LEWISTON — Michael Dupuis wants to be a coffee evangelist.

The 44-year-old software developer became a home coffee roaster to avoid the bitterness he tasted in most coffees.

He learned about the raw beans, which look like pale, shelled peanuts until they are heated, turn a chocolate brown and expand.

Dupuis has also expanded.

He has given up his home roaster — a small contraption that resembled a toaster oven — and has turned pro.

Dupuis has created his own business, Great Falls Coffee Roasters.

Standing beside a whirring $5,000 hot-air roaster, Dupuis explained that the beans lose about 15 percent of their weight during the process. All of their moisture is sucked out, and the beans’ outer layer begins to crack.

Inside, the beans began to sound like popcorn.

“They call that ‘the first crack,'” he said.

The noise calmed and then started up again a few minutes later. After 18 minutes total, the roasting was finished.

After the beans cooled, Dupuis dumped them into a plastic bin. Then, they went into brown bags for sale. Even before he labeled them with his brand, he stamped the date.

“Freshly roasted coffee should be consumed within two weeks,” he said. “Ideally, you get it every week, and you buy just enough for your week.”

It’s the kind of advice he hopes to share as his business grows. Though his coffee is now available at The Vault on Lisbon Street and online at GreatFallsCoffee.com, he hopes to open his cafe in Lewiston-Auburn.

It’s a long distance from his other job as a software developer for Apple’s iPhone, iPad and Mac computers. Dupuis grew up in Lewiston and lived in Massachusetts and New Hampshire for 18 years. He was one of the founders of Advenio, which made a popular recipe application, MacGourmet.

Dupuis sold the company last year. And though he still works on some software projects, his focus is on his beans, which are stored and roasted in a downtown mill building.

But his little corner space — with his roaster, shelves and bags of beans — is incomplete. He can’t retail the coffee from his office. And though the aroma fills the room and flows out of the vent while he’s roasting, he has nothing there to brew coffee.

He settles with a single cup of coffee — poured into a 24-ounce latte cup — every morning.

That’s my one cup a day,” he said. “Sometimes I’ll have an afternoon cup. I typically don’t, though.”

Preparing that one cup is not a passive activity, however. He must choose just the right roast. And it must be ground just before being brewed.

Dupuis has hosted tastings at The Vault, part of the coffee art and science he wants to share with folks.

Savoring coffee can be like tasting wine. Though it’s less about the aroma than the flavor on the tongue, there are infinite subtleties to appreciate, including the flavors of certain coffee beans and their roasting methods.

“You get really into coffee,” he said. “There are a million ways you can roast it.”

At a tasting and on his first sip of any coffee, Dupuis always drinks the elixir black.

But at home, he surrenders to sugar and cream.

“I almost feel bad saying that,” he said.

dhartill@sunjournal.com