It's not every day that a household name in brewing is in town, but Sunday May 10th was one of those days. Chris White, the main man behind White Labs Yeast, was in Ireland for a few days and myself and a few others from Beer Ireland (of which I'm delighted to serve as Treasurer) managed to catch up with him in Dublin for a couple of hours to chat yeast and bacteria.
|Images used courtesy of White Labs|
The meeting lasted over two hours, so there is far too much to go into. Some of it was quite technical as well:- who knew that haploid yeast cells mate? I always assumed yeast cells were diploid and cloned themselves. That I learned from a question that came from Mark Nixon, head brewer at Trouble Brewing.
An interesting conversation evolved around a question I had prepared (I had about 30 prepared, mostly bacteria related) about kettle souring and the payment of excise duty. Lactobacillus does not necessarily convert its main food source, glucose, into any alcohol at all, so gravity readings in the conventional sense are meaningless. Chris confirmed the only way to confirm the ABV is to get your brew analysed. That or just over-pay your excise duty. Of course Mark was right that if you boil after souring for long enough you are also boiling off ethanol, further complicating the situation. But how long does it take to boil off all the ethanol present? I would think it would take as long as it would to boil off all the water too though, as alcohol and water are completely miscible. [My US readers may not be aware that it is common in Europe for brewers to have to pay an extra tax (excise duty) on beer based on ABV. The higher the ABV the more excise duty is due.]
Probably the most important advice though was that every brewery should have its own yeast lab, along with a couple of essential pieces of equipment. A DO meter is top of the list, and not one that is designed for water, but one for beer. The other is a microscope and any in the €400 to €500 range should do as long as it does 1000x under oil (White Labs sell such microscopes as it happens). I mentioned it to him that I have a microscope, but the possession is no indication of proficiency! He gave me a couple of simple tips: saccharomyces cells are circular, brettanomyces are "football" shape (i.e. American football, aka oval), and due to the vast size difference yeast and bacteria are not clearly visible under the same objective lens: use 400x for yeast, and 1000x for bacteria. I really must dig out the microscope again and start making proper use of it.
Pitching rates in double brewed batches came up too, the advice being that there is no need to pitch a second time if the second batch is brewed the day after the first, i.e. if fermentation is well under way. Relevant to me, as I'm tank shopping at the moment, is the advice to buy fermenation tanks that are three times the size of the brewhouse, as triple batching is now becoming common in the US. And conditioning tanks double the size of the fermenters. No prizes for guessing where that advice is coming from!
Anyone brewing long enough will know that Chris and Jamil Zainasheff have co-authored the brilliant book Yeast: The Practical Guide to Beer Fermentation (Brewing Elements) which is an invaluable reference for any brewer. I brought my copy along, and while I felt a bit cheesey in asking, Chris was quite happy to autograph it. He jokingly said that he left space for Jamil to autograph it too. I told him when he does it's going straight on ebay!
All in a great couple of hours and a huge thanks for Chis, who is not only an authority but a really nice guy too.