Some interesting results - stirring the flour every 10 secs during microwaving eliminates the toasting effect. I also compared oven and microwave-treated flours: see http://amerrierworld.wordpress.com/2008/11/06/treatment-of-choice/
:-)

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I'm working on it - may have some results later today/tomorrow :-)

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Sorry!

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I don't mean to change the subject (In a sense) but is there any way to overcome the strange roasted flavour that the microwave treated flour imparts?

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I don't mean to change the subject (In a sense) but is there any way to overcome the strange roasted flavour that the microwave treated flour imparts?

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I don't mean to change the subject (In a sense) but is there any way to overcome the strange roasted flavour that the microwave treated flour imparts?

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I haven't tried heating flour in a conventional oven (yet!), but I have read about it. In relation to pancake springiness, heat-treatment at 120 degrees C for 2 hours in an oven has been shown to have the same improving effect as chlorination (Seguchi, 1990). Interestingly, incubation of starch granules at room temperature for 233 days also has the same effects on the starch granule's oil-binding capacity (Seguchi, 1993). However, more recent scientific analysis suggests a different mechanism of starch gelatinisation when the granules are heated in a microwave compared to conduction heating (Palav & Seetharaman, 2006). Microwave heating (but not conduction heating) results in granule rupture, which in turn has an effect on the rheological behaviour of the dough or batter.

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I haven't tried heating flour in a conventional oven (yet!), but I have read about it. In relation to pancake spriginess, heat-treatment at 120 degrees C for 2 hours in an oven has been shown to have the same improving effect as chlorination (Seguchi, 1990). Interestingly, incubation of starch granules at room temperature for 233 days also has the same effects on the starch granule's oil-binding capacity (Seguchi, 1993). However, more recent scientific analysis suggests a different mechanism of starch gelatinisation when the granules are heated in a microwave compared to conduction heating (Palav & Seetharaman, 2006). Microwave heating (but not conduction heating) results in granule rupture, which in turn has an effect on the rheological behaviour of the dough or batter.

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It does! It's actually being sold in the supermarket (coles) as a "cake improver" which i was shocked to see, as the only other place i had heard about it was from Kate's fantastic blog and the experimental reports. Though, the packaging fails to specify the quantity needed per a batter, and doesn't mention anything about heat treated flour, which is a shame, as the experiments on Xanthan were all carried out with HT flour! What can you expect :P

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Actually, i have been doing it! I sift a fine layer of flour onto a sheet pan lined with baking paper, and put it in a preheated 160 degree (Celsius) oven for approx. half an hour, stirring once or twice (basically until it reaches 130 degrees) :) I find that the flour is much easier to deal with, as it doesn't stick to utensils as ferociously and there is less clumping and wastage. When i bake i also add 1/4 teaspoon of Xanthan, which weighs about 1 gram, and is the closest i can get to the specified .12% (weight of the batter) which is applicable to most batters.

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You'll have to excuse me, as this may be quite a silly question but is there any reason why we treat flour in the microwave and not the oven?

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Then, yes, it is high-ratio. Flour = 7 oz, Potato starch = 2 oz, Sugar = 14 oz.

So does using a mixture of starch and flour (and NOT microwaving) not work for high-ratio recipes?

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The "high-ratio" method of mixing cakes is used when the weight of sugar is greater than or equal to the weight of the flour (and other starches). Rose's method of mixing in the Cake Bible is a variation on the "high-ratio" method. For more information on methods of cake mixing, I recommend Shirley Corriher's book "Cookwise."

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Does your pasta flour have the same protein % as the unbleached AP flour in the US?

What classifies it as a high-ratio recipe? I've heard of the term before but never really did research to find a definition.

The recipe was posted in The Modesto Bee and can be found by searching "Warren Brown yellow butter cake". Don't know if I should post other recipes or not.

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Yes, I did try this - see http://amerrierworld.wordpress.com/2007/10/30/more-questions-of-flour/ :-)
It didn't work for Rose's recipe ... was Warren Brown's a high-ratio recipe too?

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I just stumbled across a recipe from Warren Brown's (from CakeLove in DC)Yellow Butter Cake from his new book. In case you weren't aware, he advocates all natural ingredients (which explains the absence of a red velvet cake on his menu) so I assume he does not consider bleached/cake flour natural.

