Wort Boiling Theory SAQ

Question 1

Are enzymes denatured below boiling temperatures?

Answer 1

True. Most malt enzymes are denatured at mashing off temperatures (76-78°C), but some commercial enzymes are more heat stable.

Question 2

Does boiling destroy all microorganisms in wort?

Answer 2

False. Boiling destroys all vegetative bacterial and fungal cells, but some spores may survive.

Question 3

What is the recommended percentage of wort volume to evaporate during boiling?

Answer 3

About 4% is a good target for evaporation during boiling.

Question 4

Are reactions involving amino acids and reducing sugars the only source of flavour during the boil?

Answer 4

False. Hops and adjuncts also contribute to flavour during the boil.

Question 5

Can DMS form after wort boiling is complete?

Answer 5

True. DMS can form after boiling during wort clarification.

Question 6

What is the optimum pH at the end of wort boiling?

Answer 6

5.0-5.3.

Question 7

Why is ensuring the correct pH during the boil important?

Answer 7

• Improves protein coagulation
• Improves diacetyl reduction
• Encourages yeast growth
• Helps achieve faster fermentation rate
• Inhibits growth of some microorganisms
• Reduces colour formation
• Helps achieve correct beer pH

Question 8

How do you calculate percentage evaporation from start and end of boil gravity?

Answer 8

Percentage evaporation = ((end gravity - start gravity) / end gravity) * 100.

Question 9

What is an acceptable percentage evaporation range during boiling?

Answer 9

4-10%.

Question 10

When do kettle finings need to be optimised?

Answer 10

Immediately if process parameters change, raw materials change, or changes in wort clarity are evident.

Question 11

What two parameters need to be balanced when optimising kettle finings?

Answer 11

• Wort clarity
• Compactness of the sediment

Question 12

How can you improve the utilisation of T90 hops during wort boiling?

Answer 12

• Increase wort pH
• Reduce trub volume
• Increase boil time
• Reduce wort gravity
• Increase boil temperature
• Change to a hop variety with a higher α-acid level
• Reduce fobbing/foaming
• Increase boil vigour

Question 13

What is the flavour threshold for DMS?

Answer 13

30-50 μg/L.

Question 14

What action should be taken if the wort DMS level is 220 μg/L?

Answer 14

Blend with a brew lower in DMS and take steps to reduce DMS in future brews.

Question 15

What are gallotannins and what do they do?

Answer 15

Gallotannins are polyphenols that remove metal ions by chelation, improving beer stability.

Question 16

What role do adjuncts play during wort boiling?

Answer 16

• Increase wort gravity
• Influence beer flavour, colour, and stability

Question 17

What is the role of hops during wort boiling?

Answer 17

• Provide bitterness and aroma
• Assist with trub formation

Question 18

What do kettle finings improve?

Answer 18

Trub formation and cold break level.

Question 19

What is the purpose of adding calcium ions during wort boiling?

Answer 19

• React with phosphate to produce calcium phosphate
• Help remove oxalic acid derived from malt

Question 20

What is the function of yeast food added during wort boiling?

Answer 20

Provides nutrients that yeast needs during fermentation.

Question 21

What is the effect of adding acids or sour wort during wort boiling?

Answer 21

Adjusts pH.

Question 22

What should be checked after reducing evaporation during boiling?

Answer 22

• Inactivation of malt enzymes
• Sterilisation of wort
• Concentration of wort by evaporation
• Development of flavour and colour
• Extraction and isomerisation of hop compounds
• Formation and precipitation of protein/polyphenol complexes

Question 23

How can you measure the development of flavour and colour in wort?

Answer 23

Using a spectrophotometer at 430 nm or gas chromatography mass spectrometry (GCMS).

Question 24

What methods can be used to evaluate protein/polyphenol complexes?

Answer 24

Using an Imhoff cone and the Kjeldahl method for nitrogen levels.

Question 25

What components of beer flavour should be measured?

Answer 25

Both bitterness and aroma ## Footnote These are important components contributing to the overall flavour profile of beer.

Question 26

How can the formation and precipitation of protein/polyphenol complexes be evaluated?

Answer 26

Using an Imhoff cone to assess sediment and wort clarity ## Footnote This method helps in visualizing the level of sediment produced during the brewing process.

Question 27

What method is used to determine the change in the level of coagulable protein?

Answer 27

Kjeldahl method ## Footnote This method analyzes nitrogen levels in wort after each boil.

Question 28

What temperatures should be used for boiling wort in the lab to measure nitrogen levels?

Answer 28

105-108°C ## Footnote This temperature range is necessary for effective boiling and nitrogen measurement.

Question 29

What is the purpose of removing nitrogenous material during wort boiling?

Answer 29

To prevent beer haze and fermentation problems ## Footnote Nitrogenous materials can cause haze or affect yeast performance in fermentation.

Question 30

How can fermentation rates and yeast viability be checked?

Answer 30

By ensuring they are unchanged after boiling ## Footnote Monitoring these factors is crucial for successful fermentation.

Question 31

What test can be done to assess haze in finished beer?

Answer 31

Measuring sensitive proteins or conducting haze forcing tests ## Footnote These tests help identify potential haze formation issues in packaged beer.

Question 32

What volatile flavour compound is primarily associated with unwanted flavours in beer?

Answer 32

DMS (Dimethyl Sulfide) ## Footnote DMS is known for imparting off-flavours in beer if not properly managed.

Question 33

Which method can be used to measure DMS levels?

Answer 33

GCMS (Gas Chromatography-Mass Spectrometry) ## Footnote GCMS is a powerful analytical tool for detecting and quantifying volatile compounds.

Question 34

What aldehydes characteristic of unboiled wort should be measured?

Answer 34

* Isobutyraldehyde * 3-methylbutanal * 2-methylbutanal * 3-methylthiopropionaldehyde ## Footnote These aldehydes can affect the flavour profile of the beer.

Question 35

What should the condensate produced in the stack drain smell like early in the boil?

Answer 35

Worty and grainy ## Footnote A desirable odour indicating proper boiling conditions.

Question 36

What method is used to measure foam stability in beer?

Answer 36

NIBEM method ## Footnote This method measures the rate of foam collapse over time.

Question 37

What proteins can be measured for foam stabilization analysis?

Answer 37

* Protein Z * LTP1 and its glycated form ## Footnote These proteins play a role in the stability of beer foam.

Question 38

How is the acidification of wort confirmed?

Answer 38

By measuring the pH with a pH meter ## Footnote Ensuring the pH is within specified limits is essential for brewing quality.