Transforming wheat to flour
Commercial grain mills in Canada have been turning wheat into flour for over 200 years. Today, about 55 commercial wheat and oat mills operate from coast to coast.
A very small portion of Canada’s wheat crop is delivered directly from farm to the mill; most wheat arrives from a grain elevator where it has been stored after harvest.
‘Milling’ is the term used to describe the process of grinding or crushing grain kernels to make them suitable for cooking and consumption.
Canadian mills use state-of-the-art milling methods 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 101 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 truckload 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 an indication of how much flour it 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.
After the wheat is cleaned free of impurities, it is tempered (i.e., water is added to soften the outer layer of bran on the wheat) and rests in temper 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 by passing it between two metal rollers, tightly spaced together and rotating in opposite directions. The crushed pieces of the wheat kernels are recycled through a series of pairs of rolls (first, second and third break) until the entire wheat kernel is crushed 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.
Once milled, some flours are conditioned to achieve enrichment, enhance appearance and improve functionality.
Refined wheat flour is highly demanded in Canada and around the world for its versatility. It’s a flour that’s easier to bake with, stays fresher longer and has great non-baking applications (e.g., for thickening gravies and stews).
Seventy percent of 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 losses. 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 several months, requiring storage and the possibility of contamination. To speed up this process, millers 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 farm to mill. Most wheat moves to market by truck or railway cars to get to 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.