Check your expert knowledge

 CHECK YOUR EXPERT KNOWLEDGE

How solid is your expert knowledge when it comes to beer brewing? Whether craftsmanship or extensive expertise in the field of microbiology and food chemistry: A brewer needs the knowledge and overview of the manufacturing process. Therefore, the questions in this issue cover a broad range of facts which a professional brewer should be familiar with.

1. There are different types of dry hopping. From the technological point of view, which one is the most efficient technology without losing beer quality?

a) Hop dosage in an open fermenting tub b) Hop dosage in the CCV c) Hop dosage in the storage tank d) Dosage of hop pellets directly into the bottle

2. A barley kernel consists of about 12 to 14 % water and the „dry matter“. Which carbon hydrate is the major component of the dry matter in barley?

a) Cellulose b) Maltose c) Starch d) Glucose e) Dextrin

3. Unlike the hydrofluorocarbons used in the past, ammonia (NH3) as a refrigerant is not considered ozone-depleting. Nevertheless, there are certain risks associated with handling ammonia.

Which ones (3)?

a) Ammonia is a highly corrosive gas. b) Ammonia is explosive at very high temperature especially when mixed with oxygen. c) Ammonia is a substance hazardous to water. d) Ammonia is not soluble in water.

4. The optimal pitching yeast in a brewery should have special properties. Which of the following is not one of them?

a) Thick consistency b) The number of dead yeast cells should not exceed 3 % c) High vitality d) Immediate begin to fermentation e) High fermentation power

5. Before the yeast proliferates strongly after the pitching, it goes through a latency and fermentation phase. This is followed by the multiplication phase. What is this phase also called?

a) Lag phase b) Log phase c) Stationary phase d) Sprouting phase e) Ascending-phase

6. If the malting barley is too wet on delivery, there is a risk that the barley will mould during storage. Which of the following statements regarding water content is incorrect?

a) If the water content exceeds 17 %, the barley should be dried.

Photo: ew

b) A water content of 12 % is ideal for long-term storage. c) If the water content is high, the barley should be stored in a cool place. d) At a water content of over 15 %, respiration increases very sharply. e) The respiration loss does not depend on the water content of the stored barley.

7. In addition to aroma, hops also bring bitterness to the beer. The bitterness of beer is described in Bitterness Units (BU). 1 BU is approximately...

a) 1 mg iso-alpha acid per hL of wort. b) 1 mg iso-alpha acid per L of sales beer. c) 1 mg iso-alpha acid per 100 L wort. d) 1 mg iso-alpha acid per L wort. e) 1 g hop pellets per hL wort.

8. Enzymes play an important role in malting and brewing. What are enzymes?

a) Energy suppliers – they provide energy for metabolic processes b) Signal transducers – they transmit signals to other messengers c) Biocatalysts – they accelerate the transformation of chemical substances d) Inhibitors – they slow down metabolic transformations e) Moderators – they initiate substance transformations

9. Which of the following enzymes is not yet detectable in the ungerminated barley grain, but is only formed during germination?

a) Alpha-amylase b) Beta-amylase c) Peptidases d) Exo-beta-glucanases e) Proteinases

Answers

1. c) There are several technologies for dry hopping. Dosing hop pellets into the storage tank is one of the most efficient ways.

2. c) Starch (C6H10O5)n is the most important constituent of barley and makes up 63 % of the dry matter. The starch of a barley kernel consists of about 20 % amylose (long, unbranched helical glucose chains) and 80 % amylopectin (very long, branched glucose chains).

3. a), b), c) Ammonia (NH3) is a very corrosive gas which can cause serious injuries. Any direct contact has to be avoided and strict safety measures have to be employed.

4. d) Immediately after pitching, the yeast cells must first multiply. Therefore, the wort is aerated to enable the yeast to respire and thus to multiply quickly. After the oxygen in the wort has been consumed the yeast cells change their metabolism and (anaerobic) fermentation begins.

5. b) In the phase of exponential or logarithmic growth (log phase), the growth rate of the yeast is constant and maximal. The generation time (the time period during which the cell number doubles) is minimal during this phase. In this phase the yeast is at its most vital.

6. e) Since the respiration of the barley kernels increases rapidly at a water content of more than 15 %, it should be dried in order to avoid respiration losses during the storage. (And also to avoid the mould formation!)

7. b) The bitterness of a beer is expressed in bitterness units (BU). According to the definition by the European Brewery Convention (EBC) 1 BU refers to the content of 1 milligram bitter substances (iso-alpha-acids) per liter of beer.

8. c) Biocatalysts: Enzymes are proteins that act as biological catalysts by accelerating biochemical reactions. They increase the reaction rate by lowering its activation energy for a specific reaction.

9. a) Alpha-amylase is not detectable in ungerminated barley. Most of the alpha-amylase is formed during the malting process on the third and fourth day of germination. Betaamylase is already present in large amounts in ungerminated barley.

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