Master Brewer Certification Brewer Quality Control & Testing 5

Question 1

Which microorganism is most commonly responsible for 'ropy' or 'sick' beer characterized by an unpleasant sliminess?

Accepted Answer

Pediococcus damnosus producing exopolysaccharides

Answer

Pediococcus damnosus produces beta-glucan exopolysaccharides that cause beer to become ropy or viscous — a spoilage condition called 'sick beer' that can recover with continued conditioning.

Question 2

When should a TTT (Time-Temperature-Turbidity) test be performed in the brewing process?

Accepted Answer

To evaluate chill-haze formation potential in finished beer at cold temperatures

Answer

The TTT test chills beer samples to near freezing and measures turbidity development over time, predicting the beer's susceptibility to chill haze in retail cold storage.

Question 3

What is the function of PVPP (Polyvinylpolypyrrolidone) in beer production?

Accepted Answer

Adsorbing polyphenols to improve colloidal stability and prevent haze

Answer

PVPP selectively adsorbs polyphenols (tannins) responsible for protein-polyphenol haze formation, improving colloidal stability and extending shelf life clarity.

Question 4

A master brewer is investigating high foam stability complaints in a finished lager. Which compound would most likely be contributing to excessive foam retention?

Accepted Answer

Lipid transfer proteins (LTP1) and glycoproteins from malt

Answer

LTP1 and other foam-positive proteins from malt form stable foam structures — while usually desirable, excessive levels from high-protein malt or certain conditions can create overly persistent foam.

Question 5

Which on-site rapid test kit is commonly used by brewers for detecting Lactobacillus and Pediococcus contamination in 24–48 hours?

Accepted Answer

Iso-sensitest broth with actidione and nalidixic acid (selective medium)

Answer

Selective broths containing actidione (cycloheximide to suppress yeast) and nalidixic acid (to suppress gram-negatives) allow rapid detection of lactic acid bacteria in brewery samples.

Master Brewer Certification Practice Test

Master Brewer Certification Practice Test

Master Brewer Certification Brewer Quality Control & Testing 5