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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 …

Oregano essential oils prime plant immunity to fight downy mildew

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By Lucinda Heyns

In this study, researchers wanted to better understand how essential oils (EO) can help to protect grapevines against downy mildew. Essential oils (EO) are considered promising compounds for use in plant protection as studies have indicated their antibacterial, antiviral and antifungal properties on numerous crops. The challenge is that their efficiency is dependent on factors such as timing of application, application methods and interaction between the host, the pathogen and the essential oil (EO).
PROJECT LAYOUT: Researchers wanted to determine: Whether continuous fumigation of grapevines with EO can control downy mildew. Through fumigation, some of the challenges regarding direct application could be avoided. What mechanisms were triggered inside the plant and the pathogens when exposed to EO. Whether EO represses downy mildew oomycetes or primes plant resistance.A custom-built chamber was used. This chamber allowed for continuous fumigation of potted vines with d…

New frontiers in quantifying smoke taint in vineyards

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By Lucinda Heyns

The aim of this projects was to start development of a non-destructive, in field method to detect what the extent of smoke taint is in grapevine canopies, after exposure to smoke from fires.
PROJECT LAYOUT: Seven cultivars were exposed to smoke under controlled conditions in two sites over two seasons. Sauvignon Blanc, Pinot Gris, Chardonnay and Pinot Noir in a commercial vineyard in Adelaide Hills region was used and Shiraz, Cabernet Sauvignon and Merlot in a vineyard in Adelaide. In the first part, physiological measurements were taken inside the canopy to determine degree of smoke contamination after exposure to smoke: Stomatal conductance was measured and infrared thermal images were acquired. Using machine learning modelling based on pattern recognition, which is based on predictable changes in stomatal conductance patterns as determined from infrared thermal image analysis, a model was developed to detect the degree of smoke contamination in canopies.
In the seco…

The effect of music on wine tasting

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By Karien O'Kennedy

Italian researchers did a study on the effect of music on the taste of wine. The motivation for such a study is valid since it is well documented and researched that taste can be a multi-sensory phenomenon. However, how these scientists went about researching this phenomenon is rather entertaining.
Disclaimer: This article is an opinion piece and the opinions expressed in this article are my own (Karien O’Kennedy) and may or may not represent the general opinions of Winetech.
EXPERIMENTAL LAYOUT Eleven women and 19 men with a mean age of 29.8 years were used as tasters of two different wines while two different types of music (or no music) played.These participants were unaware of the purpose of the experiment.The one wine was a Chardonnay and the second wine was a homemade Merlot (made apparently by using a crusher).The wines were served to the participants in plastic cups (Eish!)BOTH white and red wine (40 ml per tasting) was served at 5°C. Three music variable…