Making "Cake" flour out of GP or AP flour?

[sgtgoodie]

Today a friend of mine asked how to make Cake flour out of General purpose flour so I did a web search and came up with an "Ehow" answer. It says to subtract 2 Tbsp out of every cup of flour to be used replacing it with cornstarch. I should mention that it says to sift the flour first before counting cups. I thought I would find a Lbs/oz's formula for him to use but there's no mention in either of my textbooks (Professional Chef- CIA nor Professional Baking- Wayne Gisslen) of doing this. I use the flour with the correct protien level in my products and seldom use GP or AP flour. Anyone ever done this? Is there a formula in weights that can be used?

 

[petemccracken]

100 grams(AP) at, say, 12% protein = 12 grams protein

100 grams(cake flour) at, say, 9% protein = 9 grams protein

so, to create a mix of AP and starch that has 9 grams of protein, use 75 grams(AP) and 25 grams(Starch) or

divide the desired protein content by the AP protein content (9/12 or 0.75 in the example) and replace the difference with starch.

In the case you stated, one cup of flour is equivalent to 16 tablespoons, so removing 2 tablespoons is equivalent to 7/8ths or 0.875 so, if the AP/GP flour was, say, 12% protein, the resulting mixture would be 10.5% (12%*0.875), probably near the high end of protein % for cake flour.

 

[sgtgoodie]

Thanks Pete. I'm sure the formula will help considerably. Do you have any thoughts as to the quality of the final product when using this kind of mixture versus using regular cake flour? Also it sounds like the 2 Tbsp formula from the Ehow article may be more in line with making Pastry flour which is slightly higher in protien content than cake flour. Any thoughts there?

I'm forwarding any and all info to my old friend, I appreciate the input and I'm sure he will as well. Thanks!

 

[petemccracken]

First, I am NOT a baker so I hesitate to comment on the "quality" of the final mix. Cornstarch actually has about 0.7% protein, arrowroot about 0.8%, and potato starch 0%, so, the starch used to replace flour could also affect the quality as well as the flavor.

Second, after I posted, I thought about the "sifted" comment and how it might affect the end result. As typical with "volume" measurements of ingredients that have variable weight/volume ratios, there cannot be a 1:1 conversion, what may work for one may not work for  another.

IMHO, substitutions like this may work but should not replace the desirable choice, especially in commercial applications.

 

[sgtgoodie]

Yeah that's why I was trying to find him a reliable formula using weights rather than sifting and measuring with cups and Tablespoons. I just pay the extra to use teh cake flour in the first place myself. Maybe I should give the DIY formula a try sometime. Thanks.