I've done the no chill and the fast chill on similar batches and I don't notice any difference in the taste nor have any other no chill brewers mentioned any off flavors from doing it. I've even done the fast chill to below 170 and then no chill from there on down with no noticeable differences.
RM, this is long, but I think you'll appreciate where it ends up. Bear with me:
It's always tough to know whether it doesn't make a difference, or that some people simply can't perceive it.
As well, people may come to accept a taste as part of the flavor profile even though it is a flaw for the style. There's some evidence people may do that with oxidation, and I've seen it with some people and extract twang.
From Barth's "The Chemistry of Beer" p. 205:
"
Dimethyl sulfide (DMS, Fig. 11.10) can give a cooked vegetable flavor to beer. It has a flavor threshold of 50 micrograms per liter (50 ppb). Dimethyl sulfide is continuously produced in hot wort from a sulfur-containing amino acid called
S-methylmethionine (Fig. 11.11) from the malt. DMS can be present at objectionable levels if boiling is not vigorous enough, if condensed steam is allowed to return to the kettle, or if some of the wort stays hot for a long time after boiling stops. This is the reason that wort is chilled as quickly as possible after the boil."
The question of course is that presuming the boil has been "vigorous enough," how much more DMS will be produced as the wort cools from boiling to whatever point where DMS is no longer being produced....
In this section of the book it doesn't say at what temp DMS production ceases, though I've read elsewhere various temps, including 156 F and 176 F. If one could get the wort temp below, say, 150 F, and then let it naturally cool the rest of the way, presumably DMS is minimized or eliminated.
As well, it also depends on whether we can perceive what is produced, or not.
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Further: the precursor SMM is in the malt; makes me wonder if different malts have different amounts of this, and thus different production of DMS. I'll have to dig into that. Possible that some doing no-chill are using recipes/malts that naturally produce less of SMM, and thus less DMS, and so it isn't as important in those contexts.
I don't know the answer to that. So to the web I go, and I find
this on the MoreBeer site:
"Proteins and DMS. Protein levels also increase the potential for dimethyl sulphide (DMS) formation in beer. The precursor of DMS, S-methyl methionine (SMM), is formed through protein breakdown during malting (14,15). Much of the SMM is convetted to DMS through thermal decomposition during kilning and wort boiling. DMS formed during kilning and wort boiling is lost to the atmosphere. Pale malts generally have higher levels of SMM than do darker, highly kilned malts. When the length or vigor of boiling is inadequate to convett all residual SMM, DMS may continue to form as the wort cools. This DMS may persist into the beer. Although some DMS is desirable in lager beers, levels in excess of 50 ppb are thought to contribute a cooked or sweet corn flavor. Six-row malts contain higher levels of the DMS precursor SMM, presumably because of their higher protein content."
So....it would appear that, yes, the malt is an intervening variable. A darker malt bill will have less SMM and thus DMS produced than one using light malts.
Whether no-chill is a "process flaw" will thus depend on the grain bill. Possible two people using no-chill will produce different DMS levels because their malt bills are different.
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As I've often said on HBT, people get to decide how to brew, and to brew in a way that makes them happy, and there are many ways to get there. We get to choose....I like that.
So if no-chill makes someone happy, more power to them.
My personal brewing odyssey has been one of continuous quality improvement. Whenever I learn of a process element that is supposed to improve the quality of the beer, I try to adopt it. Some of that is simple and obvious, such as the source of one's water. Or controlling fermentation temp. Or keeping oxygen away from the beer following fermentation.
Since, apparently, DMS is produced while no-chill is ongoing until a certain temp is reached, it was part of my process improvements that I would continue to chill wort to minimize DMS production.
Since it's also apparently dependent on the malt bill....it would seem the most prudent course of action, if one wants to be sure to minimize DMS, is to chill below the critical temp as quickly as possible, regardless of the malt bill.
@eogaard can choose whatever approach he wants. Perhaps he'll try both approaches and decide for himself what works best given his situation and palate and grain bills.
YMMV.
