Lesson 5 - Wort and Beer Analysis SAQ
This lesson enables you to test yourself on the material covered in the Beer and Wort Analysis lesson, and determine the level to which you have met the learning outcomes.
Suggested Response - Q1
*The MEBAK method for calculating the calorific content of beer uses the amount of protein, carbohydrate, and alcohol in beer.
a) Other than Kjeldahl for protein and distillation for alcohol, what analyses could you use to measure each of these components?*
b) What is the calorific content (kJ) of a beer with 0.48 g/L TN, 3.7 g/100 mL carbohydrate, and 4.2 g/100 mL alcohol?
Response:
a) Dumas combustion can be used to measure total nitrogen which can then be multiplied by 6.25 to give an estimate of protein. For carbohydrate you mix the beer with sulphuric acid and then dye the solution with anthrone. This produces a blue-green colour in the solution. The absorbance of the solution is then measured at 625 nm in a spectrophotometer. With alcohol there is the option of using SCABA, NIR with a densitometer, or gas chromatography with a flame ionisation detector.
b) Energy (kJ/100 mL) = 17 x carbohydrate weight + 17 x proteins weight + 29 x alcohol weight
Protein = 6.25 x TN
6.25 x 0.48 = 3 g/L
Protein in 100 mL of beer = 3 / 1000 x 100 = 0.3 g
Energy = (17 x 3.7) + (17 x 0.3) + (29 x 4.2)
Energy = 62.9 + 5.1 + 121.8 = 189.8 kJ/100 mL