Determination of Beer Bitterness by UV Spec 1. In what region of the electromagn

ID: 552372 • Letter: D

Question

Determination of Beer Bitterness by UV Spec

1. In what region of the electromagnetic spectrum are the absorbance measurements being made?

2. Why is it essential that quartz cuvettes are used and not glass or plastic cuvettes?

3. As mentioned in the introduction, the bitterness of beer in IBU can be calculated.

Details (the formula) can be found at the following web site:

http://www.howtobrew.com/section1/chapter5-5.html

Another good website is: http://www.brewersfriend.com/ibu-calculator/

Calculate the bitterness in IBU for the following 5-gallon recipe:

• 6 lbs Light Malt Extract & 1 lb Dry Wheat Malt Extract (extract version)

• Batch Size, 5 Gallons

• 1 lb De Wolf-Cosyns Special B

• 3/4 lb. De Wolf-Cosyns Chocolate

• 1/4 lb. De Wolf-Cosyns Roasted Barley

• 1 oz Northern Brewer 8.6% Alpha Acids (boiled for 60 minutes)

• White Labs British Ale Yeast

4. Determine the bitterness of the following imperial stout in IBU’s. The Bitterness

Calculator will be useful: http://www.hotv.org/tools/hopinfo.html

Brewing Method: Partial Mash Boiling Time: 1 hour

Yeast: Wyeast 1056 Primary Fermentation: 7 days

Yeast Starter: 1 qt. Secondary Fermentation: 30 days (70 degrees F)

Batch Size: 6 gallons

Original Gravity: 1.105

Final Gravity: 1.028

Alcohol Content: 8.40 %

Grain Bill: Hop Bill:

14 pounds M & F LME 2 ounces Centennial Pellets 10.3 %(50 minutes)

1 # Dark Crystal Malt 1 ounce Czech Saaz Pellets 3.5 % (15 minutes)

1/2 # Munich malt

1/2 # Roasted Barley 1 ounce Willamette Pellets 4.0 %(2 minutes)

1/2 # choc. malt

1/4 # Black Patent Malt

1/2 # br. sugar

Bitterness Value from the Bitterness Calculator: _____________

1. the absorbance measurements range is generally 200 nm -800 nm.

2. because in the uv vis region quartz cell does not absorb light, where as glass and plastic absorb a smallamount of the light in the region.

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.