In the yellow butter cake recipe, he uses 7 oz unbleached AP flour and 2 oz potato starch. I assume this combination is used to achieve the same affect of cake flour without the bleaching process?

I do not have his book and the recipe online mentions nothing about heat treating the flour.

Kate ~ Did you ever try NOT heat treating and just subbing some of the unbleached flour with startch? If so, how did it work? (Sorry if I missed it in the previous posts or your blog.)

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Are you in NSW? If so, absolutely, I'll gladly go halves in a bag!! PM me via the forums :) Thanks Lauren!

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Thanks for the advice, Cate - it's produced by Allied Mills, and sold in 25kg bags. I'm not completely sure of how to buy it (directly from Allied or a wholesale supplier)... Though if you're interested in going halves in a bag, it would be fab!

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Wow, great news Lauren, I'm in Aus too, any chance you could email me the details of the supplier of this flour?
Thanks!

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Lauren, I would definitely try that flour, heat treated, and even if high protein.

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Hello, I’ve managed to source a locally produced heat treated flour (I’m living in Aus) which is very exciting, but the protein content is 11.5%... I just want to clarify that this will be relatively useless for cakes, cookies and pastries due to this high protein content.

Many thanks :)

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brilliant Kate, thanks for sharing pictures on your blog.

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Just to report that this works very well++ for Rose's Perfect Chocolate Butter Cake (All American, in the US version, I think ??) ... if anyone has access to McDougall's Supreme Sponge SR Flour ... http://amerrierworld.wordpress.com/2008/05/27/colour-or-crumb/

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I found this Gold Medal timetable interesting:

http://www.gmflour.com/gmflour/ourheritage.asp

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BTW: I'm still on the fence as to whether this freezing is actually the reason I get better results with unbleached flour as I really haven't tested it against non-frozen unbleached flour... and I think Kate Flour is still superior (big hat tip to Kate - thank you!)

I still wonder if freezing is adding not subtracting moisture which means it should have the opposite effect, yet do doesn't seem to - which is why I'm so confused!!!

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Thanks for the feedback here and one the forum Hector.

Oh and FYI to anyone wanting to try freezing unbleached flour in Australia: I use the Anchor Cake, Biscuit and Pastry Flour (prior to it being available I used Anchor Plain Flour) and freeze for at least 48 hours before I decant into my flour cansiter.

And...as Hector mentions on the forum remember to wait until the flour reaches room temperature again before you use it :)

P.S. I still find Kate-Flour's method of heating the flour gives a slightly better texture but when time is short my frozen flour gives an acceptable (if not fully Rose-worthy!!) result.

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Annie, be sure to "watch" Rose, lecturing on flour. It is the latest.

http://www.realbakingwithrose.com/2008/01/hectors_great_video_tape_of_my.html

I've been baking with bleached AP flour for years, in the USA, and all cakes were acceptable to me. Using Cake Flour will give you a finer more tender crumb and texture, and I believe Cake Flour makes the cakes tastier, too.

Cake Flour has a more critical effect on butter based cakes, than on Genoise/Biscuit. That is my belief.

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Hector, thanks for the information on freezing flour. It makes a lot of sense. I do not wish to use 'Kate flour' as I only use organic and felt that microwaving it could render it non-organic. I shall definitely try the freezing method though.

I have to say that I have lots of success with Rose's cakes here in the UK using organic unbleached flour. However, when I lived in the States and used cake flour (from KAF) the texture of my cakes was quite different. In fact, after moving, I made the Pineapple upside-down cake with some cake flour I had sent from the States (KAF will send it air-mail but it's expensive!) and also using unbleached organic. They both looked great and rose correctly but it was the texture that made the real difference. The texture with cake flour is much finer and more delicate. I didn't know about the blog then or would have posted pictures.

I'm off to freeze some flour now!

Annie

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Kate, there is a interesting discussion on the forums regarding freezing unbleached flour and how it makes it ok for cakes.

Cate. Posted: 14 May 2008 12:01 AM

Thanks Hector and Patrincia - I appreciate your time and feedback!!!

My apologies but I think maybe my original post was too wordy, I’ll try and be succinct:

My main query is this:

I have UNbleached flour here in Australia....but
I have not had as much of the same problems others have with Unbleached flour affecting the results of TCB recipes.
I was wondering why and thought maybe it’s because I routinely freeze the flour before use.
Does anyone know if freezing flour affects it chemically ?

