Anyone out there who has made raspberry wine or blackberry wine from commercially grown fruit in the Pacific Northwest (BC, Washington, Oregon) may have encountered some sedimentation in their wines a few months after bottling. It has happened to me a few times and after doing all the stability tests, making sure the wine is as stable as can be, it is very disheartening to find this sedimentation forming in the bottles.
I have set out to understand what this problem which seemed to happen mostly with blackberry and to a lesser extent raspberry wine.
After sending samples to a commercial wine lab in California (Vinquiry) I finally got to the bottom of this problem. Ellagic acid was the culprit….
I would like to share some of the background information on this so that if you ever encounter this, you will not have to pull your hair out as much as I had to.
Ellagic Acid is a phenolic compound that has become known as a potent anti-carcinogenic compound. It also has antibacterial and anti-viral properties. Ellagic acid itself is not thought to be naturally present in plants. Instead, polymers of gallic acid and hexahydroxydipenoyl (HHDP) are linked to glucose centers to form the class of compounds known as ellagitannins. When two gallic acid groups become linked side-by-side within a tannin molecule and (sic)HHDP group is formed.
Ellagic acid is the result when the HHDP group is cleaved from the tannin molecule and spontaneously rearranges. It is the ellagitannins that are present in red raspberries. Some articles in which ellagitannins are quantified refer to ellagic acid because quantification of ellagitannins is done by breaking them down into ellagic acid subunits and quantifying the subunits.
The Meeker red raspberry is the best source of ellagic acid followed by Chilliwack and Willamette. As for the “Evergreen” blackberries, they have been found to have the highest levels of Ellagic acid of all other blackberry varieties, including wild ones.
Ellagic acid is actually very good for you health wise, just not that nice when it precipitates in the bottle. There is no real efficient way to get rid of it in the juice or wine prior to bottling but the technician told me of a trick to limit its formation.
This is technically illigal to do in commercial winemaking in California but is certainly allowed almost everywhere else in the world and for amateur winemakers alike. That is to add small amounts of citric acid to the wine prior to bottling. Small amounts like 0.2g/L would be sufficient to prevent the chemical reaction of ellagic sediment formation from occurring.
I must say that I have done that ever since learning about this and have not had this problem since.
It’s worth a try.
Happy fruit wine making!