlled, leading to highly consistent, high-quality, healthful beverages, but also has informed many other fermentation-based industries.

Beer consumers' perceptions of the health aspects of alcoholic beverages.

Consumers' perceptions about alcohol are shaped by numerous factors. This environment includes advertisements, public service announcements, product labels, various health claims, and warnings about the dangers of alcohol consumption. This study used focus groups and questionnaires to examine consumers' perceptions of alcoholic beverages based on their nutritional value and health benefits. The overall purpose of this study was to examine beer consumers' perceptions of the health attributes and content of alcoholic beverages. Volunteers were surveyed at large commercial breweries in California, Missouri, and New Hampshire. The anonymous, written survey was presented in a self-explanatory format and was completed in 5 to 10 min. The content and style of the survey were derived from focus groups conducted in California. The data are separated by location, gender, and over or under the age of 30. Parametric data on beverage rating were analyzed using analysis of variance (ANOVA) while the nonparametric data from True/False or Yes/No questions were analyzed using chi-square. Although statistically significant variances did exist between survey location, gender, and age, general trends emerged in areas of inquiry. The findings indicate that a great opportunity exists to inform consumers about the health benefits derived from the moderate consumption of all alcoholic beverages.

Beer and wine consumers' perceptions of the nutritional value of alcoholic and nonalcoholic beverages.

In general beer has not been portrayed as part of a balanced diet. However, red wine has been promoted as a beneficial part of a nutritious diet. The evidence is that beer is at least the equal of wine from a nutritional perspective and in countering ailments such as coronary heart disease. This study used surveys to compare beer and wine consumers' perceptions of alcoholic and nonalcoholic beverages. The consumers ranked 7 beverages based upon perceived healthfulness both before and after they were exposed to nutritional information about the beverages. The ranked data were analyzed using analysis of variance. The variance due to the 3-way interaction of place of recruitment, beverage, and ranking was found to be significant at P < 0.05. There was no significant difference between genders. Overall, consumers of alcoholic beverages perceived red wine to be more healthful than the other 6 beverages, including beer and white wine. The perceived healthfulness of a beverage does not appear to be the main factor driving the choice of beverage. Nutritional information does impact consumers' perceptions of the healthfulness of beverages. Consumers who are predominately beer drinkers were more heavily influenced by nutritional information than consumers who were predominately wine drinkers.

Use of novel assays to indicate that O-esters and S-esters are produced by the same enzyme in brewing yeast.

Ethanol- and methanethiol-dependent removal of acetyl-CoA by crude extracts of ale yeast has been monitored using a decrease in OD232. Activity has also been detected in these extracts after fractionation on polyacrylamide gels, in this case using a novel assay in which the coenzyme A produced in the reaction is linked via DCPIP reduction to color formation from nitroblue tetrazolium. Ethanol- and methanethiol-dependent activities migrate identically on such gels, and only one band of color formation was observed. Furthermore they displayed closely similar sensitivity to heating at 40 degrees C and 60 degrees C and pH optima, with activity maximal at pH 7.5. It is likely that a single enzyme is responsible for the formation of O-esters and S-esters in yeast. Initial kinetic studies indicate that methanethiol has higher affinity for the enzyme than has ethanol and a higher maximum velocity. However, the enzyme has a much lower Km for acetyl-CoA, suggesting that the alcohol or thiol substrate is the more likely substrate to be limiting.

Growth of Trichoderma viride on crude cell wall preparations from barley.

Trichoderma viride can utilize crude cell wall preparations from barley starchy endosperm as sole source of carbon and energy. In the process beta-(1-->3)(1-->4)-glucan and arabinoxylan are released. The onset of release of the latter preceded that of glucan, consistent with arabinoxylan being encountered and utilized first. The release of several enzymes was observed during growth of Trichoderma on this substrate: endo-beta-(1-->3)(1-->4)-glucanase, endo-beta-(1-->4)-glucanase, endo-xylanase, arabinofuranosidase, esterase, carboxypeptidase, and "beta-glucan solubilase". It is inferred that each of these activities is necessary for the digestion of this substrate.

The adaptability, purification and properties of exo-beta 1,3-glucanase from the fungus Trichoderma reesei.

The fungus Trichoderma reesei grows on barley (Hordeum valgare L.) beta-glucan and pachyman, secreting increased quantities of exo-beta 1,3-glucanase. This enzyme is also found in commercial cellulase preparations, from which it has been partially purified. It has a mol.wt. of 700000, an isoelectric point of 4.2, is cold-stable and hydrolyses both beta 1 Leads to 3- and beta 1 Leads to 6-linkages.

Structural aspects of the dye-linked alcohol dehydrogenase of Rhodopseudomonas acidophila.

1. A dye-linked alcohol dehydrogenase was purified 60-fold from extracts of Rhodopseudomonas acidophila 10050 grown aerobically on ethanol. 2. The properties of this enzyme were identical with those of the alcohol dehydrogenase synthesized by this organism during growth on methanol anaerobically in the light, and they are judged to be the same enzyme. 3. The enzyme gave a single protein band, coincident with alcohol dehydrogenase activity, during electrophoresis on polyacrylamide gel. 4. The amino acid composition, ioselectric point, u.v. and visible absorption spectra of the enzyme were determined and compared with those of other similar enzymes. 5. The presence of 0.7--1.0 g-atom of non-haem, acidlabile iron/mol of enzyme was shown by atomic absorption spectrophotometry and colorimetric assay. The iron could not be dissociated from the enzyme by dialysis against chelating agents. 6. E.p.r. spectroscopy of the enzyme did not indicate any redox function for the iron during alcohol dehydrogenation, but showed a signal at g = 2.00 consistent with the presence of a protein-bound organic free radical. 8. Antisera were raised against alcohol (methanol) dehydrogenases purified from Rhodopseudomonas acidophila, Paracoccus denitrificans and Methylophilus methylotrophus. 9. The antiserum to the Rhodopseudomonas acidophila enzyme cross-reacted with neither of the two other antisera, nor with crude extracts of methanol-grown Hyphomicrobium X and Pseudomonas AM1, thus emphasizing its singular biochemical properties.