Warm regards,
Cate

hectorwong

Posted: 14 May 2008 02:46 PM

Cate, more than chemically, I think it is physics.

Water expands when frozen. Cell walls of plants have cellulose, which isn’t flexible. When frozen, the water contained in each cell bursts the cell walls. This is why when you freeze crisp vegetables, when thawed they are soft. Something similar happens to flour when frozen, although not very obvious since the water content in flour is low. Flour is plant. I assume that this is a similar effect to bleaching or heat treating flour, the point of cake flour is to make it more ready to absorb liquid.

Cell walls of animals don’t have cellulose, and are flexible. When frozen, the water contained in each cell will expand and stretch the cell walls, mostly not bursting them. This is why the texture of frozen meat, for example, is almost the same fresh than thawed.

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And most of the protein content is already listed in the back of the bread bible by brand.

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Hi Jo-Ann - I think you should be able to get that info from the various flour manufacturers.

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HI Rose
Love your site and books...
Have a question..
How do I calculate the % protein in each of my different kinds of flour?
Thanks
Keep up the great work

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I did the cake test again with corn starch. Still not much difference, though my test was marred a a procedural irregularity.

http://members.cox.net/jsam/baking/cakes2.html

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It's certainly the case that my unbleached untreated cookies do not look like yours. Also my bleached and unbleached cookies resemble each other. I can use either type of flour without much change. However, I have not tested chlorine bleached cake flour. (I don't tend to keep cake flour around.)

If you only change the flour, how does the change affect the spread?

Quantity of flour certainly matters. (I have a recipe which calls for 160g flour and I had to experiment to find the right flour level because my cookies were spreading dramatically less than the ones depicted in the cookbook...which was from Europe.

Does protein content matter? Higher protein flours are supposed to absorb more water (does this depend specifically on the gluten formation process?) If so, could differences in protein be responsible?

In the interest of covering all the variables, I would imagine that oven temperature could have some effect if our ovens aren't the same. It also looks like your cookie sheet is darker than mine. Could this have an effect? Could definitely lead to increased browning. (When I switched from darkish steel cookie sheets to thicker aluminum ones I noticed that things needed to cook for a couple more minutes.)

Another possible variable is brown sugar. I have heard that it's difficult to get outside the US. The brown sugar contributes acid to the batter which is supposed to speed setting of the cookies, so reducing the acid could make them spread more.

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Thank you ever so much for testing these cookies, Adrian - it's the first time I've seen them directly against examples of bleached-flour cookies. I'm wondering ... although your unbleached/untreated cookies spread more than the microwaved-flour cookies, they don't appear to have spread quite as much as my own untreated cookies did (same recipe). Mine were like large cow-pats and were very thin and caramelized around the edges. Perhaps there is a greater difference between our plain and your unbleached All-Purpose flour than I'd imagined - which would give differences too when the same flours are microwaved, I'd assume ...?

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I guess another consideration. Microwaving the flour is driving off moisture so by using the same weight of flour I'm replacing liquid in the recipe with starch and protein. Perhaps I should be weighing the flour before microwaving and then using that ratio to formulate the recipe? (This is hard because I find at least that a bunch of flour sticks to the plate, the spoon, the thermometer, etc. And some remains in clumps that don't make it through the sifter.)

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I agree: microwaving the flour is a nuisance.

I've tested the same recipe that Kate used for her cookie test. I find it remarkable how small changes in the recipe for cookies can lead to large changes in the resulting texture. It seems like cakes are not as sensitive. (Or maybe I'm just less aware of the nuance of cake texture.)

I've written up my results at http://members.cox.net/jsam/baking/cookie2.html
including several pictures.

These cookies are thicker and cakier than the ones I made before. The treated flour gave much thicker cookies that didn't spread as much. Despite this, the actual texture of the cookies seemed very similar between the three types. As before, the unbleached flour cookie browned the most. The treated flour cookies browned the least and came out looking pale compared to the other two.

I assume that the more cake-like texture means that flour is playing a more important role. This may explain why the treatment made a more pronounced difference for this recipe than for my recipe.

