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Leaven for Bread, Pizza, Focaccia and Cakes

or how to make bread and pizza at home


version 2008/12/27
Azyme Bread  Bread with yeast dough just cooked
Focaccia with semi-whole flour just cooked  Roses Pie just ovened

The two most important elements that influence leaven are yeast and flour.

Yeast is used in almost all oven products: savoury (bread, pizza, ...) and not (cakes, pies, ...).
About this there's a very important notice to be done about our quick way of life, regarding the leaven time. In almost all the recipes it's only 2 hours long at most, and for cakes it's usually 0, but this is absolutely WRONG!.
By reducing the levure time forces you to put a huge amount of yeast, but we all know the most yeast we get the less digestive the product will be !. But we have to say, about reducing the yeast dose, further to the longer leaven times, there's the risk to get a bad grow and this is the main reason why the quantity is exagerated: to avoid risks. We can say that natural leaven sometimes has 'paturnie' and all depends on the cook ability to correctly evaluate the influence of the different ambient factors.
A good thing is that bakers are getting sensitive to this matter and are starting producing bread and pizza with reduced yeast content or 'natural leaven' (20-22 hours).
We here do not want to argument about the different recipes but would like anyway to present some practical examples, based on our home experience, just to give a closer idea of what we are speaking about. The goal si to convince ourselves to reduce the amount of yeast and get taster and more digestible products.


Yeast

leaven (after 15 hours) using small amounts of bakers yeast
There are diferent kinds of yeast:
  • 'brewers yeast' or 'ale yeast' or 'bakers yeast' or 'budding yeast' by the ferment 'saccharomyces cerevisiae' (a microorganisms), fresh or dried granular (to be melted in warm water). It is used for baking and brewing.
  • instantaneous powder (mainly used for cakes), composed by different chermical principles: sodium bicarbonate, bisodic diphosfate, ...
    This kind of yeast does not require leaven time: starts acting at oven temperature; just make and oven. Used for cakes.
  • 'Cream of tartar' powder (mainly used for cakes), composed by chermical principles naturally derived from wine production: potassium acid tartrate, sodium bicarbonate, ...
    This kind of yeast does not require leaven time: starts acting when melted.
  • 'natural yeast' or 'mother yeast' or 'yeast dough': you get it by leaving to rest some of the bread 'paste' (without yeast) for some days.
    The microorganisms (see note) leaving on the air colonize the dough and eat the substances inside, this makes leaven start up.
    You can make it by adding some yogurt (as Tilde does) or fruit juice (as Esme tells in the book "Bread and Chocolate" by Lynch Sarah-Kate, but we won't reveal you which kind of fruit: you must read the book), or simply some sugar or honey (microorganisms are greedy).
    Unfortunately we must say it's very delicate and must be 'renewed' soon (weekly).
    Maybe in the future we will enter deeply in this theme ...
    in the meantime here are some interesting links:
    natural leaven by Simili sisters (in italian but with a lot of photos)
    lievito naturale di Gennarino (in italian, scientific oriented)
    detailed natural yeast info (in italian)
  • recently introduced on the market you can find dried 'natural yeast', but we never used it.
All of the yeasts bring to a common result: they produce, even in several different ways, carbon dioxide: the responsible of leaven. Carbon dioxide is produced immediately as the yeast is melted or by oven temperature or as a bio-chermical reaction (see microorganisms).
Obviously any yeast gives its own taste to bread, pizza or cake.

Flour

Flour is as much important as yeast because in order to get a volume increase it must have the capacity (once melted with water) to make a sufficient elastic structure: the glutinic network, capable of retaining gases created by leaven. In other words dough must be capable of behaving like a sort of baloon capable of inflating without breaking.
Gluten has this elastic propriety. And for this reason the most important flour parameter is the strength, measured by a number followed by the letter W.
This information is generally not reported on package because only field experts can evaluate which is the best strength for each recipe.
The greater is gluten amount, the greater is flour strength and the greater leaven will be.
To get a more precise idea flours are divided in 4 strength categories:
  • Weak or soft or cake flours (up to 170 W).
    For all products that do not require much leaven such as cookies, wafers, breadsticks, azime bread and cakes.
  • Medium or pastry flours (from 180 W to 260 W).
    The most commonly used, to make bread, pizza and pies.
  • Hard flours (from 280 W to 350 W).
    For products that require a long leaven time (for instance bread with natural yeast).
  • Special flours (more then 350 W)
    Used only to be mixed with other flours to get the desired strength. The Manitoba flour is one of these.
Cereals flours are all VERY weak.
Commonly found in shops are soft-medium flours and the Manitoba flour (original from Manitoba, Canada) with 400 W !.
Useful to be known is that all the different kinds of flours (wheat and not) can be safely mixed together, the resulting strength of the mix is a weighted medium of the strength of the single flours.
Example: mixing at 50% 400 W wheat flour with 0 W barley flour, you get a 200 W mix.

What's the difference between 00 (white), 0 (plain) and whole flour ?

Many kind of wheat exists: common wheat, durum, einkorn, spelt, ...
In Italy common wheat flour is classified of type 00, 0, 1, 2 (2 = whole).
This has nothing in common with 'strength'. It relates to sifting the flour from brans.
The type is determined by accurately measuring the amount of resulting minerals.
00 (white) flour is the most pure (filtered) and is commonly used for cakes but is ok for any use,
0 (plain) flour has a low % of bran and is the best for bread and pasta but is ok too for any use.
A 100% whole flour has all of the bran naturally present in the grain.

