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Showing posts from November, 2019

Using seaweed to protein stabilise white wines

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By Karien O'Kennedy

Research has previously shown that carrageenan, a naturally occurring polysaccharide extracted from red seaweeds, can protein stabilise white wines effectively. As carrageenan is a renewable substance, it poses a very attractive alternative to bentonite. There are many types of carrageenans commercially available and the aim of this study was to evaluate these different types for their efficacy in protein stabilising white wines during the different stages of the white wine making process. Their impact on wine chemical and sensory analyses were also evaluated.
PROJECT LAYOUT: Various commercial carrageenans were characterised for water- and wine-solubility using viscosity index measurements.They were then screened, using different dosages, for their heat stabilising properties in a Riverland (Australia) Chardonnay finished wine that served as an initial screening process.A change in turbidity before and after heat treatment of less than 2 NTU was considered a reco…

Red wine improves your gut feel

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By Karien O'Kennedy

Alcohol consumption of any kind can lead to various adverse health outcomes. However, over the past few years there have been numerous studies linking the moderate consumption of red wine to certain health benefits. Most of these benefits are attributed to the polyphenol content of red wine, which includes the highly popularised component, resveratrol. There have also been various studies linking gut microbiota to a person’s over all well-being. In this study researchers investigated the influence of various alcoholic beverages on the gut microbiota and the subsequent health outcomes in large population cohorts.
PROJECT LAYOUT: The study investigated the effect of beer, cider, red wine, white wine, spirits and the sum of all alcohols on the alpha-diversity (how many different species) of gut microbiota in 916 UK female individuals.Alcohol consumption was derived from food frequency questionnaires where individuals reported the type, quantity and frequency of consu…

Cultivar biological response to Eutypa lata

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By Lucinda Heyns

Different cultivars differ in their susceptibility to Eutypa lata. The aim of this study was to determine the underlying molecular response that lead to cultivar tolerance or susceptibility to E. lata infection.
PROJECT LAYOUT: The study was conducted over three years.Merlot, Cabernet Sauvignon (CS) and Ugni blanc were inoculated with E. lata.Physical symptoms were recorded and plant defence responses were monitored. This included monitoring the activation of pathogenesis-related (PR) genes, oxylipin and phenylpropanoid pathways and the accumulation of stilbenes. The latter analyses were carried out using the millicell system that enables the molecular dialogue between E. lata mycelium and grapevine leaves to take place without physical contact.Expression of genes involved in sugar transport and cleavage were also monitored.
RESULTS: Merlot was the most tolerant to E. lata infection. In this variety infection triggered the expression of a number of defence related gene…

Analysis of soil microbiome in Esca vineyards

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By Lucinda Heyns

In this study, researchers wanted to study the microbial community in the soil of an older, Esca infected vineyard. It is known that microbes can stimulate and modulate plant responses and that the ecosystem of above ground microbes in vineyards is linked to soil microbes.
PROJECT LAYOUT: A 20 year old vineyard was selected and the study was conducted over four seasons.Bacterial and fungal communities of the soil were investigated.Samples were taken from soil around vines that showed symptoms of Esca, while the other samples were taken from soils around asymptomatic vines.Meta barcoding was the technique used to identify the microbes.This was the first, comprehensive study of the soil microbiome in an Esca infected vineyard.
RESULTS: Results indicated no difference in the abundance of microbes between the samples.From soil samples surrounding Esca infected vines, Esca-related pathogens as well as grapevine trunk disease pathogens were more prolific compared to samples …