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seconded ;-)

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Rose, can you get an electron microscope of Kate's microwaved flour? It will be interesting to see the physical shapes of the flour particles, as I suspect that microwaving flour must expand the starch granules into Wondra like particles like microwaving popcorn!

It will be magical if all we need to stock is a high protein unbleached bread flour, and with the microwave we can convert it into Kate's gold for cakes and for pastry!

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A rough surface would be important when it comes to holding butter in suspension.

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As far as I understand it Adrian, bleaching and heat-treatment accelerate the natural processes of aging in flour. Oxidation of carotenoid pigments leads to protein denaturation. This promotes gelatinization of the starch granules, thereby increasing their absorption properties - which improves the flour's baking performance.

Another possible factor to consider is the way in which both chemical and heat processes attack the surface of the starch molecules and roughen them. Photos of starch molecules after microwaving suggest that the speed of agitation literally blasts them apart. The authors of this study write that "the data showed that rearrangements restricted to sections of the starch molecules resulted in the formation of new crystallites of different stabilities and led to a more ordered crystalline array." - see http://tinyurl.com/28tve7

Hope that helps ...

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I understand the point about treatment of flour (possibly) reducing gluten formation.

But if the goal is simply to reduce gluten formation, why not just bake with pure starch, or add starch to the flour? That's easier than bleaching or heat treating. If flour treatment worked by simply reducing gluten formation then we could get the same result by using starch instead of flour. Something else must be going on, presumably having to do with the gelatinization of the starch referred to above. And that something else is presumably what's important. (I mentioned above the acidification that chlorine bleaching causes.)

I expect that we want some gluten formation in a cake to give it structure. If I understand correctly, Rose thought that the treated bleached flour performed worse (lower rise) because of impaired gluten formation resulting from the double treatment.

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Hi, I'm trying to think of a way to clarify this whole protein/gluten/bleaching/heat treating thing...let's see if I can say something that will help.

I think the most important point is that the protein content of flour is NOT the same thing as its gluten-forming potential. But, people often use the protein content as a "rough guide" to the gluten-forming potential.

"Protein" is a very general term -- all sorts of molecules qualify as proteins and all sorts of things contain them. Wheat contains two special proteins, glutenin and gliadin, that combine to make this magical thing called gluten that gives bread such a great texture. The important thing is that wheat flours that are higher in protein in general also usually do contain more of the special gluten-forming proteins. (I think there may be certain breeds of wheat that are an exception to this rule -- but for the ones that are usually used for standard flour, it's pretty much true.)

So, protein content of flour is an approximate guide to how much gluten it MIGHT possibly form, under the right conditions. But there are complications.

Gluten is made when two proteins in the flour, glutenin and gliadin, link up with each other in the presence of water and agitation. Bleaching and heat treatment must somehow make chemical changes to these proteins. They are still present in the flour (the protein content is the same), but somehow it is harder for them to join up to form gluten (so the gluten-forming potential is lower).

Does that help any, or does it just make everything more confusing?

Here's some information:
http://en.wikipedia.org/wiki/Gluten

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It might be worthwhile finding out if any commercially heat-treated flours are available where you are, Hector. It would be interesting to see how a commercially heat-treated flour compares with a home heat-treated flour ...

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Kate, I've met with my friend Lorraine from Luscious Lorraine (Palm Dessert, California). She is an organic baker and chef, and it was interesting to chat about your discovery. I hope heat treated flour qualifies for organic since I believe bleached flour does not.

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So the idea is that bleaching lowers the protein efficacy and that's good, to a point, but following it up with heat treatment lowers it even more and that's not good?

What about the effects of these treatments on the starches?

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I see. Nothing to do with protein content. But definitely interesting.

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The cake made with heat treated and bleached flour was LOWER than bleached and not treated cake? Is that good?

What is the relationship between protein content and rise? (In my own test the treated flour cake was higher than the untreated flour cake.)

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I can believe that bleaching weakens the gluten. Would heating weaken the gluten? I would guess no, but maybe it could.

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I'm pretty sure that bleaching does NOT reduce the protein content of flour. Neither does heat treatment. (When you cook things the protein does not transform into fats or carbohydrates.)

The manufacturers of flour tend to formulate bleached flours to have less protein (using more soft wheat) because they expect you to use them for cakes and pastries, whereas unbleached flours are expected to be used for bread and are hence formulated to have more protein.