Aerobic and anaerobic growth of Paracoccus denitrificans on methanol.

1. The dye-linked methanol dehydrogenase from Paracoccus denitrificans grown aerobically on methanol has been purified and its properties compared with similar enzymes from other bacteria. It was shown to be specific and to have high affinity for primary alcohols and formaldehyde as substrate, ammonia was the best activator and the enzyme could be linked to reduction of phenazine methosulphate. 2. Paracoccus denitrificans could be grown anaerobically on methanol, using nitrate or nitrite as electron acceptor. The methanol dehydrogenase synthesized under these conditions could not be differentiated from the aerobically-synthesized enzyme. 3. Activities of methanol dehydrogenase, formaldehyde dehydrogenase, formate dehydrogenase, nitrate reductase and nitrite reductase were measured under aerobic and anaerobic growth conditions. 4. Difference spectra of reduced and oxidized cytochromes in membrane and supernatant fractions of methanol-grown P. denitrificans were measured. 5. From the results of the spectral and enzymatic analyses it has been suggested that anaerobic growth on methanol/nitrate is made possible by reduction of nitrate to nitrite using electrons derived from the pyridine nucleotide-linked dehydrogenations of formaldehyde and formate, the nitrite so produced then functioning as electron acceptor for methanol dehydrogenase via cytochrome c and nitrite reductase.

The dye-linked alcohol dehydrogenase of Rhodopseudomonas acidophila. Comparison with dye-linked methanol dehydrogenases.

1. A dye-linked alcohol dehydrogenase was purified 20-fold from extracts of Rhodopseudomonas acidophila 10050 grown anaerobically in the light on methanol/HCO3-. 2. The enzyme resembled many previously reported methanol dehydrogenases from other methylotrophic organisms in coupling to phenazine methosulphate, requiring ammonia as an activator, possessing a pH optimum of 9 and a mol.wt. of approx. 116000. In many other respects the enzyme showed singular properties. 3. The stability of the enzyme under various conditions of temperature and pH was studied. 4. Primary aliphatic amines containing up to nine carbon atoms (the longest tested) were better activators than ammonia. 5. A wide range of primary alcohols and aldehydes served as substrates, with apparent Km values ranging from 57 mM for methanol to 6 micron for ethanol. 6. O2 was an inhibitor competitive with respect to the alcohol substrate. In the presence of O2, apparent Km values of 145 mM were recorded for methanol. 6. Cyanide and alphaalpha'-bipyridine were inhibitors competitive with respect to the amine activator. 7. The properties of the enzyme from Rhodopseudomonas acidophila are compared with those of similar enzymes from other organisms, and implications of the salient differences are discussed.

The molecular size of N-methylglutamate dehydrogenase of Pseudomonas aminovorans.

N-Methylglutamate dehydrogenase, purified to a specific activity of 0.29 unit/mg of protein, gave one band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, corresponding to a molecular weight of 130 000. Enzyme-Triton complexes were found to have a partial specific volume of 0.73 cm3/g, suggesting that the protein binds less than 0.1 g of Triton/g of protein. A molecular weight for the intact enzyme in the presence of 1% (w/v) Triton X-100 of 550 000 suggested that the enzyme may be a tetramer.

Solubilization, partial purification and properties of N-methylglutamate dehydrogenase from Pseudomonas aminovorans.

1. Extracts of amine-grown Pseudomonas aminovorans contained a particle-bound N-methylglutamate dehydrogenase (EC 1.5.99.5). The enzyme was not present in succinate-grown cells, and activity appeared before growth began in succinate-grown cells which had been transferred to methylamine growth medium. 2. Membrane-containing preparations from methylamine-grown cells catalysed an N-methylglutamate-dependent uptake of O2 or reduction of cytochrome c, which was sensitive to inhibitors of the electron-transport chain. 3. N-Methylglutamate dehydrogenase activity with phenazine methosulphate or 2,6-dichlorophenol-indophenol as electron acceptor could be solubilized with 1% (w/v) Triton X-100. The solubilized enzyme was much less active with cytochrome c as electron acceptor and did not sediment in 1 h at 150000g. Solubilization was accompanied by a change in the pH optimum for activity. 4. The solubilized enzyme was partially purified by Sepharose 4B and hydroxyapatite chromatograpy to yield a preparation 22-fold increased in specific activity over the crude extract. 5. The partially-purified enzyme was active with sarcosine, N-methylalanine and N-methylaspartate as well as with N-methylglutamate. Evidence suggesting activity with N-methyl D-amino acids as well as with the L-forms was obtained. 6. The enzyme was inhibited by p-chloromercuribenzoate, iodoacetamide and by both ionic and non-ionic detergents. 2-Oxoglutarate and formaldehyde were also inhibitors. 7. Kinetic analysis confirmed previous workers' observations of a group transfer (Ping Pong) mechanism. 8. Spectral observations suggested that the partially purified preparation contained flavoprotein and a b-type cytochrome. 9. The role of the enzyme in the oxidation of methylamine is discussed.