Before Alton Brown flashed test tubes and Bunsen burners on the Food Network, before Wylie Dufresne made molecular gastronomy trendy in Manhattan, there was Harold McGee, author of the acclaimed On Food and Cooking. The food-science bible, first published 27 years ago, has sold more than 150,000 copies and can be found in most restaurant kitchens and on the shelves of any curious home cook. In it, McGee explains—among other things—how special bacteria turn milk into yogurt, why braising meat for a long time in low oven temperatures will make it fall off the bone, and how to keep fruit fresh longer. In doing so, McGee gave a whole generation of chefs and wannabes a crash course on why food looks, cooks, tastes, and spoils the way it does, with equal parts science and folklore to keep it all entertaining.

Last year, McGee published his third book, Keys to Good Cooking, and in May, the James Beard Foundation honored his original 1984 title by placing On Food and Cooking in its cookbook hall of fame. “I originally thought I’d write this book on cooking and then write about geology, the weather, or some other aspect of everyday science, but food turned out to be way too interesting,” he says on a foggy afternoon in his two-story Edwardian in Noe Valley. “You can’t do anything about the weather. You can suffer it, but that’s it. Whereas with food, you can get in there, make something, and enjoy it.”

In his regular column in The New York Times, McGee continues to explore cooking conundrums, such as finding the best frying oil (it doesn’t matter much; just buy small amounts, keep it dark and cool, and toss it when it tastes rancid), enhancing flavor in cocktails (add water), and deciding whether fancy salts are worth the price tag (they’re not unless you have a hyper-sensitive palate).

Still fascinated, McGee continues his detective work in his home test kitchen in the basement, where he’s working on his next book—this one on taste and the senses. His setup is minimalist: an electric stove (he has a gas one upstairs in the main kitchen to test different cooking methods), a small fridge, a 30-year-old microwave, a rack of chemicals, test tubes, books, and random convenience foods such as Minute Rice and boxed cake mixes (“Those cakes were very carefully formulated by chemists,” he says. “They get the job done if you’re trying to put a cake on the table.”)

As in his previous projects, McGee plans to learn as he goes along, simultaneously researching, writing, cooking, and testing his hypotheses. He sometimes begins in the backyard, where he’s transformed overgrown flowerbeds into a raised vegetable garden. He’s growing eight varieties of tomatoes, collard greens, beans, and herbs for future experiments and meals. “I’ve never made beet sugar, and I saw beet molasses in the store recently, so I’m growing sugar beets to see if I can make it,” he says. The small curry plant next to the thyme? “I can’t figure out why it has the aroma of that mix of spices we call curry. How did that happen?” For lunch, McGee pulls more than 15 different greens and herbs from the garden and tosses together a simple salad. From the pantry—filled with whole grains, a substantial liquor collection, and a long line of dried spices—he grabs olive oil to whisk with pressed garlic and pink sea salt. As a whole, the upstairs kitchen is surprisingly basic, an outdated remodel with black and white appliances, a few prized possessions such as earthy cassoulet pots from France, and a granite-topped island where he finishes dressing the salad.

From the fridge packed with butter, wines, cheeses, jams, sauces, yogurt and sourdough starters, and (gasp!) conventional brown eggs and milk, McGee pulls out an uncovered plate with funky-smelling duck gizzards confit. “They have a depth of flavor that duck meat doesn’t have, and duck meat is pretty flavorful to begin with,” he says, adding slices to the salad. When we sit down for lunch next to a loaf of Tartine bread, he waits for feedback. “One of the wonderful things about putting a piece of food in your mouth with someone else is seeing their reaction,” he says.

For dessert, he picks a ruby red cherry from a bowl, removes the pit, and cracks it open with a pair of heavy-duty pliers, releasing an almond-like aroma he says is key to what we taste in the fruit. “When you break into the seeds, you generate benzaldehyde along with cyanide,” says McGee. “I love finding out that part of what makes cherries so delicious is this aroma made by nature, packaged in a poison. But a little bit doesn’t hurt you.”

Now that his children are adults, he lives on his own, and his favorite weeknight meal is canned sardines, salad, a slice of bread, and a glass of wine—a step up from his very first cooking experiment. “It was a pound of bacon in a toaster oven when I was 10,” he says. “I did it in my room, and it didn’t take the kid sitter long to realize that something wasn’t quite right.” Today, he dines out a lot, often at Incanto in Noe Valley. On his refrigerator, he also keeps a list of chefs and restaurants he plans to visit (Benu, Commis, Corbett’s, Saison), preferring places that prepare things he wouldn’t have the chance to do on his own, like a delicate, custard-like tofu at Cyrus in Healdsburg. “Anybody these days can cook anything, using any ingredient and technique. I think food is going to become more like the art world, where you go to a restaurant not for a square meal but to see what’s on the mind of this really interesting person.” says McGee. “There aren’t really any rules anymore.”