Acetaldehyde metabolism by wine lactic acid bacteria and its oenological implications : a thesis presented in fulfillment of the requirements for the degree of Master of Science in Microbiology at Massey University

Acetaldehyde is one of the most important sensory carbonyl compounds formed during vinification. Excess acetaldehyde can adversely affect the flavour of wine and acetaldehyde plays a role in the colour development of red wines. Excess acetaldehyde is usually masked by the addition of sulphur dioxide (SO2) to the wine (SO2 is also used as an antimicrobial and antioxidant agent in wine and acetaldehyde bound SO2 is less effective in these roles). To date there has been no definitive study of the impact of wine LAB on free and bound acetaldehyde. Therefore, this study investigated the metabolism of free and bound acetaldehyde and its oenological implications. A survey of 11 commercial malolactic starter cultures (mostly Oenococcus oeni strains) showed that 9 out of 11 were able to metabolise acetaldehyde (in a resting state) with the corresponding formation of ethanol and acetic acid as products. SO2 bound acetaldehyde was also metabolised by the two strains tested (Lactobacillus buchneri CUC-3 and Oenococcus oeni MCW). This is the first evidence that LAB can indeed catabolise SO2 bound acetaldehyde, therefore releasing free SO2. During growth Oenococcus oeni EQ54 and Oenococcus oeni VFO were able to metabolise free acetaldehyde in wine at pH 3.3 and pH 3.6. In wine containing SO2 bound acetaldehyde, Oenococcus oeni EQ54 and Oenococcus oeni VFO were able to metabolise SO2 bound acetaldehyde at pH 3.6 after a period of sluggish growth. At pH 3.3 there was no metabolism of SO2 bound acetaldehyde by Oenococcus oeni EQ54 and Oenococcus oeni VFO during the incubation period. Results from growth experiments showed that in broth there was inhibition of growth at 300 mg/L concentration of acetaldehyde for all strains. In wine, no significant inhibition or stimulation of the cultures examined was found at any acetaldehyde concentrations up to 300 mg/L. In a simultaneous resting cell incubation of Saccharomyces bayanus Première Cuvée and Oenococcus oeni Lol11, acetaldehyde produced by the yeast was metabolised by the wine LAB. The metabolism of acetaldehyde by wine LAB is expected to influence wine flavour as small amounts of ethanol and acetic acid are produced and acetaldehyde is removed. This removal of acetaldehyde by wine LAB suggests that less SO2 will need to be added to the wine to mask excess acetaldehyde when malolactic fermentation is performed. Inhibition of wine LAB growth in broth by high levels of acetaldehyde suggests a role for acetaldehyde in stuck or sluggish MLF. Sluggish growth in wine containing SO2 bound acetaldehyde also suggests a possible role of SO2 bound acetaldehyde in stuck and sluggish MLF. This is due to the release of free SO2 through the metabolism of the acetaldehyde moiety of SO2 bound acetaldehyde

A study of semiconductor-based atomic oxygen sensors for ground and satellite applications

Available from British Library Document Supply Centre-DSC:DXN032263 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Chromo-Rayleigh Interactions of Dark Matter

For a wide range of models, dark matter can interact with QCD gluons via chromo-Rayleigh interactions. We point out that the Large Hadron Collider (LHC), as a gluon machine, provides a superb probe of such interactions. In this paper, we introduce simplified models to UV-complete two effective dark matter chromo-Rayleigh interactions and identify the corresponding collider signatures, including four jets or a pair of di-jet resonances plus missing transverse energy. After performing collider studies for both the 8 TeV and 14 TeV LHC, we find that the LHC can be more sensitive to dark matter chromo-Rayleigh interactions than direct detection experiments and thus provides the best opportunity for future discovery of this class of models.Comment: 21 pages, 9 figure

Management by Objectives: The Process and Status of Implementation in State Departments of Education and Selected School Districts

Purpose. The problem of this study was: (1) to determine which of the fifty state departments of education in the United States were participating in a Management by Objectives (MBG) system of management; (2) to determine which of the public school districts identified by their respective state departments of education were utilizing an MBO system of management; (3) to determine how such a system was installed in each agency; and (4) to determine if the concepts and techniques of MBO, as practiced in selected educational agencies, favorably compared to the standards established for this study. Method. The descriptive-survey method of research investigation wsb utilized to collect data from the managerial offices of the fifty state departments of education and selected school districts throughout the United States. Data were gathered using a two-part questionnaire which was completed and returned by selected educational administrators at state and local levels who had Implemented MBO in their educational agencies. Summary. MBO had been implemented in a majority of the state departments of education in the United States. Officials from state departments of education and various MBO consultants assisted in locating ninety-nine school districts that were involved with an MBO system. Officials from state departments of education and selected school districts provided responses relative to demographic data and information relative to the methods of MBO implementation (Part I of the questionnaire)and responses pertaining to MBO concepts and techniques (Fart II of the questionnaire). Data from the questionnaire were reported, and a narrative was written describing the findings. Conclusions. Twelve hypotheses, which were related to questions in Part I and Fart II of the questionnaire, were tested. Significant differences were found by testing the hypotheses using the Student\u27s t test. There were significant differences in mean scores relating to seven of the twelve hypotheses

Great Britain and the Evolution of the Western Part of the International Boundary of Canada

Abstract Not Provided

For Union, for Confederacy, for slavery : motivation for enlisting & serving among Kentucky\u27s Civil War soldiers.

Beginning with Bell Irvin Wiley\u27s 1943 The Life of Johnny Reb: The Common Soldier of the Confederacy, historians have produced many works describing the motivations for soldiers to enlist and serve during the Civil War. However, because they often set up an artificial North-South divide, while suggesting the North and South were homogenous units, the motivations of border state soldiers are not well represented in these works. This thesis starts to mend this oversight and it explores the motivations of white Kentuckians to join both sides of the conflict and remain at arms. This thesis also argues that slavery played a pivotal role in soldier motivations for both Union and Confederate Kentucky soldiers, a point not well developed by the few previous works on Kentucky Civil War soldiers