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Adrian wrote:
"Anyway, the conclusion is that the substitution of 1/8 part starch (cornflour) doesn't seem adequate, at least with my flour, to get down to cake flour territory."

Bleaching reduces the protein content of flour ... no? If heat-treatment also reduces the protein content (?), then it wouldn't be a simple calculation on the basis of the % protein before treatment to get down to the level of the protein of cake flour.

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Wasn't Woody already going to be trying that, Rose? ;-)

(I can't find the email where we talked about that right now, but I think I sent you a paper suggesting that bleached cake flour was indeed improved by heat-treatment)

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I think the protein content is a deal - it's just that it's not such a big one ;-)

The first cake I made with microwaved flour - see http://amerrierworld.wordpress.com/2007/10/28/a-question-of-flour/ - was a gigantic improvement on the cakes I made with the same flour, unmicrowaved. The cake I made with the protein content lowered - see http://amerrierworld.wordpress.com/2007/10/30/more-questions-of-flour/ - was better than the cake I made without lowering the protein content ... but not by such a huge amount. I can see what you're saying, though ... why would I ask you to repeat the yellow butter cake, lowering the protein content? It's just that I don't have access to the flours you are using - I tend to find that lowering the protein content makes a more significant difference when the flour I'm using is a mix of soft and hard wheats and is not finely milled (ie UK plain flour rather than 00 Grade flour). Perhaps you would notice this too ... ?? I don't know until you try it ;-)

Like Melinda, I've found that the flour doesn't brown if you microwave it in short bursts, stirring in between.

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I did my own experiments in the interest of scientific curiosity, as I have no problems getting bleached flour. And I didn't get the same results as many others have. So I wonder why? Did I do something different? Is my flour different?

I did incremental microwaving. I can't remember if I stirred. But I do recall that I took the temperature and it was still well below the target temp and then I put it back in and the next time I took it out the temperature was far above the target temp.

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I did a test flour cake bake for Kate using a flour from Shipton Mill here in England. The gluten protein was 8.5%. I did not do the cornflower substitution.
The cake was absolutely lovely. It would not have been as nice without the microwaving of the flour first.
I found I did not get any burned flour bits if I did incremental microwaving and stirred between blasts. I have made many disaster cakes trying different emergency substitutions for cake flour. Nothing has had the results that the microwave heat treating has produced. You can look at my blog for results of the cakes. It is listed under 'testing 3 flours'.Cheers Adrian.

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If the protein content isn't really a big deal then I shouldn't expect to get different results with reduced protein content.

When I did this before, there were a few places where the flour browned. What happens if you microwave for too long? (I tried not to use the affected flour.)

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You're very right :-) I'm not convinced however that the protein content is actually the major contributing factor in the success of this flour. I suspect that more is going on in the microwave than meets the eye. I tried to persuade someone with an electron microscope to have a peek down it at some microwaved flour for me, but the cost was prohibitive. There's a paper by some scientists in Japan (I'll look up the details later) that shows electron-microscope photos of starch molecules in maize after microwaving. The effect is stunning! - the surface of the starch molecules has deep potholes after microwaving.
I haven't tried microwaving the cornflour too ... sounds like a good next move to me :-)

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That definitely sounds like it could take up some time. (So, how much can you raise with a bake sale where the products are all baked in slightly different ways, some with one kind of flour, some with another....:)

I could see where you came from in formulating your substitution. It just seemed to me like a misguided approach because first of all, it assumes that the substitution of 1/8 cup of cornflour actually had any justification behind it. My guess is that it didn't, really. So trying to figure out how to "exactly" replicate this substitution in weight when there was nothing exact to start with seems kind of pointless.

Protein contents are calculated on a per mass basis. I found a claim that gold medal flour is 10.5% protein, and King Arthur 11.7%. (There was no indication of whether the bleached and unbleached gold medal are different.)

If you use a substitition of 3.5 oz flour and 0.5 oz of starch and you start with something that is 10.5% protein the result will be 9.2% protein. (This is 10.5 x 7/8.) If we want to get from 10.5% down to 8% then we need to use twice as much starch (3 oz flour + 1 oz starch). (And you can calculate the protein content as 10.5 x 3/4). And somebody who was using King Arthur would need to use even more starch (about 1/3), so it would be 2.75 oz flour and 1.25 oz starch. (The protein content would be 11.7 x 2/3.)

