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Raising Agents and Proportions

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Joined: 14 Mar 2014
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PostPosted: Fri Mar 14, 2014 4:45 pm    Post subject: Raising Agents and Proportions Reply with quote

Hi there, I am having a difficult time with baking sponge cakes. I can bake a cake using self raising flour from Tesco and it works fine, but if I use any other SR flour they tend to sink or over rise. With the Tesco flour I can use 4 eggs about 200 grams and 300 grams of flour but with the other flour it has to all be equal. I hope this hasn't been asked before, I feel like a Tesco flour addict Sad
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Joined: 19 Oct 2007
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Location: central PA

PostPosted: Fri Mar 14, 2014 9:55 pm    Post subject: Reply with quote

the generally accept ratio for self rising flour is
1.25 teaspoons of baking powder to 1 cup of plain flour

a teaspoon in volume if 5 ml; a cup of flour 130-135 grams

of course, it's difficult to know how much "other" flours are using, so if the Tesco brand works, stick with it.
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Joined: 18 Dec 2012
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PostPosted: Tue Mar 31, 2015 2:43 pm    Post subject: Reply with quote

Ok, here goes nothing.

baking powder is usually classified by its ROR (rate of reaction). That means a 27C warm dough is kneaded for 8 minutes and the ROR Value tells you how much % of the potential CO2 is released.

you should calculate 5,8-6g CO2 per kg flour used.

baking powders (usually) consist of two ingredients that interact with each other. one carries the CO2 the other carries an acid to release the CO2 (the acid carrier is usually coated for delayed effect).

There are CO2 carriers such as (others are deliberately ignored here because it would take to much time)
- sodium bicarbonate

sodium bicarbonate is by far the most common one to use (little or no off flavor and great synergies with chocolate - gives it a richer/deeper colour) and very reliable.

there are A LOT of acid carriers, but i will only go into detail about two of them.
- tetrasodium pyrophosphate (SAPP)
- glucono delta-lactone (GDL)

SAPP is often sub categorized into different RORs (usually SAPP15, SAPP28, SAPP40). That means that SAPP40 (ROR of 40) is releasing the CO2 very quick (CO2 starts being released before baking). SAPP15 on the other hand is delaying the CO2 release (strong oven spring). SAPP is the most common baking powder there is and it is a reliable and clean solution. You can use this in high fat/sugar environments like pound cakes or cookies.

GDL behaves very differently. Its releasing it's CO2 steady over time (almost yeast like). This makes it very interesting for sponge cakes (aid the whipping) or pizza.

baking powders such as (ABC or potassium bitartrate and the likes are ignored in this text because i am super lazy and they are easy to research and understand).

Now here is the kicker. you need different amounts of acid carrier to neutralize the CO2 carrier (don't want any off flavor). The neutralization factor of SAPP in combination with sodium bicarbonate (most common combination - works perfect).
you will need 1,37g of SAPP to neutralize 1g of sodium bicarbonate or 2,22g of GDL to neutralize the same amount of sodium bicarbonate.

but how much baking powder do you need? all the % values below are sodium bicarbonate (do the math and add SAPP or GDL accordingly)
sponge cake 1-1,5% flour weight (SAPP20-28)
brownies 0,2% flour weight (SAPP28)
pound cake 0,5-1,2% flour weight (SAPP15-28)
waffles 0,3-0,8% flour weight (SAPP40)
pizza 1,2-1,5% flour weight (SAPP20-28, GDL)
shortbread 0,3-0,5% flour weight (SAPP28-40)
muffin 1,6-2,5% flour weight (SAPP15-28)
doughnut 1,3-1,5% flour weight (SAPP40)
scones 1,6-2% flour weight (SAPP15-28, GDL)

i think this should cover the very basics without going to much into detail.
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