To avoid penalties written into its Army contracts for failing to make enough creamer, the company had overproduced, leaving its warehouse all but overflowing with valuable, perishable dried milk. “The product had a wonderful flavor,” Mr. Sanna once wrote. “I believed that it would make an excellent ingredient for a hot cup of cocoa. To confirm my belief, I consulted the family cookbook.”

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Testing his recipe with the help of his five children, then calling on the taste buds of kids at a parochial school in their town of Menomonie, Wis., Mr. Sanna created what became known as Swiss Miss — a powder that, poured into hot water or milk, became a favorite of Antarctic explorers and launched the instant-hot-chocolate industry in the early 1960s.

He was 101 when he died March 13 at a hospice center in Fitchburg, Wis., a suburb of Madison. The cause was heart and kidney ailments, said his son John Sanna.

Trained as a mechanical engineer, Mr. Sanna began his career maintaining blast furnaces and coke ovens for U.S. Steel. But he “had an amazing ability to taste things, and an amazing sense of smell,” his daughter Lucy Sanna said in a phone interview. “You could give him a cookie, and he’d say, ‘The nuts are rancid,’ even if it was only a small part.”

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After figuring out how to turn surplus military milk powder into a delicious, highly portable beverage, Mr. Sanna set about bringing the product to market. His brother Tony Sanna gave it the somewhat misleading name Brown Swiss, after a breed of dairy cow — Sanna actually used Holsteins, which produce a higher volume of milk with less butterfat — and the mix found some early success after it was sold to airlines.

“Business started going down because the product was quite expensive and people were taking it home,” Mr. Sanna told the Wisconsin State Journal in February. The airlines stopped purchasing it. “We saw that as an opportunity.”

Returning to the kitchen, where he reworked the recipe with the help of his children once again, Mr. Sanna replaced the whole milk of the creamer with powdered skim milk, which was cheaper and gave the cocoa mix a longer shelf life.

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The new product was named Swiss Miss, the title of a film by the comedy duo Laurel and Hardy. Marketed with mail-order Swiss Miss dolls, it spawned similar mixes by Carnation, Nestle and Hershey.

In 1963, an article in the Eau Claire Leader reported that the Sanna company’s “dry creamed cocoa” was a hit even in Antarctica, where it was “provided constantly as a menu item” at McMurdo Station, a U.S. research center. The commander of a Navy icebreaker said he was “most impressed” with the beverage, and when adventurer Will Steger departed in 1989 for a dog-sled trek across Antarctica, he said he made sure to pack enough Swiss Miss to make 2,070 cups of hot chocolate.

Mr. Sanna was long retired by then. His family sold Sanna Dairy to Beatrice Foods in 1967, and Mr. Sanna went on to play the stock market, hone his golf game (he designed and built a special face-balanced putter) and — at age 89, in 2006 — to publish a children’s story. “Daddy, Daddy, There’s a Mouse in the House!” chronicled his attempt to remove a mouse without killing it. He used a vacuum cleaner, much to the delight of his grandchildren.

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Since 1990, Swiss Miss has been part of Conagra, which says it sells more than 50 million boxes of the cocoa mix each year. Mr. Sanna said the mix’s taste had diminished somewhat through the years, beginning when he switched from whole milk to skim creamer.

Still, he said, “It’s nice to know that you’ve done something that will carry on.”

Charles Albert Sanna was born in Philadelphia on Nov. 9, 1917. Both parents were Italian. His Sicilian-born father came to New York at age 13 and later managed a dairy company in Philadelphia, an ice cream company in Washington and a gelatin operation in Chicago. During the Depression, he worked in the federal Agricultural Adjustment Administration.

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The family eventually settled in Madison, where Mr. Sanna graduated from high school and attended the University of Wisconsin. He received a bachelor’s degree in mechanical engineering in 1939 and joined the Navy two years later, rising to become a superintendent of submarine construction at Portsmouth Naval Shipyard in Maine.

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While there, he met Margaret “Peggy” McGee, his boss’s secretary, whom he married in 1946. In addition to his wife, survivors include four children, five grandchildren and two great-grandchildren. He was predeceased by a daughter.

After World War II, Mr. Sanna’s father persuaded him to join the family business, then known as Sanna Dairy Engineers. The firm’s management team came to include Mr. Sanna’s three brothers, as well as a brother-in-law. The business found early success with a nonfat dry milk dubbed Sanalac and also produced cream for Campbell’s Soup.

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Mr. Sanna proved crucial to the company’s efforts, perhaps most notably with the design of a 60-foot-tall stainless-steel dryer in Menomonie, described as the largest in the world. But his thoughts often turned from powdered milk and dried egg whites to the submarines he had helped build during World War II and to the men who worked and sometimes died inside of them.

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“These men had to be utterly perfect, particularly mentally,” he wrote near the end of his life. “I would ask that anything said on my behalf would include a statement of tribute to the 3,505 valiant, unheralded submariners of the United States Navy who lost their lives in World War II.”