Is that rancid peanut butter in my wine?
No, it’s ladybird taint.
But ladybirds are so cute. How can they taste so bad?
These cheeky things love a damaged grape to feed upon and with cool climates getting warmer, these pests are moving into regions previously too cool for them. Kevin Ker of Brock University told the International Cool Climate Symposium, “It’s a hitch hiker that we really don’t like but it will find a way to spread.”
It has been found in the US, Argentina, the UK, Czech Republic, Italy and Denmark, and it is thought it is more widespread but no-one’s owning up.
When the ladybirds inadvertently get harvested along with the grapes they emit a methoxypyrazine that smells of rancid peanut butter or bell pepper. Not something you’d want in your glass.
What’s worse, it’s pretty potent – as little as 1200 beetles per tonne can taint the batch. The sensory threshold is just 1 part per trillion.
“One the wine has been made, cleaning up the wine is virtually impossible,” said Ker.
So what to do about these pesky ladybirds?
Brock University researchers have discovered that potassium metabisulphite, which is used as an antioxidant in the winery has been found to be relatively successful.
Ker added, “If used pre-harvest, the wines made from vines treated with potassium metabisulphite seemed to be fairly successful. It can be used pre harvest to reduce the number of lady beetles below the sensory threshhold levels.”
However, anything that’s added to the grapes so close to harvest could be an issue.
