Update May 2012: Heat-treated flour is now being sold to home bakers in the UK!
See: Boom Boom Ain’t It Great To Be Floury.
From Cake Flour to Kate Flour
Kate flour has been created as a replacement for bleached flour in countries where the bleaching of flour is prohibited. In these places, which include the countries of Australasia and the EU, bakeries and other businesses may have the opportunity to source heat-treated flour as a viable and successful alternative to bleached flour for use in high-ratio cake recipes. The home-baker is not so lucky.
Until commercial, heat-treated flour is made available to the individual consumer for personal use, kate flour is perhaps the sole means by which home-bakers in these countries can recreate and appreciate the advantageous properties of bleached flour in their own kitchen.
The Story of Kate Flour
The creation and development of kate flour can be followed in the following blog posts from Autumn, 2007:
A Question of Flour, in which the microwaving of flour was introduced;
More Questions of Flour, in which the protein content was cut;
Water, Water Everywhere, in which the moisture content was considered;
Getting Warm, in which the thermometer made its first appearance;
… with additional refinements in Spring, 2008:
Finding the X Factor, in which xanthan gum improves the viscosity;
Colour or Crumb, where self-raising flour provided the best-yet results;
… and even further refinements in Winter, 2008:
Treatment of Choice, in which the toasting problem is resolved and the conventional oven joins the fun.
Turning Unbleached Flour into Kate Flour: 10 Steps
1. Weigh out 280g/10 oz of the flour and place it in a microwave-safe, flat-bottomed bowl.
2. Spread the flour in the bowl to give a bed depth of 18 to 20 mm.
3. Microwave the flour for 10 seconds then open the door and stir with a fork to prevent the flour from browning. Continue to microwave and stir the flour at 10-second intervals.
4. After about 3 minutes of total microwaving time use a probe thermometer to take and record a temperature reading. Repeat microwaving and stirring at 10-second intervals 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. To re-hydrate the flour, spread it on a baking tray. Place it in a cold oven (with the oven turned off). Pour boiling water into a dish placed on the floor of the oven. Close the oven door and leave for 5 minutes. Replace the water in the bowl with boiling water and leave for a further 5 minutes.
8. For flours with a 9% or more protein content and when cake flour is required, weigh out the amount of flour needed for the recipe and substitute 1/8 of this weight with cornflour.
9. Add 1/4 teaspoon of xanthan gum (1/8 teaspoon for recipes using up to 5 oz flour) to the flour needed for the recipe.
10. Whisk to combine thoroughly.