ABERDEEN - South Dakota has three classes of wheat, and ag experts say farmers and grain elevator workers should take care to make sure those different varieties are not mixed.

When different wheat types are mixed, the wheat's grade is lowered, according to Brent Turnipseed, South Dakota State University Seed Testing Laboratory manager in Brookings.

The margin of error is low, Turnipseed said. If there is too much of a combination, the wheat could be deemed "mixed."

Mixed wheat isn't good for much more than livestock feed, Turnipseed said, adding that it doesn't sell for as much as better-quality wheat.

The three classes planted in the state are hard red winter wheat, hard red spring wheat and hard white winter wheat, he said.

Each class has unique baking and milling qualities, Turnipseed said.

He said once processed into flour, hard red spring wheat is used for pasta, hard red winter wheat is used for breads and hard white winter wheat is used for cookies, pastries, cakes and Asian noodles.

Hard white winter wheat is becoming more popular in South Dakota, Turnipseed said. Farmers have planted almost exclusively red wheats.

Its popularity is growing because a study shows it tastes sweeter without as much sugar being added to baked goods, Turnipseed said, adding that sugar is a major cost for bakers.

Red wheat grown in South Dakota can be bleached by rain and look almost white, he said. White wheat, meanwhile, sometimes can have a red tint. A simple test can determine the difference, Turnipseed said.