Lets' pay attention to Bran

Generally speaking, cereals require a cerful preparation because they contain some antinutrients that can cause health problems.
Fitic acid, for instance, is an organic acid linked with phosphorous. It is found mainly in bran and peel of seeds. Unprocessed fitic acid can combine with calcium, magnesium, copper, iron and zinc in our digestive tract and block their absorption. Correct cereal preparation is a gentle procedure requiring a long fermentation, using natural yeast in bread preparation. These processes neutralize fitic acid and enzyme inibitors. Vitaminic content increases, particularly vitamins of group B. To get further information you can visit this site.
Studies from the University of Baleares Islands have shown that fitic acid (included in a natural and balanced diet) has important antioxidant power, see here.

Put our hands in mixture

But let's go deeply to results; let's take as an example the bread as we are used to here in Italy.
Please note that data here reported is only indicative. The goal now is not to get the ideal bread but just to get the maximun leaven with the minimum amount of yeast.
Then once understood the way of working, you can open your mind and modify/create a new recipe, by mixing different kind of yeast to get the best bread (or other oven product) ever made or just to make better the things you are already used to.
Bread made with 1/2 Kg (1 lb) flour
Ref.No. yeast leaven time volume increment /
leaven quality
taste hardness typical example
n.0 0 0 0 /
'very heavy' bread
- normal difficulty azimo, carasau and many other breads
n.1 brewers yeast
25 gr
2 hours double /
'heavy' bread
leaven tastes normal difficulty quick home or 'hurry' baker made bread
n.2 brewers yeast
15 gr
3 hours double /
'heavy' bread
leaven tastes none: put all into the machine and plug in the power automatic bread machines
n.3 brewers yeast
2 gr
15 + 4 hours double /
bread high and soft
good 'delicate' leaven 'judicious' baker made bread
n.4 natural yeast 10 + 4 + hours see Note1 /
not too soft
lightly acidulous 'VERY delicate' leaven traditional home made bread
Times reported as an addition (f.i. 15 + 4 hours) mean leaven is divided in 2+ steps, a first main leaven, a re-mixing, again leaven, ....


NOTE 1: when using mother yeast the quantity of it in relation to the the dough is big, so it is difficult to make a comparison with standard baking yeast.
Anyway the bread results not paricularly grown and less soft related to normal yeast. But taste is wonderful, lightly acidulous. The greater advantage is digestivity: you can eat big quantities without feeling satisfied.

When you have to deal with long times a lot of different factors influence leaven, the main one is temperature.

Trick: when you have some time left, test how leaven proceeds along the hours: you will notice a constant volume grow until it stops and then shrink: microorganisms have eaten all the food !
Quantifying the time for the maximum grow is very useful. The test must be repeated in the different periods of the year. A very good result is volume doubling, going further the risk is to break the glutinic net. A very important factor is the quality of flour and its 'strength'.
Professional bakers use constant temperature and humidity chambers to always get the best possible result.
The ideal temperature for leaven is 30-38 C (86-100 F), to get it you can use one of these tricks.
Put dough:
  • in a close environment (oven switched off for instance) within some warm water cans;
  • in oven (switched off) leaving the internal light on: warm generated by bulb is enough.
  • in a can on the refrigerator: the serpentine cooler on the back side becomes warm.
In any way NEVER put dough over the radiator: it's too warm.

Trick: regarding water there are a couple of things to keep in mind.
It must be "warm" i.e. at 40C (100F) abt temperature. If too much warm the risk is to let amides interfere with gluten or to kill ferments, if too cold leaven process gets stopped.
In any way it is not really important water temperature; what really matter is dough temperature: add cold water if too warm or add warmer water if it is too cold.
Chlorine interferes with leaven, use mineral water or leave tap water to rest for some hours. Best would be to use source water.


Trick: manitoba flour has a great amount of glutin and this helps leaven. Mixed at 50% with normal flour is the best solution.
Trick: when making a cake with mother yeast, remember to abound with honey (or sugar) because the longer is the leaven time the bigger is the amount of sugar eaten by microorganisms, and when you eat a cake you have to feel sugar, but if the amount is not enough both for you and for microorganisms, ther's the risk that they eaten it all !

Trick: when you make bread with mother yeast, the best solution is to make 1 Kg (2 lb) bread because microorganisms do not die during cooking: in the center some survive; this area is called the poult. If you wait one day after cooking before consuming it, microorganisms have the time to spread-out and reach all of the volume. This is good for us: digestibility increases and the immune system gets benefits !.

Ok and now it's up to you (just have to click-on):
bread recipe made upon method n.0,
bread and focaccia (bun) recipes made upon method n.3, and
bread and focaccia (bun) recipes made upon method n.4.


microorganisms

Microorganisms or ferments are exactly bacteria that instead of being enemies, they work for us, allowing to appreciate products like yogurt, cheese, wine, beer.
Adverts unfortunately has turned us thinking that bacteria are bad while milk ferments are good, help keeping our regularity, but we are always speaking about bacteria, even if not the same.
Leaven and yeast have probably been discovered in a random way and even Sumerians new various types of bier.
And what about yogurt, known since ancient times, before the discovery The first leavened bread historically proofed is from Egyptians.
of the cheese production.
It's incredible that only in the half 1800 Louis Pasteur discovered the exact mechanism of leaven: bacteria eat the sugar (gained from the starch of flour) and produce carbon dioxide: the responsible of dough grow.


Stefano and Tilde
To argument about this, get into the blog by clicking here.

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