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View Full Version : Loss of Volatile Compounds through Air Lock



ScotRob
09-01-2012, 04:19 PM
Apologies if this has been asked before (although I did search and could not find any clear answers): how does one stop volatile aromas/esters/compounds being lost through the air lock during fermentation? And is this something which one needs to worry about or is such a loss minimal anyway?

BBBF
09-01-2012, 05:53 PM
You can pick a less vigorous yeast and ferment at a cooler temperature.

fatbloke
09-02-2012, 03:16 AM
Pretty much what BBBF suggests.

You're always likely to lose some of the aromatics during primary, or at least early stages of primary, when the ferment is at it's most vigorous. Hence it's worth thinking about your choice of yeast and it's properties (which is why I changed from using stuff like Youngs, Ritchies, even most of the Gervin range etc, because they don't publish anywhere near as much data about their products - it's no hardship to mail order the Lalvin stuff to get the greatest amount of data for).

A good example, would be, if you read around the forums (here and others), people seem to fall for the sell by the HBS to use something like EC-1118 or other champagne yeast. These type are known to shift aromatics and some of the more volatile flavouring elements straight out the airlock. Whereas, I've found (some researching/digging, but also personal practice) that rather than EC-1118, you seem to get a better result with K1V-1116 (the Montpellier strain, which is also available as the harder to get Gervin Varietal E). It can be used for re-starts, straight ferments, etc, it will go to about 18% ABV, it's low nutrient requirement, low H2S producing (handy as it's less likely to stink if the brew/yeast gets stressed), etc etc.

The lalvin yeast chart is here (http://www.lallemandwine.us/products/yeast_chart.php), but don't forget, most of the yeasts listed are only available as commercial sized packs. Some of them are available, presumably repackaged, via Morewine (http://morewinemaking.com/search/103218///Lallemand_Lalvin_Yeasts), but of course, that's gonna mean mail order for most of us.

Also, the info on the Lalvin chart does allude to grape must, but the basics seem to hold true for meads.

The commonly available Lalvin types, tend to be EC-1118, 71B, K1V-1116, RC-212 and D47 (that's off the top of my head). All of them will make reasonable to good meads, yet there's a few caveats to remember, like RC-212 is mainly a red wine yeast and it's a nutrient hog that goes stinky quite quickly if not monitored carefully, or D47 makes good meads, but if you ferment it above 21C/70F, it's known to produce fusels that take a very long time, if ever, to age/mellow out.

Hence it's really up to you to have a dig round, work out what you want to make and which other materials you're likely to need and whether you can get them (easily) or not.....

p.s. and yes, I suspect it's possible, that if you have access to the appropriate types of laboratory glassware, that you could make an airlock so that the escaping CO2 passes through some vodka or other potable alcohol, and captures some, if not pretty much all, of the volatile aromatics/flavours, which could then, theoretically at least, be added back to a batch.....