Anyway, the conclusion is that the substitution of 1/8 part starch (cornflour) doesn't seem adequate, at least with my flour, to get down to cake flour territory. Is there some reason not to use a mix that is 25% starch?

Lastly, if the value of microwaving the flour is that it alters the starch, surely the benefit will be increased if that extra starch is in the microwave with the flour.

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Hi Adrian - Sorry I haven't got back to you before now - I've just taken over as Chair of our local Pre-School and have found myself with not only the regular Chair duties to perform but also with initiating and co-ordinating a community effort to raise £200,000 for a new Pre-School building!

About the weight/volume thing - when I first tried to formulate a way of reducing the protein content with cornflour, I only had as a guide the American "Substitute 1/8 cup flour with 1/8 cup cornflour". However, I wanted to be more precise, especially when it came to involving different people around the world in testing the flour. The problem as I saw it then was that there was no standard weight for a cup of flour, so I couldn't simply convert the volume instructions into weight instructions. The only way I could think of finding out what a cup of flour weighed for each specific flour after microwaving was to actually get a cup, fill it with flour and then weigh that flour. Hence my rather convoluted instructions.

However, after further discussion with Rose, I understand that the 7:1 flour/cornflour ratio can equally apply to weight (remember that I had only seen this before expressed as volume). So (and I mean to update this on my blog, too), I now microwave my flour then make it up into parts of 3 1/2 oz flour + 1/2 oz cornflour - no cups involved :-)

Does that help explain my ideas any? (PS - I confess, I'm not a natural mathematician ;-) !).

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I was under the impression that baking by volume was an American practice and that in Europe everybody baked by weight. Am I mistaken? The text on her blog is written as if you're going to bake by weight.

(I wrote to Kate about the substitution, but haven't heard back.)

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Does that mean it would make sense to add some cream of tartar to the flour to acidify it? (Or to increase acid in the recipe some other way?)

Of course I will use weight. The plan is to make the downy yellow butter cake from the cake bible with kate flour that has been protein adjusted and with unbleached flour that has been protein adjusted but not microwaved. (Hmmm. Maybe I need a 3rd cake made with unmodified unbleached flour too...?)

Kate's procedure on her blog seems a little overcomplicated. She says to "[S]ubstitute 2 tablespoons of this cup with 2 tablespoons of cornflour/cornstarch. Do this by calculating and then removing 1/8 of the weight of the cup of flour. Replace this with 1/2 oz (14g) of cornflour." It seems that she cooks by weight but makes this diversion into volume measurement to calculate the starch replacement.

It seems more sensible to me to simply take the desired weight of flour and replace 20% of it by weight with starch. I suppose for best results this should be done before microwaving, though I'm not sure I want to bother with that.

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Well, if I'm trying to drop from 10% to 8% I should use 80% flour and 20% starch which is a bit more than the recommended amount, but not so extreme.

Is chlorine bleaching better simply because it's harsher and damages the starches more? I vaguely recall reading that the chlorine treatment left cake flour slightly acidic and that this caused the cake to set faster (hence giving a finer texture).

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I have done two tests with Kate flour, and I posted results to Kate's blog with pictures available.

I made two chocolate chip cookies and noticed that the pillsbury bleached flour and the kate flour didn't brown as quickly, and the unbleached ones may have spready slightly more, but differences were fairly subtle. This is in contrast to Kate's results which showed a significant improvement in the cookies from the treated flour.

For the cakes I made two cakes and coming out of the oven there was an obvious difference: the unbleached flour cake fell in the center. But when it came time to eat the cakes the difference was again fairly subtle. I couldn't really pick a favorite.

Kate asked me to repeat the tests with the same cookie recipe she used and with the gold medal unbleached flour adjusted for protein content.

But at this point, I get confused. Kate thought that the gold medal unbleached flour was 10% protein and the cake flour 6% protein. If that is true, I calculated how much starch to add in order to reduce the protein content from 10% to 6% and it's a huge amount, not the paltry 1/8 cup per cup that is often advised. Instead, I need to use something like 55% flour and 45% starch. I don't think I've ever seen a ratio like that recommended.

