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Keeving and methanol

Posted: Sat Jan 16, 2021 5:03 am
by NormandieStill
So... I read the article on limiting methanol in eau-de-vie and the take home message is that the amount of methanol in the finished product is directly related to the amount in the wash (which makes sense) and that in the case of pears, limiting the amounts in the wash is difficult. High pectin fruits will produce high amounts of methanol due to the chemistry involved and that rapid fermentation and avoiding pectinase will have some effect.

I don't know how many traditional cider makers there are here (Jimbo and cranky seem to be candidates) but the traditional french method of producing cidre bouché relies on keeving before fermentation proper begins. This is used to starve the yeast of nutrients and allows you to produce sweet, naturally sparkling cider without pasturisation. It works by allowing / encouraging the pectin to form a cap on top of the juice which traps nutrients outof the juice. The juice is then drawn from the middle of barrel (between the brown cap and the lees) and subsequently fermented normally.

It occurs to me that since this method removes the pectin from the juice, it might have an effect on methanol levels. a keeving kit is available from a supplier in the UK which provides the chemical environment to encourage the formation of the brown cap. And while I've yet to test it, could in theory work with any high pectin fruit (I intend to test it on peaches in the future). Has anyone come across this, or should I be contacting the research team from the original paper to see if they could further the knowledge?