Aims: The objective of this study was to investigate what types of enzymes are being produced by non-Saccharomyces yeasts isolated from grapes in South Africa vineyards and clari®ed grape juice. These enzyme pro®les could pave the way for attributing speci®c effects in wine to some of these enzymes produced by so-called wild yeasts associated with grape must. Methods and Results: In this study 245 yeast isolates, belonging to the genera Kloeckera, Candida, Debaryomyces, Rhodotorula, Pichia, Zygosaccharomyces, Hanseniaspora and Kluyveromyces were screened for the production of extracellular pectinases, proteases b-glucanases, lichenases, b-glucosidases, cellulases, xylanases, amylases and sulphite reductase activity. These yeasts, representing 21 species, were previously isolated from grapes and clari®ed grape juice. The production of all extracellular hydrolytic enzymes screened for was observed except b-glucosidase activity. The amount and range of enzymes produced varied with different isolates of the same species. Conclusion: This study clearly revealed the potential of non-Saccharomyces wine yeasts to produce a wide range of useful extracellular enzymes during the initial phase of wine fermentation. Signi®cance and Impact of the Study: Enzymes produced by indigenous yeasts associated with grapes and juice might be harnessed to catalyse desired biotransformations during wine fermentation.

There is a growing consumer demand for wines containing lower levels of alcohol and chemical preservatives. The objectives of this study were to express the Aspergillus niger gene encoding a glucose oxidase (GOX; beta- d-glucose:oxygen oxidoreductase, EC 1.1.3.4) in Saccharomyces cerevisiae and to evaluate the transformants for lower alcohol production and inhibition of wine spoilage organisms, such as acetic acid bacteria and lactic acid bacteria, during fermentation. The A. niger structural glucose oxidase (gox) gene was cloned into an integration vector (YIp5) containing the yeast mating pheromone alpha-factor secretion signal (MFalpha1(S)) and the phosphoglycerate-kinase-1 gene promoter (PGK1(P)) and terminator (PGK1(T)). The PGK1(P)- MFalpha1(S)- gox- PGK1(T) cassette (designated GOX1) was introduced into a laboratory strain (Sigma1278) of S. cerevisiae. Yeast transformants were analysed for the production of biologically active glucose oxidase on selective agar plates and in liquid assays. The results indicated that the recombinant glucose oxidase was active and was produced beginning early in the exponential growth phase, leading to a stable level in the stationary phase. The yeast transformants also displayed antimicrobial activity in a plate assay against lactic acid bacteria and acetic acid bacteria. This might be explained by the fact that a final product of the GOX enzymatic reaction is hydrogen peroxide, a known antimicrobial agent. Microvinification with the laboratory yeast transformants resulted in wines containing 1.8-2.0% less alcohol. This was probably due to the production of d-glucono-delta-lactone and gluconic acid from glucose by GOX. These results pave the way for the development of wine yeast starter culture strains for the production of wine with reduced levels of chemical preservatives and alcohol.

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The powerful combination of analytical chemistry and chemometrics and its application to wine analysis provide a way to gain knowledge and insight into the inherent chemical composition of wine and to objectively distinguish between wines. Extensive research programs are focused on the chemical characterization of wine to establish industry benchmarks and authentication systems. The aim of this study was to investigate the volatile composition and mid-infrared spectroscopic profiles of South African young cultivar wines with chemometrics to identify compositional trends and to distinguish between the different cultivars. Data were generated by gas chromatography and FTMIR spectroscopy and investigated by using analysis of variance (ANOVA), principal component analysis (PCA), and linear discriminant analysis (LDA). Significant differences were found in the volatile composition of the cultivar wines, with marked similarities in the composition of Pinotage wines and white wines, specifically for 2-phenylethanol, butyric acid, ethyl acetate, isoamyl acetate, isoamyl alcohol, and isobutyric acid. Of the 26 compounds that were analyzed, 14 had odor activity values of >1. The volatile composition and FTMIR spectra both contributed to the differentiation between the cultivar wines. The best discrimination model between the white wines was based on FTMIR spectra (98.3% correct classification), whereas a combination of spectra and volatile compounds (86.8% correct classification) was best to discriminate between the red wine cultivars.

Relatively high numbers of suicides occur in the South African Police Services. The objective of this research was to determine the relationship between sense of coherence, generalised self-efficacy, locus of control and coping on the one hand and suicide ideation among police personnel on the other hand. The study population (N = 287) consisted of uniformed police personnel in the North West Province. The results showed that sense of coherence and generalised self-efficacy are related to suicide ideation of police members. A discriminant analysis showed that sense of coherence, coping strategies and medical status correctly classified 81,48% of participants who scored high on suicide ideation. Opsomming ‘n Relatiewe hoë getal selfmoorde kom in die Suid-Afrikaanse Polisiediens voor. Die doelstelling van hierdie navorsing was om die verband tussen koherensiesin, algemene selfdoeltreffendheid, lokus van beheer en coping enersyds en selfmoorddenkbeeldvorming van polisiepersoneel andersyds te bepaal. Die studiepopulasie (N = 287) het bestaan uit polisiepersoneel in die Noordwes-Provinsie. Die resultate het aangetoon dat koherensiesin en algemene selfdoeltreffendheid verband hou met selfmoorddenkbeeldvorming by polisieper-soneel. ‘n Diskriminantontleding het aangetoon dat koherensiesin, coping-strategieë en mediese toestand 81,48% van die deelnemers met hoë tellings ten opsigte van selfmoorddenkbeeldvorming korrek geklassifiseer het.