For this week's "I really should know more about…" mini research project, I'll be taking a somewhat in-depth look at a breadmaking technique that's enjoying a bit of a revival in the world of sourdough baking - the autolyse.
AUTOLYSIS n. the breakdown of plant or animal tissue by the action of enzymes contained in the tissue affected; self-digestion.
WHAT IS IT: DEFINING AUTOLYSIS
While biologically speaking the term 'autolysis' is fairly self-explanatory—the destruction of a cell through the action of its own enzymes—when it comes to baking bread, the autolyse is best described as the period of rest that follows the initial mixing of two of a dough's most basic ingredients, its flour and water. This technique was first championed by Raymond Cavel, a Professor of baking at the National Graduate School of Milling and Cereal Industries (ENSMIC) in Paris, France. Not only was Prof. Cavel credited with leading the revival of French-style breadmaking during the mid-1900's, he also went on to produce and extensive body of research on the subject. The method for an autolysed dough is appreciably simple; flour and water are mixed at low speed and then allowed a period of rest (anything from 30 minutes to being left overnight) before the salt and then levain are added and the mixing and kneading is completed. The reason to use such a technique is because it is thought that by allowing the dough to relax before kneading has fully developed the gluten it will become more extensible, and therefore easier to shape.
HOW DOES IT WORK: A LOOK AT DOUGH STRUCTURE
If you've ever tried making bread that is gluten-free you'll appreciate that one of the unique properties that sets wheat flours apart from other cereals and grains is its ability to create doughs with cohesive, lively qualities that transform what begins as a wet, floury mess into a smooth and taut self-supporting loaf. While a number of factors influence this process—kneading technique, the type of flour used, the percentage hydration, and the presence of salt, sugar, fats, acids and oxidising agents to name but a few—for the purpose of understanding more about the autolyse I'm going to focus on three of the key components: gluten, starch and gas.
- GLUTEN: Gluten is a complex mix of wheat proteins that make up approximately 10% of a flours weight. While they are hydrophobic, and therefore insoluble in water, these proteins are still able to interact with the water molecules, which confers the capacity to change shape, create (and break) protein-protein bonds, and allows them to move relative to each other. By forming both weak and tight bonds between the various proteins (gliadin and glutenin, respectively), this allows the gluten to establish an extensive, interconnected network that provides both plasticity and elasticity to the dough, enabling it to not only change shape under pressure, but also to move back towards its original shape once the pressure is removed. Put another way, what this means is that as it bakes the dough is able to expand to accommodate any gas bubbles produced (plasticity), while still having sufficient resistance to prevent the air pocket walls from becoming too thin and breaking (elasticity).
- STARCH: Starch granules makes up 70% of a flours weight, and also exert strong influence over this network. They provide bulk, in making up more than half of the volume of the dough, and like gluten also hold water to their surface, which allows them to penetrate and tenderise the protein scaffold. When heat is applied the water on the surface of each granule is absorbed, causing the starch to swell and set so that the walls that surround any gas bubbles present become rigid. By stopping the expansion of the gas, this in turn works to force the water vapour being generated to pop the bubbles and escape, resulting in a continuous network of interconnected holes, or what bakers refer to as the crumb of the bread. The ability of a dough to establish this spongey network is critical because if the water vapour is unable to escape, then it will condense as the loaf cools and cause the bread to collapse.
- GAS: Carbon dioxide produced by yeasts or chemical leavening agents influences dough structure by interrupting and weakening the network formed by the gluten and starch granules. This interruption serves to divide the network into millions of thin, delicate sheets that go on to become the air pocket walls. While somewhat of an aside, it's worth noting that yeasts and chemical leavenings don't actually create new bubbles—the carbon dioxide they produce is released into the liquid phase of the dough and simply diffuses to enlarge whatever tiny bubbles are already there—so the initial aeration of the dough will strongly influence the final texture of your loaf.
WHY USE IT: THE AFFECTS ON YOUR LOAF
Because the role of the autolyse is primarily in influencing dough structure, the main difference you'll notice is in the handling as doughs made using an autolyse are purportedly more extensible and easier to shape. The resulting loaves are said to have more volume and a better crumb structure than those made with extended kneading, and should also appear lighter as there is less oxidation of the flour (and better retention of the creamy carotenoid pigments) due to the shorter mixing time. Lastly, as the length of time for the autolyse increases there is also a greater availability of sugars due to the action of enzymes (mostly amylases) present within the flour. Not only will this provide a noticeable sweetness to the bread, but the crusts on doughs made using a long autolyse should also caramelise to a deeper golden hue.
- McGee, H. (2004) On food and cooking: The science and lore of the kitchen (revised edition). Scribner, New York, New York, USA. ISBN 978-0-684-80001-1.
- Reinhart, P. (2001) The bread baker's apprentice. Ten Speed Press, Berkeley, California, USA. ISBN 978-158008-268-6.
- Robertson, C. (2010) Tartine bread. Chronicle Books LLC, San Francisco, California, USA. ISBN 978-0-8118-7041-2.
- Robertson, C. (2013) Tartine book no.3. Chronicle Books LLC, San Francisco, California, USA. ISBN 978-1-4521-1430-9).
- Wing D, Scott A. (1999) The bread builders: Hearth loaves and masonry ovens. Chelsea Green Publishing Company. White River Junction, Vermont, USA. ISBN 1-890132-05-5.
** The loaves pictured in this post were from work where, at the time of writing, we were making our white sourdough loaves using an approximately 18-hour autolyse.