Too much air?

[Dugin]

I've recently started doing small, 1 gallon batches to try out brewing new styles without committing to a 5 gallon batch. I've done three so far (none out of the secondary phase) and all three have a slight sour smell and taste to them. The first was a Belgian Tripel. This was my first attempt at all-grain and also the first time I cultivated yeast from a commercial beer so I attributed the sour smell to a mistake somewhere along the way. I racked to a 1 gallon jug and am conditioning it at cellar temp. I made the next two batches using my usual partial mash. I sterilize like crazy so I'm pretty sure it's not a matter of contamination. The only common factor in these batches is that I'm fermenting in 6 gallon carboys then racking them to 1 gallon jugs for the secondary. Is the beer just getting too much air in the primary and becoming sour just like a beer left on the counter for a couple of days?

 

[LagerLover24]

If I understand correctly your fermenting 1 gallon in a 6 gallon carboy, leaving 5 gallons of head space. I think your definitely having oxygenation issues. Normally the fermentation would purge oxygen from the carboy before it could produce off flavors. But the beer is in contact with air much longer now, because it takes more time for the C02 to fill the carboy. Also, In my opinion a secondary fermentation does more harm than good. I was having similar off flavors in my ales. So now I just leave it in the primary until I bottle. It improved my beer quite a bit, maybe your having the same problem. Try fermenting in the one gallon jugs and leaving it.

 

[Dugin]

Do you think the one gallon jug will leave enough space to ferment in?

 

[LagerLover24]

I would try to leave a little head space, and use a blow off tube.