Yeast and Bacteria

Question 1

What are the two primary yeasts used for brewing beer?

Answer 1

• Ale yeasts
• Lager yeasts

Question 2

What is yeast?

Answer 2

Single-celled organisms that eat sugar and produce certain by-products, such as alcohol, carbon dioxide, heat, and aromas.

Question 3

What is a yeast strain?

Answer 3

One of thousands of different yeast varieties - each slightly different.

Question 4

What is ambient yeast?

Answer 4

Yeast that is naturally on surfaces and in the air around us - often adapted to a cetain area and able to produce unique aromas and flavors.

Question 5

What type of yeast is most commomly used to produce beer today?

Answer 5

Cultured yeast strains produced in a lab environment, and packaged for commercial use by a specialty supplier.

Question 6

What is Sacchromyces cerevisiae?

Answer 6

Ale yeast strain

Question 7

What is one of the benefits of replicating the same yeast strains over and over again?

Answer 7

Consistency in the brewing style and a reliable outcome of the final beer.

Question 8

What is meant by pitching yeast?

Answer 8

Adding or innoculating yeast to a wort.

Question 9

What is a benefit of using ambient yeast to brew a beer?

Answer 9

Additional complexity in the beer style that may not be achievable with commercial yeast.

Question 10

True or False.

All yeast ferment to the same level of attenuation.

Answer 10

False

Different yeast strains will have different abilities to ferment sugars in a wort.

Question 11

Which produce more fruity esters - ale or lager yeast?

Answer 11

Ale yeast

Question 12

What are perceived as fruity aromas?

Answer 12

Esters

Question 13

What are perceived as spicy aromas?

Answer 13

Phenols

Question 14

How many strains of ale yeast are there?

Answer 14

1,500 to 2,000

Question 15

What are the distinctive aromas of Abbey ale yeast?

Answer 15

• Fruity:
  
  • Banana
  • Apple
  • Pear
  • Plum
• Spicy:
  
  • Peppercorn
  • Clove

Question 16

What are the distinctive aromas of Saison yeast?

Answer 16

• Fruity:
  
  • Citrus
  • Stone fruit
  • Pome fruit
• Spicy:
  
  • White pepper
  • Black pepper

Question 17

What are the distinctive aromas of Witbier yeast?

Answer 17

• Subtle fruity esters.
• Subtle clove spice phenols.

Question 18

What are the distinctive aromas of Weizen yeast?

Answer 18

Distinctive spice (clove) aromas from phenols, with balanced fruity esters of banana.

Question 19

What are the distinctive aromas of British ale yeast?

Answer 19

• Fruity: apple, pear, dried fruits
• No phenols

Question 20

What are the distinctive aromas of American ale yeast.

Answer 20

Very subtle, low levels of esters and no phenols. Slight fruity aroma, if anything.

Question 21

Fermentation temperature range for ale yeasts.

Answer 21

Warm
64-75°F / 18-24°C

Question 22

Fermentation time for ale yeasts.

Answer 22

Quick
3-5 days

Question 23

Yeast and Bacteria

What is saccharomayces pastorianus?

Answer 23

Lager yeast

Question 24

Fermentation temperature for lager yeast.

Answer 24

Cool
45-59°F / 7-15°C

Question 25

Fermentation **time** for **lager** yeast.

Answer 25

**Long** 7-14 days

Question 26

Overall **aroma impact** of lager yeast on the final beer style (typically)?

Answer 26

**Subtle** aromas

Question 27

What is *Lagern*?

Answer 27

German word meaning *to store*. ## Footnote As in to store something for a period of time. The root of **lager**.

Question 28

What is the maturation **condition** and **period** for lagers?

Answer 28

**Cool** and **long**.

Question 29

What's the number of different **lager yeast strains**?

Answer 29

About **150** strains.

Question 30

What is the term for **non-cultured** yeast and bacteria?

Answer 30

Ambient

Question 31

What is a **Brett**?

Answer 31

Short for **Brettanomyces**, is a type of yeast used to add complexity to some beers.

Question 32

What is the overall **aroma** impact of **Brettanomyces** on the final beer?

Answer 32

Fruity esters: * **Tropical** fruit (pineapple) * **Stone** fruit (peach) * **Farmyard** notes (hay, horse blanket, earth, leather)

Question 33

Given enough time, what **beer style** can Brettanomyces create?

Answer 33

Notably dry style beers. ## Footnote This is due to the fact that Brettanomyces can ferment more complex sugars than ordinary yeast.

Question 34

What is the most **common** type of **bacteria** used in beer production?

Answer 34

**Lactic acid** bacteria

Question 35

Aside from beer, what **other food products** are created with lactic acid bacteria?

Answer 35

* Yogurt * Kimchi

Question 36

What can lactic acid bacteria **contribute** to a beer's **style**?

Answer 36

Acidity

Question 37

Aside from beer, what **other food products** are created with acetic acid bacteria?

Answer 37

Vinegar

Question 38

What can **acetic acid** contribute to a beer's overall style?

Answer 38

A **vinegar-like** acidity and aroma. ## Footnote Low levels are acceptable, high levels are not.

Question 39

The style and production of **Flanders Red** depends on what bacteria for added **complexity**?

Answer 39

Low levels of **acetic acid** bacteria.