Showing posts from July, 2017

The effect of filtration on red wine

By Karien O'Kennedy
The aim of this study was to explore the impact of commercial scale filtration on wine macromolecules, colloids and sensory profile.

Project layout •Samples from commercial Shiraz and Cabernet Sauvignon wines from two bottling lines were collected before and after cross-flow filtration, before and after lenticular filtration, after 0.65 µm and 0.45 µm membranes. •Impact of membrane type was also assessed in one wine. •Wines were analysed at bottling and after nine and 18 months.
Results •No significant impact on tannin concentration, composition or colour probably as a result of the fact that these commercial filter membranes are not new and high tannin and colour cultivars were used; •Cross-flow and lenticular filtration had a minor effect on polysaccharides. 0.45 µm had the greatest effect; •Cross-flow filtration reduced average particle size the most; •After 18 months of bottling ageing the average particle size of filtered and unfiltered wines were the same for the…

Mixed fermentations to reduce ethanol content in wine

The aim of this project was to investigate the possibility of doing co-inoculation or sequential inoculation with Starmerella bacillaris (Candida zemplinina) and Saccharomyces cerevisiae in order to achieve lower alcohol wines.
Project layout •Three S. bacillaris strains and two S. cerevisiae strains were used in the study. •Fermentations were carried out in Barbera must; •Pure fermentations (each strain on its own) as well as five inoculation strategies were carried out: co-inoculation of the two species and 7, 24, 41 and 48h after S. bacillaris inoculation; •The best performing (in terms of alcohol reduction) couple and inoculation strategy were evaluated in 200 L must – 250.4 g/l sugar.
Results •In pure fermentations S. bacillaris did not ferment to dryness (in 233.2 g/l Barbera must) and produced up to 12% alcohol, with only residual glucose – confirming its fructophilic nature; •S. bacillaris produced slightly higher glycerol than S. cerevisiae and used slightly more sugar to produce 1% …

The epidemiology and etiology of fungi associated with Esca disease of grapevine

Esca is a grapevine disease believed to be caused by a complex of fungal pathogens. The aim of this project was to identify the Basidiomycete fungi associated with Esca disease in local vineyards and to study their biology.
The project was designed to achieve the following milestones:•Identification of fungi isolated from infected vines across different regions;
•Morphological classification of fungi associated with Esca;
•Taxonomic descriptions of new species;
•Pathogenicity trials;
•Spore trapping studies;
•Development of a PCR detection system.
Results:Internal and external symptoms associated with Esca have been characterised;The fungi associated with each symptom type have been identified;Spore trapping studies revealed that spores are released from fruiting bodies at large numbers from the end of May until the end of September which coincides with our traditional pruning periods. Susceptible wounds could therefore be prone to infection if not treated properly.Significance of the study…

Influence of compost addition on soil properties, root growth and vine performance

Source:BerndtF at the German language Wikipedia
The aim of this project was to investigate the effect of compost application on soil fertility, above and below ground vine growth, yield and grape quality in a commercial vineyard in Italy. Two different types of compost (compost from vine pruning waste and from cattle manure) was applied in two ways (inter-row and under-vine) in a mature Cabernet Sauvignon block over five years.
Results Long term addition of compost to a vineyard could be beneficial to soil properties, including organic matter and microbial biomass;Compost from vine pruning waste had the strongest stimulative effect on root growth, especially when applied under-vine. Compost from cattle manure did not significantly affect root growth.Application of cattle manure compost, inter-row stimulated the most vegetative growth;Over five years, under-vine application of pruning waste compost increased vegetative  growth while inter-row applicati…