1
Yeast and Starters
2
Yeast
• Yeast is found everywhere in nature
• 500 different kinds
• Baker’s yeast is one species:
Saccharomyces cerevisiae
• Yeast is a living organism
• It is unicellular
• Yeast has the ability to ferment carbohydrates once they are simple sugars
Fermentation
3
Definition:
The chemical process in which the enzymes naturally present in yeast convert sugars to a gas
and alcohol
Yeast
4
1
2
5
•
•
•
•
•
•
Functions of Yeast
•
•
•
•
6
Yeast is living and therefore requires several things in order to perform properly:
Moisture
Food
Temperature
Correct pH
Time
Structure
Leavening
Maturing the dough
Flavor
Aroma
Types of Yeast
Compressed
•
•
•
•
7
70% moisture
2-3 weeks in fridge
3-4 mths in freezer
Dissolve in 80F-90F water
Types of Yeast
Active Dry
• 8% moisture
• 1 pkg = 2 1/4 tsp = 1/4oz
• Dissolve in 105F-110F water
1
8
Types of Yeast
• Instant (SAF red label)
• Used at 1/3rd less compressed
• Used at 1/4 less than active dry
• 1 pkg. Active = SAF
2 1/4tsp = 1 1/2 tsp.
• Can be blended with flour directly
• Or added to the dough after 30-60 seconds of mix time
9
Straight Dough Method
VERY SIMPLE. . .
Put everything in the bowl and mix!
Know your type of yeast first: compressed and active dry yeast can be dissolved in the water
SAF or instant yeast must be dry mixed or sprinkled on formed dough
Don’t add all the flour in the recipe. Hold back some for kneading.
10
Starters & Longer Fermentations
Definition
• Any sourdough, sponge or yeasted piece of dough that is incorporated into a newly mixed bread
dough to boost fermentation
11
Starters
• Sponge starter
•
•
•
•
•
•
12
Poolish





•
13
Most basic: All the liquid in a recipe, enough flour to make a pancake like batter
For a quick rise, add all the yeast to the liquid and flour.
For a longer rise, add 1/3rd of the yeast amount
NO SALT, NO FAT
Let rise till active and bubbly, then add rest of ingredients
The less yeast you use and the longer you let it rise the more flavorful the resulting bread
Type of sponge method using less yeast
French-style pre-ferment
Much wetter
< 1% commercial yeast
For 2# dough 1/4tsp. Yeast
Why? Improved flavor, texture, shelf life, more flexibility to rising schedules
Poolish
• Soupy texture
• Like pancake batter
• Usually equal parts flour and water
FORMULA
2 1/2 cups br. Flour
1 1/2 cups water, r.t.
1/4 tsp. instant yeast
2
Biga
14
• Firm starter
• My favorite biga:
• 6 oz flour + 4 oz water
• 1/8 tsp. Yeast
• Let sit 12 hours or overnight
• OR
• 2 1/2 cup bread flour
• 1/2 tsp. instant yeast
• 3/4 cup water + 2 TB.
Biga + Poolish Side by Side
15
1
BIGA
2 1/2 cup bread flour
3/4 cup water + 2 TB.
1/2 tsp. instant yeast
2
POOLISH
2 1/2 cups bread flour
1 1/2 cups water, r.t.
1/4 tsp. instant yeast
16
Pre-ferment
• A piece of fermented dough left over from a previous batch
• This starter is added to a new batch of dough to give more depth of flavor
17
Sourdough Starter
• Natural leavening of wild yeast (Saccharomyces exigus) and bacteria (Lactobacillus
san francisco) captured in a mixture of flour and water
• Several starters can be used to capture these wild yeasts: rye flour, honey, organic
grapes, cumin
• It takes 10-14 days to build and then use a new sourdough starter
18
Sourdough Starter
• Saccharomyces exigus does not ferment maltose but ferments the other carbohydrates present in
flour - glucose, fructose, glucofructosans
• It also thrives in an acidic environment
• Lactobacillus san francisco does ferment maltose and produces acids that characteristically
flavor the bread
• Sourdough takes at least three days to make including building the starter
19
20
Sourdough Starter
Sour Dough Project
You need to keep a daily diary (legible).
3
Sour Dough Project
21
You will be supplied pineapple juice, diastatic malt powder, and flour
Sour Dough Project
22
You will need to supply your own spring water (or filtered water).
Sour Dough Project
23
You need to keep a daily diary (legible) of what you did (refreshments and times) and
how your starter looks, acts, and smells.
Sour Dough Project
24
Day 1 - 2:
Mix pineapple juice,
Wheat flour and malt powder. Stir 2-3 times a day. It is important to add
oxygen to the mixture.
Sour Dough Project
25
1
2
26
Day 3-4: Fermentation, add new refreshments
Day 4 or 5: Refreshing the culture add water and flour
Day 5 or later: Discard 1/2 the sponge and add more water and flour. Fermentation
should be happening
 Mother sponge: Building the starter. Mix 2/3 cup of the seed culture from day 5 or later
with 1 cup water and 2 1/3 cups flour. It should rise at least 1 1/2 - 2 times its volume
in 4 - 8 hours. Refrigerate overnight.
Sour Dough Project
Your mother sponge is now ready to be the starter for your bread.
Feeding: Your sourdough will need to be refreshed every so often 100 % flour: 75%
water: 33.3% starter (3 oz flour: 2 1/4 oz filtered water :1 oz starter). If you leave it
more than 2 weeks you will need more than 8 hours to revitalize it and you might need
to refresh it a couple of times with more flour and water.
27
Sour Dough Project
The project is due July 6.
This means you will turn in a diary and actually bring in the starter (no
matter what shape its in)!
28
4