The rolling boil

[dirtydingus]

Is there such a thing as to vigorous of a rolling boil? Yesterday I brewed a Rye. Pre boil volume, 9.38 gal. 90 min boil. When I racked to the fermenter there was barely 5.25 gal. Maybe my interpretation of a rolling boil isn't right. Thanx for any help.

 

[kombat]

I heat to an aggressive boil initially, then after the hot break dissipates I throttle it back to a gentle boil. You want enough agitation to drive off DMS, but it doesn't have to be violently frothing.

 

[porterpounder]

I read yesterday in a MBAA publication (http://www.mbaa.com/store/Pages/51919.aspx) that 8% is the ideal boil-off rate to allow for proper formation of break material and driving off unwanted compounds. It also said that most efficient commercial systems are set for a 5% boil-off.

 

[GilaMinumBeer]

Too vigorous a boil can have adverse effects on the intended beer. One, what little aroma/flavoring you'd get from bittering will be quickly driven off, you will very rapidly concentrate the wort, and finally a much higher rate of carmelization or maillard reactions will take place thus altering the intended mouthfeel and fermentability of the wort.

 

[dirtydingus]

I read yesterday in a MBAA publication (http://www.mbaa.com/store/Pages/51919.aspx) that 8% is the ideal boil-off rate to allow for proper formation of break material and driving off unwanted compounds. It also said that most efficient commercial systems are set for a 5% boil-off.

I will have to do some practicing with plain water. By my calculations, if I start with 8 gal water, 8% is 2.56 qts. Good responses from all. I have some experimenting to do. Thanx.

 

[stpug]

Percentages in boiloff rates are not helpful. Afterall, 10% of a preboil 5 gallon batch is half as much as 10% of a preboil 10 gallon batch, BUT their boiloff rates shouldn't differ by that much!

1 gallon per hour is a nice number, but you may go as little as 0.75 gal/hr or as high as 2.5 gal/hr.

 

[Chadwick]

My boils are not super aggressive. I think my boil-off rate is around 1-1.5 gallons per hour. I usually do 90 minute boils starting with about 8-8.5 gallons of wort. It varies some from beer to beer. My big giant barleywines sometimes start off a little over 8.5 gallons and end up being 5.5-6 gallons into the fermentation vessel. These boils are more aggressive. Lighter beers are boiled less aggressively. These usually start with less wort to begin with, so I'm not trying to reduce them as much either. When it is all said and done, I like for my boils to last at least 90 minutes. I like to know that I've driven off as much DMS as reasonably possible. It isn't uncommon for me to do a 90 minute boil and not even begin hop additions until the 60 minute mark.