Articles
ASSESSING THE RISK OF PHYLLOXERA SURVIVAL DURING WHITE GRAPE PROCESSING
Article number
1045_7
Pages
49 – 58
Language
English
Abstract
Dispersive stages of grape phylloxera, particularly first instars, can be inadvertently transferred on several potential vectors including post-harvest grape products such as juice.
Fermentation of red grape juice for at least 72 h will kill phylloxera or filtering will prevent first instar transfer.
White juice is processed differently to red juice, has different physiochemical properties and undergoes a range of treatments prior to filtering.
Tartaric acid may be added to ensure pH is within a range of 3.0-3.4. At various stages in the white wine-making process sulphur dioxide is generally added, as either potassium or sodium metabisulphite.
At maturity Baumé is usually between 10 and 12.5° depending on variety.
Cool temperatures are generally used for white grapes with fermentation occurring at 10-16°C or lower, clarification occurring below 15°C and cold stabilization occurring at -4 to +2°C. The impact of pH, Baumé, white juice, sulphur dioxide and cold temperature on first instar phylloxera mortality was tested and results are described.
In the absence of a food source first instar grape phylloxera survived up to 21 days in some treatments, including water at low temperature, which could also pose a quarantine risk.
Fermentation of red grape juice for at least 72 h will kill phylloxera or filtering will prevent first instar transfer.
White juice is processed differently to red juice, has different physiochemical properties and undergoes a range of treatments prior to filtering.
Tartaric acid may be added to ensure pH is within a range of 3.0-3.4. At various stages in the white wine-making process sulphur dioxide is generally added, as either potassium or sodium metabisulphite.
At maturity Baumé is usually between 10 and 12.5° depending on variety.
Cool temperatures are generally used for white grapes with fermentation occurring at 10-16°C or lower, clarification occurring below 15°C and cold stabilization occurring at -4 to +2°C. The impact of pH, Baumé, white juice, sulphur dioxide and cold temperature on first instar phylloxera mortality was tested and results are described.
In the absence of a food source first instar grape phylloxera survived up to 21 days in some treatments, including water at low temperature, which could also pose a quarantine risk.
Publication
Authors
K.S. Powell, R.J. Bruce , G.A. Korosi
Keywords
phylloxera, quarantine, white juice, sulphur dioxide, cold temperature, Baumé, acidity
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