Milling
Transforming wheat to flour
Commercial wheat mills in Canada have been processing wheat into flour for over 200 years. Today, about 55 commercial wheat and oat mills operate from coast to coast.
Mills can have wheat delivered directly from the farm to their operation but this is limited. Typically, most wheat arrives from grain elevators where it has been stored. Grain elevators are found throughout Canada and is where farmers deliver their grains for domestic or global sales.
Milling process
‘Milling’ is the term used to describe the process of grinding or crushing grain kernels into flour or semolina so they can be used to make food.
Canadian mills use state-of-the-art milling equipment and technology, but it’s important to recognize that even through hundreds of years, milling remains a simple, mechanical process that transforms wheat kernels into various kinds of flours. This involves rolling, grinding and sifting into the component parts of bran, germ and endosperm. Different wheat flours are made from a ratio of these parts, and have different applications. The most common are whole grain whole wheat, whole wheat flour, and white enriched wheat flour, known as all-purpose flour. See Wheat Basics for a description of the parts of a wheat kernel and a list of flours produced in Canada.
Wheat and wheat flour in Canada are produced by a team of experts, from research scientists and farmers, to grain handlers and millers, who follow stringent protocols that ensure food safety and quality.
Preparation for milling
Each truck- and train-load of wheat delivered to the mill is tested to determine the protein and moisture levels as well as test weight. A high test weight is one indication of milling performance which includes how much flour that load of wheat will yield.
The wheat is also tested for food safety and checked for non-wheat material, including insects and other grain. Once all testing and quality control is complete, the kernels are ready to mill.
Flour milling
After the wheat is cleaned free of impurities, it is tempered. Tempering is the process of adding water to wheat to soften the outer layer of the bran. After it has been tempered, the kernels will rest in bins for up to 24 hours to condition in preparation for milling.
Most wheat milling capacity in Canada relied upon various designs of stone milling until the late 1800s, but the revolutionary technology that modernized wheat milling is known as the ‘roller mill’ or ‘roll stand’.
A roller mill ‘breaks’ the wheat kernels by passing it between two metal rolls, tightly spaced together and rotating in opposite directions. The ground pieces of the wheat kernels are returned through a series of pairs of rolls until the entire wheat kernel is ground to a consistency sufficiently fine to enable separating by sifting (bolting) and air current separation (purifying) to make flours of differing coarseness or particle sizes.
Flour Conditioning
Once milled, some flours are fortified with enrichment and/or treated with additives or enzymes to enhance appearance and improve functionality.
What is refined wheat flour?
Refined wheat flour is popular in Canada and around the world, and is used to make many different products like baked products, noodles and pasta. Many people also use this in their home baking. Refined wheat flour stays fresh longer and is also great for non-baking applications like thickening gravies and sauces.
Seventy percent of the flour produced in Canada is refined wheat flour, containing only the endosperm portion of the wheat kernel. While all parts of the kernel have nutritional value, when removing the bran and the germ, some of the nutritional value is reduced. By legislation in Canada, refined wheat flour must be enriched with vitamins and minerals to replace these nutrients lost (or removed) during the milling process. Enrichment usually involves the addition of vitamins and minerals in powder form. Mandatory nutrients include thiamine, riboflavin, niacin, folic acid and iron. See Enrichment and Fortification for more information.
Flour naturally whitens as it ages and is exposed to oxygen. However, this process takes a few weeks, requiring storage and the possibility of contamination. To speed up this process, some millers may add flour conditioners that create finer textures and improve baking quality. This is often referred to as ‘bleaching’.
Capacities of most flour mills vary from 50 to 2,000 tonnes of wheat per day, although there are mills of higher or lower capacity. A flour mill may produce only one type, or as many as 50 types of flour.
Did you know?
Some of Canada’s largest modern grain mills are operating at or near locations where mills have operated for more than 100 years.
Wheat travels near and far
A small number of grain farms are located close enough to wheat mills to make it practical to deliver wheat directly from the farm to the mill. Most wheat moves to market by truck or railway cars to arrive at mills in other regions or to port facilities for loading onto ships. Canada’s grain handling and transportation system covers thousands of kilometres, extending from inland grain-producing regions to both the Pacific and Atlantic coast ports of Vancouver, Prince Rupert and Halifax, as well as terminal elevators located around the Great Lakes and Lower St. Lawrence River.