Eighty years ago my mother was in grade school where schoolroom paste was made by mixing a little flour and water together. Memories of that simple glue came back to her when she and I recently stood in my kitchen, mixing two small batches of flour and water. First I mixed regular “better for bread” flour with water in a little dish, then I did the same with special test flour made from soft durum wheat. The first mixture was a pasty, lightest-of-light-tan color; the second had a pale but clearly evident yellow hue.
The simple experiment was inspired by the hardness of different types of wheat. Soft white wheat is the easiest of all types of wheat to mill, weighing in with a hardness rating of only 25-35 on the scale millers use to measure such things. Soft wheat generally goes into products like noodles, cakes and cookies. Hard red wheat has a hardness factor of about 60-75. It is used for bread.
In contrast to its softer cousins, durum wheat tops out with hardness values ranging from 80-100. It is an unusual type of wheat, one with kernels so hard we don’t generally make it into flour at all. Instead, regular durum is ground only to about the consistency of sand-sized grains known as semolina. The semolina is then used to make pasta. In North America, durum wheat is grown in the dry parts of Montana, North Dakota and Saskatchewan, as well as in some parts of the desert Southwest.
Durum wheat has some advantages over other types of wheat from a grower’s point of view and also in terms of global food security. In some ways, durum is pretty primitive stuff: in the lingo of plant genetics, it’s “tetraploid” rather than “hexaploid” like most wheat. But durum has some highly desirable characteristics. It has better drought resistance and, in some instances, better disease resistance than the more common types of wheat.
It’s the hardness of the kernels of durum that has limited its culinary uses over the millenia, with durum used only for pasta and couscous while softer wheat has been made into flour and transformed into bread, gravies, and all the rest of it.
Enter onto the scene wheat researcher Dr. Craig Morris of the Agricultural Research Service housed on the campus of Washington State University. For 10 years Morris has worked to use classical wheat breeding techniques to introduce the genes for a soft kernel into durum wheat. Patient work in greenhouses and ultimately a few acres of farm trials has been going on year after year.
Now Morris can announce that he’s succeeded in his quest. He’s put the genetic information for soft kernels into the durum wheat plant. Hence my little experiment at home in the kitchen using test durum flour Morris had given me.
“In some places durum can out-yield hexaploid wheat,” Morris said to me in his lab. “We’ve thrown off the shackles of the hard kernel of durum. The sky is now the limit.”
To put it another way, world durum production has never been limited by the plant and how well it can grow. Instead, durum has been limited by what we can do with it in terms of food products. Until now, the fact that we didn’t grind durum into flour because it has been so hard kept durum as a poor cousin to hexaploid wheat strains.
The new soft durum can still be used to make pasta. It requires less energy to mill into semolina than hard durum, so that’s a positive. And perhaps better still, the new soft durum can also make flour and go into all the culinary products we are used to making from hexaploid wheat.
Morris and his co-workers are now waiting for the patent on the new type of durum wheat to be secured.
“Once we have that, soft durum is ready for prime time,” Morris said.
Agricultural research is something we’ve always done well in this country. Working behind the scenes at land-grant universities and in the Agricultural Research Service, many scientists contribute daily to technical progress we sometimes take for granted.
Here’s a toast for soft durum wheat and the choices it will give to growers, millers and consumers alike.
Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.