Why Stone-Ground Flour

A Set of Granite Mill Stones

We chose stone-grinding as our milling method because we are convinced that it provides the most nutritious type of flour. For making Sun Prairie stone-ground flour, whole kernels are ground between two hand-chiselled granite mill stones, similar to those shown above.

100% stone-ground flour contains the whole grain in its original proportions: the Vitamin E rich wheat germ, the outer mineral-rich bran layers and the endosperm. The Canada Food and Drugs Act requires that flour labelled as “Whole Wheat” contain at least 95% of the total weight of the wheat from which it was made. Sun Prairie 100% whole wheat flour is composed of the entire wheat kernel. There are no additives or preservatives in our flour such as synthetic vitamins, bleaching, maturing and dough conditioning agents commonly used in larger commercial flour mills.

To maintain the quality and nutritional value of our flour we take great care to adjust the milling rate so that temperature does not exceed 43C (110F). Heat causes the oil from the germ portion to oxidize and become rancid and much of the vitamins to be destroyed. Since only a small amount of grain is ground at once, the oil from the germ is well distributed which also minimizes spoilage. Nutritive losses due to oxygen exposure are limited by the coarse texture of the flour (Campbell et al., 1991) This article can be viewed at http://www.eap.mcgill.ca/Publications/EAP35.htm

Milling Techniques

Stone-grinding is one of the oldest and simplest ways of making flour. Rotary grind-stones powered by animals were used for grinding grains as early as the third century B.C. Over the centuries, the power source for turning the mill stones has evolved from animals to water and wind power. Today, electricity is the most common power source for turning mill stones.

Roller milling is the most common technique used by larger commercial mills today. In this extensive milling process, steel rollers crush the grain, and the flour released from the endosperm is separated by sifters into different grades of streams, according to fineness.The bran and germ, which make up about 28% of the kernel, are totally removed in this process. Roller milled whole wheat flour is produced by recombining ground bran with endosperm flour, but the germ is usually left out, because it would go rancid. The resulting flour may represent only 95% of the total grain by weight (Campbell et al., 1991). This paper can be reviewed at http://www.eap.mcgill.ca/Publications/EAP35.htm

Hammer Mills or Impact Mills are other types of mills that may be used by smaller operations. The grain is reduced in size to fine flour texture with the impact of steel blades turning at high speed.