“No chill” brewing

Q: I have been reading about a method of chilling called “no chill,” where the brewer simply pours the wort after flame out into a suitable water container, purges the air and seals it airtight.  What are your thoughts?
— Nick Rolheiser • Edmonton, Alberta

A: My first thought is that this method is certainly not new. Rapid chilling is a very recent development in the history of brewing. Prior to the advent of the plate heat exchanger, brewers had to wait for wort to cool prior to pitching. Most breweries eventually settled on coolships, which are large shallow pans resembling Olympic-sized kiddy pools, to cool wort prior to fermentation. Although cooling required only eight hours or so, wort contamination was a real issue with the coolship design.

Then, in 1856, Jean Louis Baudelot invented a novel wort chiller and the brewing world was changed forever when his invention made rapid chilling a reality. The Baudelot chiller was copied and later modified into enclosed designs. Baudelot’s basic design is still widely used in all sorts of different heating and cooling applications.

There are two real problems with slow wort chilling. One is the risk of microbiological contamination. The other problem associated with slow wort cooling is DMS formation after wort boiling. The precursor for DMS, S-methyl-methionine, decomposes when heated and becomes DMS (DMS smells like cooked corn and most brewers consider it a defect in almost all beer types). Although much of this compound is transformed to DMS and removed with steam vapor during wort boiling, some does remain. This means that the wort DMS concentration increases after boiling and prior to cooling, and is especially noticeable if wort is in a sealed container that prevents the volatile DMS to escape.

The good news is that homebrewers do not have a very large volume of wort to chill and it is certainly possible to cool a carboy of wort in a reasonable time frame if the carboy is plunged into a cold water bath that is kept cold during cooling. Agitating the carboy will also dramatically increase the heat transfer rate during cooling. My personal preference is to cool wort using a wort chiller either in the kettle with an immersion chiller or en route to the fermenter with a plate or shell-in-tube chiller. I suppose if I were brewing on a desert island and only had the no-chill method I would make do, but neither one of us is stranded on an island.