When it comes to baking sourdough bread, or anything with flour, it's not just about the starter or the technique. The flour you select is a pivotal factor, shaping the taste, texture, & nutritional content of your food, making it an important decision for any recipe.
In this article, I'll dive into the differences between roller-milled & stone-milled flour, explore the nutritional benefits of both, & provide some key considerations for selecting the best flour for your sourdough creations (or any baked goods for that matter)!
But first, the anatomy of a grain:
Understanding the parts of grain helps paint the picture as to why the quality of flour is so different with each milling method. Essentially, grains are a seed (also known as a kernel) made up of 3 parts: the bran, germ, & endosperm, all of which are protected by a layer called the husk which is an inedible part of the plant but an important fighter against pests, sun damage, water, & diseases.
The layers of grain:
The Husk: The outermost layer that's not typically consumed. Its role is to protect the kernel from damage.
The Bran: The layer directly beneath the husk. It's completely edible & contains important B vitamins, antioxidants, & fiber.
The Germ: Considered the embryo of the grain, this is the part that would sprout & grow into a new plant if you were to let it. It also holds most of the grain's nutrients, including essential fatty acids (yes, grains have fat!), vitamins, minerals, & proteins. Because of these nutrients, it adds a beautiful flavor & nutritional profile to grains. The Endosperm: This is the part of the grain that supplies food to the germ. It's the largest part of the kernel containing mostly starchy carbohydrates, some proteins, & a few vitamins & minerals. Essentially, it's the grain's life source, providing energy to the plant so it can continue to grow.
So, how does a kernel of grain become flour?
Through the process of milling! Which is essentially grinding the kernels down into a thousand tiny, sandy particles. Generally speaking, the process is pretty straightforward. But the end result can look, feel, & taste drastically different depending on the type of milling technique that was used.
A deeper dive into milling:
Some of the earliest tools to mill grains were stones, large rocks, & pestles. They were used to crush & grind kernels, creating a very coarse flour, one that would feel much grainier than what we see today. This process has since evolved into a modern version of what we now call stone milling.
Around the late 18th century, the milling industry dramatically changed with the invention of the roller mill - a type of machinery with a series of rollers that grain passes through to separate the endosperm from the bran & germ, leaving behind a white, fine, starchy flour. This not only created a softer, more palatable flour, but more importantly, it sped up the processing time which made for an efficient way to produce larger quantities of flour. This was especially useful during a time when flour was in high demand worldwide.
A side-by-side comparison: Roller-milled vs. stone-milled
Before jumping in, I'd like to note that there are other ways to mill flours, but these are two of the most common techniques used today.
Roller-milled flour: As I mentioned, this type of milling is fast & predictable. Because of that, it's almost always used for commercial flour production where the primary goal is to create as much flour as quickly & inexpensively as possible. During this processing, the grain is cracked open & the endosperm is isolated from the bran & the germ. And what do we remember about the endosperm? It's essentially starch. This creates a beautifully soft & tender product with a very long shelf life but it lacks in flavor & has lost most of the grain's nutrients. Roller milling also generates a lot of heat, which further degrades vitamins, minerals, & helpful enzymes.
Production: Roller-milled flour is the result of industrial milling processes that use steel rollers to crush grains into fine powders.
Consistency: Roller-milled flour tends to be uniform in texture & is often preferred for commercial baking due to its predictable results.
Nutrition: While roller-milled flour does retain a few nutrients, it generates a lot of heat during the process, so some heat-sensitive vitamins & enzymes may be lost while undergoing high-speed milling practices.
Stone-milled flour: A more traditional method of milling grain, this process involves grinding grain between two large, flat stones. The bottom stone, known as the bedstone, is stationary while the top stone, called the runner, rotates circularly above it. Grains are fed through the center & are then pushed outwards toward the edges as they're milled down. This process is slow but gentle, resulting in less heat damage which preserves the bran, germ, & endosperm, creating a more nutritious flour. The flour often has a coarser texture & heartier flavor because the natural oils are retained but with that, its shelf life is not as long.
Production: Stone-milled flour, as the name suggests, is milled using stones, preserving the integrity of the grain's components.
Texture: Stone-milled flour can have a slightly coarser texture, which some bakers appreciate for the rustic character it imparts to bread.
Nutrition: Stone-milled flour often retains more of the grain's natural nutrients, including fiber, minerals, and certain enzymes, making it a popular choice among artisanal & health-conscious bakers.
Personally, I prefer stone-milled flours over roller-milled. As a nutritionist, nutrient quality is of course important to me, but I also appreciate the traditional way of creating foods. Stone milling takes us back to a time when producing flour wasn't just about efficiency, but instead, emphasized the preservation of grains & their nutrients as a whole. And I'd be remiss to not mention the physical differences... taste, texture, & colors are all heightened, producing a rustic, artisanal loaf of bread that I think nearly everyone would prefer ;)
Finding stone-milled flour:
If you're interested in trying stone-milled flour for yourself, I always recommend looking locally. Depending on where you're at, you may be able to find a local miller selling stone ground flour, or a farmer at your neighborhood market. I'm pretty lucky to live in an area with many choices to choose from. One of those is Carinspring Mills, a company based out of Skagit Valley here in Washington with beautiful stone-milled flours using locally harvested grain. Their flour is nutrient-rich & creates a dark, rustic loaf. I've been baking with their flours almost exclusively since 2020 & they were kind enough to get me a discount code for you! If you'd like to try, use code MCKENNA15 & take 15% off your next purchase. PS - they ship nationally!
What to consider before buying your next bag of flour:
As you navigate the world of flour, whether it's for making bread or the occasional weekend bake, here are a few things to keep in mind as you look for flour. For a lengthier list, check out my top 8 things to think about before you head to the store...
Flour Type: Different flours (e.g., all-purpose, bread, whole wheat) yield different results in sourdough or any baked good for that matter. All-purpose has the lowest protein content which will make it softer, not as hearty. Whole wheat on the other hand has a higher protein content, resulting in a darker color, with more flavor but denser crumb. Experiment with various types to discover your favorite flavor & texture.
Milling Method: If you're after the health benefits & nuanced flavors of stone-milled flour, seek out companies that specialize in this traditional milling process.
Freshness: Whenever possible, choose flour that's as fresh as possible. Whole grains can go rancid over time, affecting the flavor and quality of your bread, this is especially important to consider if you're buying stone-milled flour. Some local companies will put the mill date on the bag, so it's worth double-checking.
Locally Grown: Whenever possible, I encourage sourcing locally grown & milled flour. This supports local producers & reduces the environmental footprint of your ingredients. I'd take this a step further & say get to know your farmer. Ask questions about their growing practices, who mills the flour, etc. It's a neat opportunity we have to get to know where our food comes from & exactly how it ended up in your hands.
Final thoughts
Today, stone milling is typically used by artisanal & specialty millers who value its ability to produce high-quality, nutrient-rich flour with distinctive flavors. It often comes at a higher price, but whenever it's possible, I personally find it's worth the extra penny. Baking is a personal journey. Trust your taste buds & preferences. Try different flours from different companies & you'll soon find the one that resonates with your palate.
Looking to start your sourdough journey?
I created a FREE guide with everything I wish I knew when I grew my first starter. Here's a step-by-step guide with printable pages, recipes, timelines, troubleshooting, & more!
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