Photocopy of typescript. / Digitized by Kansas State University Libraries

No description available.

No description available.

Thesis (MTech (Food Technology))--Cape Peninsula University of Technology, 2018. / Fungal diseases in vineyards are one of the main causes leading to economic losses within the viticultural sector and are continuously increasing over years. The most common of these fungal diseases are powdery mildew, downy mildew and grey mould. Commercial fungicides to treat the above-mentioned diseases are available and their usage is regulated under Act 36 of 1947 to comply with Good Agricultural Practises (GAP). However, the application of less-harmful, natural alternative fungicides to control vineyard diseases are currently an important research focus since the demand for organic products by consumers and retail companies are increasing. However, fungicide residues can alter the fermentation process and prevent some biochemical pathways of yeast metabolism involved in phenolic and/or aroma compound production that are critical for sensory quality. Therefore the aim of the study was to investigate the effect of fungicide treatments on the fermentation rate, yeast proteins expressed, aroma compounds released and sensory profile of wines produced. In the study, Chenin Blanc grapes treated with chemical and natural fungicides (1x treatment and 2x treatment) under Good Agricultural Practises (GAP) were used to produce small-scale wines and laboratory-scale fermentations. Laboratory-scale fermentations were conducted in duplicate using the commercial Saccharomyces cerevisiae (S. cerevisiae) Active Dry Wine Yeast (ADWY) strains VIN 13 and VIN 7. The fermentations were monitored by frequently weighing until they stabilised (CO2 weight loss). Small-scale wines were produced using the commercial S. cerevisiae ADWY strain VIN 13 only. Wines were made according to the standard Nietvoorbij experimental winemaking procedure. At the end of fermentation, lees samples were plated onto Yeast Extract Peptone Dextrose (YPD) agar and colonies grown were subjected to CHEF gel electrophoresis to confirm that the S. cerevisiae yeast strain inoculated at the beginning of the fermentation completed it. Moreover, fermenting wine samples, collected at the start (lag phase) and at end of fermentation (stationary phase), were subjected to protein extraction, quantification and characterisation in order to investigate fermenting wine yeast proteins. Furthermore, the final wines were subjected to chemical analyses as well as measurement of aroma enhancing metabolites (esters, higher alcohols, fatty acids and thiol compounds) using GC – FID and MS. Additionally, duplicate samples of the wines were evaluated sensorially by a trained panel of 12 winemakers and researchers, using an unstructured line scale. Wines were compared to the control wine according to visual (colour), flavour (tree fruit, tropical fruit, and wine foreign), taste (body mouthfeel, acidity) and overall quality. The data collected from the study was statistically analysed using a two-way analyses of variance (ANOVAs) and subject to a multiple factor analysis (MFA). From the results obtained in the above study, it was concluded that yeast strains used for winemaking completed the fermentations at a similar rate to their respective controls. In addition, small-scale cellar fermentations showed that fungicide treatments (1x treatment and 2x treatment) compared to the controls had no notable negative effects on wine aroma and sensory profiles although differences were observed in the proteins expressed after the fermentation. Overall, the fungicide treatments did not negatively affect the yeast performance, yeast protein expressed, aroma compounds released and sensory profiles of the wines produced. Further studies are recommended on other white as well as red wine grape cultivars to fully assess the effects of the fungicides.

Copies of author's previously published articles inserted. / Bibliography: leaves 184-197. / xxvi, 197 leaves, [5] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1995

Copies of author's previously published articles inserted. Bibliography: leaves 184-197.

Excessive growth by red clover, Trifolium pratense L., grown for seed interferes with maximum seed production and harvest in Oregon's Willamette Valley. This study was conducted during 1986 and 1987 on red clover cv. Kenland to determine if plant height and dry matter production could be inhibited and seed yields improved with the plant growth regulators (PGRs) uniconazol (XE-1019) and paclobutrazol (Parlay). The effects of different soil-applied and foliar-applied PGRs and application rates on plant height, crop biomass, and yield components of red clover were measured at Corvallis, OR on Woodburn silt-loam (fine-silty mixed mesic Aquultic Argixerolls) soil. Soil-applied PGRs were also managed under single and multiple irrigation regimes in 1986. Under a single irrigation regime in 1986, canopy height was reduced by 32% when XE-1019 was applied at 1.12 kg ai/ha and was reduced by 13% when Parlay was applied at 1.68 kg ai/ha. Averaged over the two-year period, straw yield was reduced 40% with XE-1019 (1.12 kg ai/ha) and by 12% with Parlay (1.68 kg ai/ha). Seed yield was increased by 11% with the lower XE-1019 rate (0.14 kg ai/ha) and was increased by 14% with the higher Parlay rate (1.68 kg ai/ha). Soil-applied PGR treatments reduced canopy height by 25% with XE-1019 (1.12 kg ai/ha) and was reduced by 11% with Parlay (1.68 kg ai/ha) under multiple irrigation in 1986. Straw yield was reduced by 30% with XE-1019 (0.84 kg ai/ha), but Parlay had no effect on straw yield. In addition, seed yield was increased by 8% with XE-1019 (0.56 kg ai/ha) and by 18% with Parlay (1.68 kg ai/ha). Foliar-applied XE-1019 (1.12 kg ai/ha) reduced canopy height by 13% in 1986 and by 25% in 1987, whereas foliar-applied Parlay (1.12 kg ai/ha) reduced canopy height by 9% in 1986 and by 19% in 1987. In 1986, seed yield increases averaged 16% across all 3CE-1019 treatments (0.07 to 1.12 kg ai/ha) and was increased an average of 21% across all Parlay treatments (0.28 to 1.68 kg ai/ha). However, 1987 was drier and warmer than 1986, consequently, foliar-applied XE-1019 reduced seed yields by an average of 23% and Parlay reduced seed yields by an average of 21%. Total dry weight and straw weight were unaffected by foliar-applied PGR treatment in both years. Use of XE-1019 and Parlay in field crop production has the potential to reduce dry matter production and improve seed recovery, but results vary from year to year. These PGRs have the potential to improve seed yields and may be effective in improving harvest conditions by reducing vegetative biomass. / Graduation date: 1995

No description available.

No description available.

No description available.