I also have another point of confusion. I thought that only cake flour was chlorine bleached and other bleached flour was bleached with peroxide or some other agent. I also got the impression that the chlorine bleaching had a different effect that was particularly important for cakes. Is this true?

Is the difference in my cookies due to protein content or due to the treatment (bleaching/heating)?

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thanks much kate, i've heated up another batch of flour and i'll try again tomorrow.

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Here are the steps, aisha (and anyone else, for clarification). I found that the temperature thing was very important - in fact, as I hope you too will find aisha, it made the whole difference to the success (or otherwise) of the flour ...

Turning Unbleached Flour into Kate Flour: 10 Steps

1. Weigh out 280g/10 oz of the flour and place it onto a microwave-safe plate.
2. Spread the flour on the plate to give a bed depth of 18 to 20 mm.
3. Microwave the flour for 1 minute. Remove from the microwave and use a probe thermometer to take and record a temperature reading. Break up any lumps with a fork.
4. Repeat step 3 until you obtain a temperature reading of at least 130 degrees C.
5. Allow the flour to cool to room temperature.
6. Sieve the flour and discard any residue.
7. Spoon the flour into a 250ml measuring cup and level the top. Weigh this flour and record the weight.
8. For flours with a 9% or more protein content and when cake flour is required, substitute 2 tablespoons of this cup with 2 tablespoons of cornflour/cornstarch. Do this by calculating and then removing 1/8 of the weight of the cup of flour. Replace this with 1/2 oz (14g) of cornflour.
9. Make up a second part of kate flour according to the weights of flour and cornflour obtained in steps 7 and 8.
10. Place both parts of kate flour in a large bowl and whisk to combine thoroughly.

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aah, i went back to kate's site and saw the helpful hint about measure the flour's temp. i wish i had been more thorough in my background reading. well, i'll give it another shot in a few days.

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well, the results are a bit disappointing. there's no real difference! both came out about 1.25 inches. and stayed that way. i want to say the heated flour's crumb was a little finer, but barely. i had heated 4 oz of flour 3 times, for 1 minute each.... maybe i should have done it a little longer. i never saw any vapor, though the flour did clump a bit.

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I've just put in a pair of 9 inch cakes in the oven, one with treated unbleached AP flour, the other untreated. *fingers crossed*

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I'd guess yes, it would work. It would be great if you could try it and let us know :-)

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I just came across this via a post at Daring Bakers. I've been using Gold Medal unbleached AP for all baking because I wanted to avoid the chemicals, and I guess this is why my cakes were never as light as I would like. They weren't lumpy or chewy, just dense. My question is, can I do the Kate treatment on the Gold Medal unbleached i buy?

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I am trying to make Russian Rye Bread. My bread turns out very heavy and dry. Need Help. So you have a receipe. Sandy

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well, the "problem" thing may be relative and vary from person to person. even with Rose's recipe for Genoise Classique or French Genoise i once got such a crumbly output .
http://www.apona-bd.com/photos/rcache/c20b9c6d476f0328cc92eed8d6529ff0.jpg
chosing a lower-protien flour and then switching to Kate Flour has changed the result. hope to post a better-result-photo later this month.

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I use unbleached flour all the time for all my baking needs and have never had a problem with it. I won't use bleached flour, since that's just what it is, bleached, with chlorine.

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From a safety point of view, I really wouldn't try microwaving any more than about 10 oz of flour at one go. It gets very hot! (plus, it would make the bed deeper than 2cms ... unless you have a super-large microwave, of course!).

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Thanks, Rose.

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Hi Kate/Rose- can i make Kate-flour(in bulk) now and use later, or is it necessary to process the flour immediately before baking?

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I am trying to make pastry type crust for samosas and the unbleached AP Flour wont solidify...stays crumbly..whats the problem?

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i wanted to let you know that the kate flour worked brilliantly for me. in fact it has stopped me giving my copy of the cake bible to a charity shop. it was a gift from friends in the states and everything i tried was disappointing so i was about to give it away. only last week i made the domingo cake, it was solid. today i followed the directions on kate's blog to make kate flour. the same flour, a totally transformed cake!!! it's incredible.

Rose, without overstating the point, isn't this something fairly huge for you, i mean your book now has viable sales outside the states? will you include kate flour in your next book or is it too late for that?

