Sweet Wort Research Articles

Metodika stanovení prolinu ve sladině.

Metodika stanovení prolinu ve sladině.

The Effect of Some Physical Factors on the Chlamydospores and Mycelium of Loose Smut of Wheat - Ustilago iritici (Pers.) Rostr.

Summary Trials were undertaken to study the direct effect of different temperatures and time of exposure under anaerobic conditions on the chlamydospores and mycelium of loose smut of wheat — Ustilago tritici (Pers.) Rostr. — with different moisture contents. Several different laboratory techniques were employed to test the effect of anaerobic conditions on loose smut of wheat. The chlamydospores of loose smut of wheat, used in the trials, were of various origin. Chlamydospores from the ears of different wheat varieties were tested. They were 1–5 months old, and kept at the temperatures ranging from 8 to 20 °C during storage. No chlamydospore germinability and no wheat loose smut mycelium growth were observed during exposure to anaerobic conditions. When the exposure to anaerobic conditions was stopped and the chlamydospores and mycelium were subjected to aerobic conditions (grown in Petri dishes on sweet wort agar), the chlamydospore germination and mycelium growth were found to be inhibited, or the parasite was killed. It was found that there were some correlations between the mentioned factors affecting loose smut. Anaerobic conditions were more effective when the temperatures and the moisture levels in the spores and mycelium were higher and the time of exposure longer. The study has yielded new findings supporting our theory ( Ujevic 1958) according to which the mycelium of loose smut in grains is killed as a result of a direct complex and selective effect of the mentioned factors on the parasite. Our theoretical conclusions differ from the to-date theory asserting that the parasite mycelium is killed by the toxic substances produced in grains during seed disinfection by some physical methods.

The Effect of Different Temperatures, Moisture Content, and Different Time of Exposure under Anaerobic Conditions on the Chlamydospores and the Mycelium of Loose Smut of Barley - Ustilago nuda (Jens.) Rostr.

Summary A study was undertaken to examine the direct effect of different temperatures and expotsure time under anaerobic conditions on the chlamydospores and the mycelium of loose smut of barley (Ustilago nuda Jens. Rostr.) having different moisture content. Various laboratory techniques were employed in the study of the effect of anaerobicconditions on loose smut. Chlamydospores of loose smut of barley of different proveniances were used in the trials.Chlamydospores from the ears of various barley varieties (Valtický, Jantar, Branisovický) and a mixture of chlamydospores from more ears of different varieties were examined. The chlamydospores, 1-5 months old, were stored at a temperature of 4 °C and 20 °C. In no case, the study revealed any capability of the germination of the chlamydosporesand growth of the mycelium of loose smut of barley under the effect of anaerobic conditions. When the chlamydospores and the mycelium of loose smut were placed into aerobicconditions after the exposure to the anaerobic conditions had been stopped (then they were cultivated in Petri dishes on sweet wort agar), the inhibition of the germination of chlamydospores and the growth of mycelium — or even the killing of the parasite — was observed. It has been found that there is a positive correlation between the mentioned loose smut controlling factors. Anaerobic conditions became more effective with the rising of temperature, with theincreasing moisture content of spores or mycelium, and with the increasing time of action.

Stanovení poměru redukující oligosacharidy/monosacharidy ve sladině.

Stanovení poměru redukující oligosacharidy/monosacharidy ve sladině.

STRUCTURAL ANALYSIS OF WORT DEXTRINS BY MEANS OF β-AMYLASE AND THE DEBRANCHING ENZYME, PULLULANASE

Dextrins from a sweet wort, prepared by infusion mashing, were fractionated by paper chromatography according to their molecular weights and further into linear and branched dextrins. Each fraction was treated with β-amylase and with the debranching enzyme, pullulanase. The products of this enzymic hydrolysis were identified by paper chromatography. From the pattern of oligosaccharides so obtained, structures have been postulated for the dextrins with a degree of polymerization of 4 to 8 glucose units. The linear dextrins, maltotetraose, maltopentaose, maltohexaose, maltoheptaose, and malto-octaose, were shown to be present in wort. In addition, at least eleven branched dextrins were found: 62-α-maltosyl-maltose, 6-α-glucosyl-maltotriose, two branched pentasaccharides, two branched hexasaccharides, two branched heptasaccharides and three branched octasaccharides.

THE FATE OF AMINO ACIDS DURING MASHING AND HOP BOILING

In an infusion mash system the concentration of all α amino acids in sweet wort reaches a maximum value when approximately one-third of the total volume extracted has been run from the mashing vessel. The relative concentrations of each α amino acid in wort vary throughout the mash tun extraction owing to differences in rate of extraction of the amino acids and to the quantities produced by peptidase activity in the mash tun. The relative proportions of proline, alanine, glutamine and asparagine in the total α amino nitrogen content of wort decrease appreciably as the mashing process proceeds. Copper boiling results in the partial destruction of methionine, glutamic acid, lysine, arginine and valine present in sweet wort together with an increase in the concentration of ammonium ion in the wort.

TRACE VOLATILE CONSTITUENTS OF BEER IV. VOLATILE ACIDS

Eighty-one volatile acids have been detected in the sodium bicarbonate solubles of an ethereal extract of beer, and they together account for 65% of the total ether-soluble acids. Acids positively identified are methanoic (formic), ethanoic (acetic), n-propanoic (propionic), n-butanoic (butyric), 3-methylpropanoic (isobutyric), n-pentanoic (n-valeric), 3-methylbutanoic (isovaleric), n-hexanoic (caproic), hex-2-enoic, hex-3-enoic, n-octanoic (caprylic), n- nonanoic (pelargonic), n-decanoic (capric), n-dodecanoic (lauric), n-tetradecanoic (myristic), n-hexadecanoic (palmitic), n-octadecanoic (stearic), n-octadec-9-enoic (oleic), n-octadec-9.12-dienoic (linoleic), n-octadec-9.12.15-trienoic (linolenic), n-docosanoic (behenic) and n-hexacosanoic (cerotic or cerotinic) acids. Crystalline ethane-1.2-dicarboxylic (succinic) acid was also isolated. Total ether-soluble acids isolated were found in beer at a concentration level of 125 p.p.m. compared with 67 p.p.m. for hopped wort and 61 p.p.m. for sweet wort. All volatile acids present in hopped wort were found to be present also In sweet wort, and in only slightly different proportions. Further, all volatile acids present in beer were found in hopped wort, though relative proportions differed.