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Master Brewers Association of the Americas > BREWING RESOURCES > Ask the Brewmaster
December 30
Hop varieties for dry hopping

​Q:  I'm brewing a blonde ale, all grain. I used Crystal hops for the 40 min, 20 min, and the last 5 min boil. Should I continue using Crystal hops for dry hopping? Or should I use Cascade hops, or a mix of both?

A:  For dry hopping, any of the three options are acceptable depending on what aroma/flavor attributes you desire in the beer. Crystal will contribute a spicy, flowery, slightly citrus aroma. Cascade will contribute a flowery or citrus (grapefruit) aroma. Most brewers have found that using a blend of hop varieties for dry hopping offers more depth and complexity in addition to increased flexibility due to supply and availability issues.

November 26
Warming Calculations

Q: I'm looking at initiating a can conditioning program. We are planning on filling the beer cold (~32–34°F). I will need to warm it up from the filling temperature to 65–70°F in order to initiate conditioning fermentation in the can. I need to calculate how long it will take to warm it through a "warming tunnel" given the ΔT and the temperature of the water used to warm it (~125°F). The can volume is 16 oz., so how much residence time will be needed to get the beer into the desired temperature range?

Also, if we wanted to build a warming table—i.e., an accumulation table that could hold an inventory of cans that slowly move under a hot water shower—how do I calculate how big to make it if I am running at 45 cpm and need a residence time of X (from the calculation above) to warm the beer properly?

A: Why don't you consider putting in a beer warmer so beer is instantaneously warmed to 64–68°F? I recall one particular brewery that looked at a "warming tunnel" but didn't like how high the temperature of the water needed to be (125°F) or how difficult it was to control the beer temperature. It seemed that to get the interior core of the beer up to 65–70°F, the beer next to the can wall would get close to the temperature of the water, possibly harming or autolyzing the yeast. Their current beer warmer is programmed so that if the water temperature goes above 77°F, the beer flow stops and the unit goes into recirculation to avoid "cooking" the beer.

November 03
DMS breakdown during wort boiling

Q: What time is needed for DMS breakdown during wort boiling?

A: Dynamic low-pressure boiling uses a temperature range of 100–103°C for wort boiling. Necessary parameters of wort boiling, such as the stripping of dimethyl sulfide (DMS), can be widely influenced by a number of factors including the number of pressure build-up intervals, the intensity of the pressure, and the rate of alteration of the pressure (Δp/ΔT). With all these factors in mind, total evaporation can be reduced to 4–5%. In this case, boiling and DMS reduction can be done in 60 minutes.

August 25
Pectin build up problems

​Q:  Is pectin build-up a problem for kegs or bottle fillers used to package cider?

A:  Pectin is found in fruits where it is part of the cell wall material.  It is a complex polysaccaride and forms a jell. There is very little available data on how to deal with pectin build-up on filling equipment in packaged cider, however many cider makers will use a pectinase enzyme to break it down and eliminate it from being a problem.  For cider makers who do not treat the pectin with an enzyme and package unfiltered product pectin build up can be an issue in both kegs and fillers.  I asked Joe Dirkson (Ecolab) and Dana Johnson (Birko) to weigh in on this. Their consensus is to use a heavier caustic concnetration (up to 4%) with an oxidizer additive to help break up the pectin.  They both preferred a hydrogen peroxide additive.  The additive has a short life in the caustic and must be injected in small amounts at regular increments to be effective and to keep a concentration between 1000-5000 ppm.

August 12
Aging of whole hops

​Q:  In Volume I of the MBAA Practical Handbook for the Specialty Brewer, in the hops section, it was stated that freshly harvested hops should be aged for a minimum of 6-12 months before using.  This caught me by surprise.  I would have figured fresher the better.  Really?

A:  For some hops, particularly low alpha aroma varieties, the slow oxidation that occurs in baled whole hops kept at freezing storage temperatures (below 0 degrees C) over the course of several months will develop, improve and stabilize their flavors.  This is due to the oxidation of certain compounds called sesquiterpenes.  The oxidized sesquiterpenes develop complex flavors.  However over aging the hops can also produce a harsh bitter quality and cheesy aromas. Most brewers are using pelleted hops so any request for aging would have to be made to the supplier and specified because once pelleted and packed into nitrogen flushed bags, the oxidation process is almost completely shut down. 

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