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Rose, thanks for the help, and for pointing me to your crossing the Atlantic post.

What I'm getting from this is that bleached flour will generally make a lighter product then unbleached. Therefore, if you want a denser bread, you would go with unbleached bread flour, which would also have the benefit of having more gluten to strengthen the bread's structure.

If using bleached bread flour (I can't recall if I've seen this; I think I have), you would need to add more flour or some vital wheat gluten to compensate for the gluten loss from bleaching.

This also explains why I don't ever find unbleached cake flour.

This raises the question of what makes better pastry flour; I'll have to experiment with pastry flour made using bleached AP vs unbleached AP mixed in with the cake flour (I seem to have a hard time coming by pastry flour).

Thanks again; that helped a lot.

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I have two quick questions:

1) How does bleaching allow the flour to gelatanize?

2) Is there a good rule on when you want bleached flour and when you want unbleached?

3) In bleached flour, it would seem like you're eating some bleach. That sounds unhealthy. Are we eating any bleach from this, and if not, why not?

4) Does anyone have any tips on how long to cook a frozen pie vs. a normal one? My parents made a bunch of apple pies for Thanksgiving and froze them, and don't know what the best method of cooking them would be.

Thanks for the help.

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Now there's some daylight again, I've added a photo to the above blog post to illustrate the results :-)

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If you have a thermometer, this approach seemed to work well today and is easier than guessing blind at microwave times and powers ...

http://amerrierworld.wordpress.com/2007/11/10/getting-warm/

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From what I understand about it, yes, but it would take a substantially longer time (I've read of this being done for 10 hours to 2 weeks!). Perhaps the microwave will become the new KitchenAid (or Kenwood, for those of us in the UK)!

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If one doesn't have a microwave, would it be possible to achieve similar results by, for example, baking the flour in a warm oven?

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Yes, this is something I've been thinking about recently. My microwave is 750W, so 'high' for me is quite a bit less than 'high' for others. I'm hoping to be able to present some clear guidelines after testing which will include a breakdown of how many minutes to microwave the flour at different levels of W (750/850/950 etc). It would be helpful to get a rough idea for now of the sorts of W that people typically have (I use my microwave mainly to defrost baby purees I've prepared and frozen, so I'm not really your 'typical' microwave user!)

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Yes, this is something I've been thinking about recently. My microwave is 750W, so 'high' for me is quite a bit less than 'high' for others. I'm hoping to be able to present some clear guidelines after testing which will include a breakdown of how many minutes to microwave the flour at different levels of W (750/850/950 etc). It would be helpful to get a rough idea for now of the sorts of W that people typically have (I use my microwave mainly to defrost baby purees I've prepared and frozen, so I'm not really your 'typical' microwave user!)

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I have a high power microwave also. I put the flour in for 1.5 mins. , take it out and stir it about a bit then put it back in for another 1.5 mins. It is best to put in more flour than the recipe says as you lose some weight with the moisture lost, and you also do get the flour lumping together so it needs sieving well . I f this does not help try lower power or less time , say 30 secs. less to see if that helps. I have made one very successful cake using microwaved flour, the one I made last had a nice texture but didn't rise as much as I would have liked. I'm wondering about the differences in baking powder between the countries also, could this affect results?

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I have tried microwave the flour. My microwave is 900W and after 2 minutes on the highest power, the flour seemed to be cooked,some sticking to the bottom of the pyrex plate and get into large lumps. I have to sift it and a lot cannot pass through and I have to add more flour to the required amount.Is that so ? or should I use lower power?

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I hope you don't mind me posting this here too, as well as on my own blog, Rose. There has been the suggestion of creating a clear formula for bakers to follow, including flour type, quantities, etc. I think this would be an excellent next step.

Perhaps we could have a co-ordinated, international testing effort as many flours will be specific to different countries …

If anyone is interested in taking part in something like this (or has a better idea or even experience in developing baking formulae), perhaps you could send me an email - amerrierworld at googlemail dot com - thanks

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A v. interesting comment has just been posted to my blog re improved texture results after microwaving even cake flour (see comments on my latest post). Is this something that anyone else has tried (or would someone with access to cake flour be willing to try this for me ...?)?

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Yes, she does! It is a very big deal to us here in the UK, who can't get access to any bleached flour.
Her results are fantastic!

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