Lab 10 update 1

Clarifying our brew

Purpose

During the same laboratory exercise on November 14, 2012, during which we started growing pearl oyster and Shitake mushrooms from purchased kits (see Lab 12 blog), we clarified the American amber ale we began brewing on October 31 (see Lab 10 blog).

Materials and methods

Carboy
Siphon
Hydrometer 
100-ml graduated cylinder
Acid sanitizer
70% ethanol
Tap water
Disposable lab gloves
Autoclave tubs
Laboratory sink
Rolling cart 

Results

The yeast (Saccharomyces cerevisiae) that we added 14 days ago to the wort (our brew) is finished eating the sugar (dry and liquid malt extracts), expelling proteins (the layer of junk at the bottom of the carboy) and fermenting the mixture into alcohol. We now need to clarify our brew. Laboratory co-instructor Dr. Brian Shaw is pictured with the unclarified brew.

Dr. Shaw gave instructions on sanitizing the siphon and carboy used to transfer and clarify the brew. We do not want bacteria and other microbes to get in our brew when we are in the home stretch to enjoying the fruit of our labor.

The acid sanitizer used to sterilize the siphon and carboy. You want to wear gloves to protect your skin.

Wenwei (pictured) sanitized the carboy. Xin had sanitized the siphon. Both used tap water to rinse the equipment. The sanitizer can generate a lot of bubbles, so 70% ethanol was used to break the surface tension and help rinse the carboy.

Many of us had eaten the octopus/coral form of pearl oyster mushroom found in the corners of our mushroom growing kit (see Lab 12 blog), so to avoid possible contamination (fungal spores in our mouths), Dr. Shaw (pictured) did the honors in getting the siphon started. He has done this many times before, so he is a pro at it anyway. Pictured looking on in the background are Chris (left) and Sheila).

Siphoning of the brew to a new carboy is nearly complete. We have it sitting in an autoclave tub so we do not mess up the floor. See how much better the brew looks without all the waste products from fermentation? Many of us wondered how it tasted. ...

But first Shan (left) and our other laboratory instructor, Dr. Dan Ebbole, tested the specific gravity (using a graduated cylinder and hydrometer), which can be used to calculate the percentage of alcohol by weight and volume (see calculations below). Notice the cup in Dr. Ebbole's hand. He can't wait to take a taste either. :-)

Pei-Cheng (pictured), Wenwei, Dr. Ebbole, Dr. Shaw and I were among those who tasted our clarified brew. It was good. Nice and smooth and not as bitter as the day we first made it. There is no grimace on Pei-Cheng's face. :-)

The original carboy after siphoning. Yuck!

 

O.G. = 1.052
F.G. = 1.014
Alcohol by weight (a.b.w.) = (O.G. - F.G.) x 105 = 3.99%
Alcohol by volume (a.b.v.) =  3.99 x 1.25 = 4.99% or 5%

Discussion

The beer will sit undisturbed in the new carboy for another week to mature in flavor and to continue to settle out. The beer will then be bottled during the laboratory exercise on November 21 (see Lab 10 update 2).