How does chilling my wort slowly affect the taste of my beer?

When I started brewing I used a plate chiller to chill my wort. I didn't like the process, and now I add cold water after the whirlpool and to get the wort down the last 10°C I put into my fermentation chamber with temp control.

I am aware of the infection risk, and am still wondering if this style of cooling will influence the taste of my beer. I don't recognize any off flavors.

Edit: I design the recipe with the addition of the water that I add after the whirlpool. BrewSmith calculates the changes in IBU, final gravity and so on.

Topic no-chill chilling flavor homebrew

Category Mac


Usually the biggest concerns of a slow chill are....

DMS (cooked corn flavor) is created from SMM when wort is hot. DMS will form until below 140°F (60°C). SMM is boiled off during boil, it's why we do an open lid boil. SMM has a half life of 37 minutes. 90minute boils usually reduce SMM levels below the perception threshold.

Unwanted bittering late addition hops (less than 45min) continue to isomerize until wort drops below 175°F (79°C)

Infection bacteria love warm temps. Below 160°F (71°C) (pasteurization temp) the wort is at risk of infection.

As far as adding cold water to chill, this could be very effective at dropping the wort below those critical temps very fast. But I would make sure the water is sanitary or sterile (pre boiled, chilled, sealed)

As far as the last 10°F(~5°C) allowed to slow chill. It's a common practice with few side effects other than risk of bacteria taking hold before yeast gets going. It may in some cases delay your pitch and add to the overall brew to glass time.

Update: forgot this initially.

Chill Haze when wort cools slowly this allows certain proteins to remain suspended resulting in chill haze. The thermal shock of a rapid chill of the wort causes them to drop out. Usually have to drop below 80°F (27°C) within 15 minutes for sufficient thermal shock. Chill haze is identified in finished beer by being hazy when cold but then gets clear when it warms up.


Try No Chill brewing where you don't worry about chilling the wort. https://beerandbrewing.com/no-chill-brewing/


I can think of a few possible things that might differ (assuming your recipe takes the cold water addition into account):

  • You've already mentioned the sterilising effect of boiling.

  • Boil volume can have an effect on hop isomerisation - the lower the volume, the lower the IBU.

  • pH has an effect on hop isomerisation.

  • A change in cooling rate will also affect hop isomerisation, though this is a commonly consideed variable anyway.

(See https://www.sciencedirect.com/science/article/pii/S0308814610006643 for some info on these effects).

  • Boiling water also boils off chloramine, which can give off flavours in the final beer (if using mains water which has been treated with it).

  • Caramelisation and maillard reactions may be affected by concentration.

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