I’ve made a lambic every calendar year since 2013. The 2013 is in bottles now, and it’s a bit ropy and has some diacetyl, but otherwise isn’t bad. The 2014 is still in its glass fermenter, although curiously lacking a pelicle.
The 2015, however, was quite a sight to behold when I cracked the lid last week:
The smell wasn’t great, either. I had no doubt this was a dumper, but the forms of the infection were fascinating. The beige covering most of the surface of the liquid is feathery and powdery – much like you’d expect a Brettanomyces pelicle. It was the enormous green mats that concerned me. They were highly convoluted, and surprisingly hydrophobic. you can see water droplets from condensation barely clinging to the bacterial mats, and with any disturbance these drops rolled off into the brew. As I dumped the batch out, I had to handle the mats - they weren’t going down the drain! They were about ¼” thick and felt a lot like the half-hardened paint you might peel out of the bottom of a tray you forgot to wash: rubbery and resilient. If you look carefully, you can see that these mats were playing host to yet another bug: white fuzzies around the perimiter and hidden in some of the deeper folds.
This was brewed using the same recipe, but I had added two bottles of pasteurized tart cherry juice. The 2013 batch had, instead, fermented on 4lb of pitted cherries. This batch was also fermented in one of the fancy new BSG 6 gallon buckets, on which the lid doesn’t quite fit. So it’s quite possible the contamination came in on a dust particle or the belly of a fruit-fly.
Luckily there’s lots of 2015 left, so I still have plenty of time to brew a 2015 lambic!