Sunday, March 25, 2012

Small Batch Brewing & Step Mashing

Small Batch Brewing:
I'm brewing up some "small" batches of beer now so that I can experiment with a wider range of styles with less cost and less beer to bottle and keep around. Yesterday was the first attempt at this; Liz and I brewed up two Belgian beers - a Witbier (white beer) and a Belgian Dark Strong. Both beers are ales and have the same fermentation profile which allows me to place them both in the fermenter and ferment at the same temps/schedule.

Witbier on the left, Dark Strong on the right.
It'd been a month or so since we last brewed since most of our free time was consumed with studying for the BJCP beer judge exam, so we made a couple minor mistakes along the way, but hopefully nothing that will drastically affect the finished beer.

When boiling smaller volumes of wort, the boil off rate increases significantly, which results in increased a higher Original Gravity and a lower volume of finished wort in the fermenter. Next time I'll need to raise my batch from 3 gallons to 3 1/2 and increase my brewhouse efficiency rate. The Witbier ended up with 90% brewhouse efficiency (I had figured 75%), but yielded just over 2 gallons.

Step Mashing:
We also step mashed yesterday for the first time. The Witbier has a high amount of wheat (35%) and oats 8% which would create a wort that is highly viscous and likely impossible to sparge. To avoid a potential stuck mash, we performed a protein rest at 130F for 15 minutes before raising the temperature to 150F.  I started the mash in a kettle by heating water to 145F and doughing in to hit my target of 127F (was high though at 130F). After letting it rest at that temp, I turned the heat on low and attempted to slowly raise the temperature to about 155F. I wanted to over heat slightly so when I transferred to the mash tun cooler, I'd hit 153. I ended up losing 5 degrees when I transferred so, I'll have to plan for that next time.

The problem that occurred is I didn't realize how fast the mash temperature could rise with such a small mash. I had the heat on low and was stirring constantly to avoid scorching the grains. After a few minutes, I checked the temperature and I had hit 170F! I quickly filled a pitcher of water with 120 degree water (from my tankless heater) and poured a half gallon in. That was enough to lower the temp down to 140. I then slowly raised it to 155F and then poured into the mash tun. I was concerned I may have stopped the alpha amylase enzyme activity but it was only at that temp for about 2 minutes. My efficiency was quite high, so I think I'm ok. It also didn't help that the Dark Strong was beginning to boil (and boil over) at the same time I was trying to raise the mash temp!

1 comment:

  1. You have to consider the volume of wort when calculating efficiency. A higher boil evaporation rate does not effect efficiency, because you have less wort.

    Think of it this way: if your system typically yields 4 gallons of 1.040 wort, but due to a higher evaporation rate you end up with 2 gallons of 1.080 wort, your efficiency is still the same. In both cases you ended up with 160 pts of sugars.

    Efficiency is just the ratio of the sugars you ended up with vs the maximum amount of sugars contained in the grain. It doesn't matter how dilute or concentrated they are.