KANSAS CITY — The nation’s two largest donut chains each announced on May 28 plans to offer a free donut to customers on June 5, National Donut Day. Dunkin’ Donuts, based in Canton, Mass., will give customers a free donut of their choice, with the purchase of a beverage, limit one per customer. Also on June 5, Dunkin’ will announce the winner of its "Create Dunkin’s Next Donut" contest. Krispy Kreme Doughnuts, Inc., Winston-Salem, N.C., is offering one free donut per customer with no purchase necessary to qualify. "Krispy Kreme is making life just a little sweeter for everyone on National Donut Day," said Ron Ruponcinski, executive chef. According to Dunkin’, National Donut Day was established more than 70 years ago by the Chicago Salvation Army.