From humble potato farmer to supplier of the frozen French fry to McDonald’s, J. R. Simplot dedicated his lifetime’s work to potatoes and drove around with the number plate “Mr Spud”.

It was his innovative dehydration of the potato that led to his fortune, through two very different developments. His company initially supplied the American troops with dried potatoes and vegetables which kept them healthy during the Second World War. With the post-war widespread advent of the freezer, he developed the first commercially successful frozen chip and signed a deal to supply them to McDonald’s. Last year Forbes magazine listed Simplot as the 89th richest American, and the oldest living billionaire.

John Richard Simplot was born in Iowa in 1909. The family moved to Idaho where he grew up and attended school. Aged 14 he left his family and education and started work as a farmer, moving from animals to vegetables and becoming a potato farmer, sorter and processor. He set up his own company and, despite the financially difficult times of the Depression, ran more than 30 factories and became the largest supplier of potatoes in America. Roughly a third of the US military’s dehydrated potatoes and onions came from the Simplot Company.

Simplot was adaptable, which led him into diverse business ventures. When the war made fertiliser hard to get hold of, Simplot started manufacturing his own. When beef cattle farming looked profitable, Simplot accumulated a ranch in Oregon, rumoured to be the country’s largest. By the end of his life Simplot’s business interests also included oil, animal feed, ski resorts, and - in 1980, aged 71 - investments in PC microchips. His businesses made Simplot an influential figure, and he successfully protected his interests by lobbying President Reagan to impose tariffs on imported microchips.

It was, however, the edible chip for which Simplot will be best remembered. He was probably not the first person to freeze the chip, but, when a company scientist did, he exhibited characteristic business acumen and seized on the postwar trend for including freezer boxes in refrigerators. In the 1960s he signed a deal with Ray Kroc to supply McDonald’s, then in its early days, with potatoes, fresh Idaho russets and, once they tasted good enough, frozen. (Kroc had collaborated with the McDonald brothers to franchise the restaurants). He went on to supply the McDonald’s competitor Burger King and other American fast-food chains.

In 1973 Simplot retired from the company, but remained chairman, becoming chairman emeritus when his children took over in 1994.

In the 1970s he was charged with trying to manipulate Maine potato farmers and was barred from commodities trading for six years. He and his company were also fined $40,000 for failing to report income and claiming false deductions.

His first marriage ended in divorce, a son from the marriage predeceased him. He is survived by his second wife, Esther, two sons and a daughter.

J.R. Simplot, frozen chip pioneer, was born on January 4, 1909. He died on May 25, 2008, aged 99