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Flour is the most important component in bread. However, as bakers, we often don’t know much about the processes involved in making it. The growing interest in home milling and heritage grains is making milling more visible, but many aspects of a miller’s craft remain a mystery. To get a better picture of what milling consists of, I contacted two millers in South Australia, whose flours I regularly use with great results, Laucke Flour Mills and Four Leaf Milling. Both agreed to meet me, happy to share their knowledge.

Laucke Flour Mills is a family-run company that has been operating in South Australia for over a century and currently has its third generation at the helm. Ensconced in the mill’s baking test lab, I had a fascinating conversation on baking and milling with Martin McLennan. Four Leaf Milling was founded by Rosemary and Gavin Dunn who have been milling organic flour since the 1960s. They are now grooming the younger generation to step in to uphold the tradition of their milling principles.

Four Leaf Milling is a certified producer and miller of organic grains. Laucke Flour Mills processes both organic and conventional grain, with an objective to process both as “cleanly as possible” with the minimum amount of pesticides applied to the harvested grain.2

Both mills have an extensive offering of flour varieties ranging from wheat to the increasingly popular ancient grain types such as spelt.

Differences Between Roller-Milled and Stone-Ground Flours

Milling is the process of breaking wheat kernels into small particles that are refined to various degrees, that is, flour. The method used for doing this is the most notable difference between the two millers: Laucke Flour Mills primarily roller mills the grain while Four Leaf Milling only produces stone-ground flour.

Many people prefer stone-ground flour because they believe it has a higher nutritional content and a better flavor.

Roller milling is the conventional method of milling: the grain is milled using steel rollers and then pushed through consecutive sets of sieves that separate the bran from the endosperm. The process results in a soft, white, refined flour that consists mostly of endosperm—desired by many over the centuries. To make wholemeal flour, millers put a certain percentage of the sifted-out bran back after the initial milling.

In stone milling, the different parts of the grain do not get separated but are crushed and distributed together using a pair of millstones. Four Leaf Milling processes the grain through a stone grinder, and all that comes out is used. Compared to roller milling, the temperature of the flour stays cooler, which helps maintain higher protein levels and does not disrupt essential enzyme activity. Many people prefer stone-ground flour because they believe it has a higher nutritional content and a better flavor.

When comparing flours, bakers and millers often talk about extraction rates.

Millstones at Four Leaf Milling.

Millstones at Four Leaf Milling.

According to Martin McLennan, “The extraction rate is the percentage of the whole grain that remains in the flour.”

So, wholemeal flour should have a 100% extraction rate because it contains all of the bran. In roller milling, this is not strictly true because the bran is added back after the sifting process—whether this was the content of bran found in the initial milling is debatable.

The extraction rate is also a measure of the mill’s efficiency: when making white flour, a good mill can reach an extraction rate of 78-79%. If the number is lower than that, there was either more bran in the milled grain or the endosperm was poorly sifted and got stuck in the bran.

Spelt differs in the sense that, unlike normal wheat, it is harvested with its husk still on it. The husk in spelt needs to be removed while it still has the bran on it and, as a consequence, there is less bran to be found in spelt flour than in wheat flour.

Moisture Content in Milling

To get the best out of the grain, millers need to know and control its moisture level. This is done by grinding a wheat sample.

At Laucke Flour Mills, where most of the milling is done using roller mills, the aim is to achieve a moisture content of around 13.8%. By going for a reasonable amount of moisture penetration on the bran but not so much on the endosperm, they hope to make the grain like a pea popping out of the pod. Ideally, as soon as the bran goes through the first break rollers, the endosperm would shoot out leaving a big lump of bran behind. It doesn’t usually happen, but it is the aim.

Moisture meter.

Moisture meter.

The measurement is done by grinding a wheat sample which is then placed in a chamber that will measure how much moisture there is in it (using sophisticated infrared technology). Based on the results, some amount of water is added to the grains by storing them up to 48 hours in large conditioning bins before they go through the mill. Hard wheat usually needs more conditioning than soft wheat.

At Four Leaf Milling, moisture content (they aim for 12%) is measured using a moisture meter, and for a different purpose: all grain loads that come to the mill are tested, to make sure that they are safe for storage. If grain were to be stored above a moisture level of 12%, they believe this would invite mold problems.

Protein Content in Flour

One of the things bakers often focus on when considering the flour they use is its protein content, ”Too much so,” Martin McLennan suggested, “unless you want to make a rubber ball. And adding gluten is unnecessary.”

The general school of thought is that high protein flour is better suited to bread making.

The general school of thought is that high protein flour is better suited to bread making. However, Martin disagrees. He believes that the wheat variety is more significant when it comes to making bread. Within one wheat variety, protein content can be anything between 10% and 14%. A protein content of 11% is good enough for general bread such as French baguettes—anything higher than that would only be too tough and chewy. The one instance where a higher protein content is desirable is when making bagels, which are expected to be dense and chewy.

Weather conditions also affect the protein content and the quality of the flour. Water dilutes the nitrogen in the soil, which in return diminishes the protein content in the grain. In a nutshell: wet weather leads to low protein and dry weather to high protein flour. Because of the wet weather this past season, both millers expect all flours to be softer this year.

As wheat needs to be dry to ripen properly, the wet season also delayed harvests. Farmers in South Australia harvest only once a year, usually starting around November. This year, they were still harvesting in January!

Grain classification in Australia is less complex than in the United States. Its purpose is to determine whether the grain is suitable for human consumption in the first place, and secondarily, to assign a benchmark for the grain’s hardness, color, and protein content to assist in determining whether the flour is suitable for bread making or pastry making.

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