German-style hefeweizen is one of my favorite styles of beer, and is a beer type that I feel pretty darn comfortable brewing, with two Great American Beer Festival medals in 2006 (gold) and 2008 (bronze) to boot. I tend to avoid style and recipe questions for this column, but this great style is one that many brewers seem to struggle with brewing. I am hoping that my tips help you.
The first bit of advice I have to offer is to keep recipes simple. Most hefeweizens have a grist bill that are about 40–50% malted barley and 50–60% malted wheat. I like adding about 2% dark crystal malt for a little color and just a small kiss of crystal sweetness. I am a fan of reverse osmosis (RO) water and target 100 ppm calcium in the brewing water from a blend of calcium chloride and gypsum. German hops are my go-to for this style and I like using two additions during the boil and a very small addition at flame-out for just a hint of hop nose. Bitterness is low at 12–15 IBU.
I do not believe there are any tricks or secrets to brewing a good hefeweizen, but there are a couple of techniques that I feel are very important. And the most important technique to me occurs at the very beginning of the brew day with a mash rest around 113–126 °F (45–52 °C). This temperature range allows for cytase activity and an increase in ferulic acid levels in the wort. Weizen yeast are so-called POF+ (phenolic off-flavor positive) because they have an enzyme system that converts ferulic acid to 4-vinyl-guaiacol during fermentation, imparting a clove-like aroma to the beer. My favorite weizens have a nice balance of clove and banana and this low temperature mash rest is a great way to ensure a nice punch of clove. Rests at 140 °F (60 °C) and 158 °F (70 °C) follow, with mash-out at 168 °F (76 °C) before starting wort collection.
The next critical step is preparing for fermentation. I have never tried starving weizen wort of oxygen or pitching at a very low rate, and have had success using typical aeration levels and pitching rates. I am picky about yeast strain selection and strongly suggest changing strains if you are not getting the aroma profile you like from Wyeast 3068; this is one of many nice weizen beer strains, and is definitely not the common factor of all great weizens. Since I like a nice clove profile in my weizen, strains that lean a little more towards the phenolic end of the spectrum are more my speed than the big banana bombers. A great way to select a strain is to brew a batch and split it 4–5 ways so you can trial 4–5 yeast strains. Find the yeast strain that is going to give you the aromas that ring your bell.
I suggest fermenting in the 64–70 °F (18–20 °C) range, allowing for a couple days for a diacetyl rest and cold crashing before bottling or kegging. Most weizen strains are true top-croppers, meaning that the yeast rises to the top of the fermenter where it can either be skimmed for re-use or the beer can be racked from beneath the yeast before cold crashing; the yeast that ends up on the bottom of the fermenter can then be collected and reused. Weizen yeast that is harvested in this manner can be used for many generations as long as it is not stored long between brews. Although carbonation level for this style is not likely to move the needle for thin, blah brews, tasty weizens certainly benefit from above average carbonation levels and proper weizen glassware. Prost!