Though he is now, among other things, an internationally known expert on the tortilla, Lloyd Rooney was a grown man with a Ph.D. before he first bit into one. This happened in 1965 or ’66, not long after he joined the Department of Soil and Crop Sciences at Texas A&M. He was raised on a wheat farm in Kansas—one of his earliest memories is of following his grandfather through a field of wheat—and for his doctorate in cereal chemistry at Kansas State he’d studied the browning of bread. Hired as a sorghum specialist, with funding to research sorghum quality for livestock feed, Rooney arrived at A&M with little experience of Mexican culture or Mexican food. Then came a fateful trip to South Texas for a “field day,” an opportunity for agricultural researchers and farmers to meet with one another. There, he ate something round and soft and wonderful.
“At that time I would have called it a ‘tor-till-a,’ ” he told me, pronouncing the word so that it rhymed with “gorilla.” Tortillas were then still a food that came from across the tracks. He became fascinated with them, though, especially corn tortillas, “because they were good, number one, and number two, when I asked questions about the making of them, the production, the chemistry, very little was known.” Tortillas were a promising candidate for study. “I came out of a program that was wheat bread, wheat bread, wheat bread. I was sick of wheat,” Rooney said.
I met Rooney at the 13th Annual Practical Short Course in Snack Foods Processing, held last April at A&M. I’d come there hoping to learn at least a little bit about tortilla chips, which, in addition to constituting, along with salsa, the official Texas state snack, have been a subject of scientific study in College Station for more than thirty years. If nothing else, I wanted to know who had undertaken that scholarly pursuit and why and what it consisted of; in my mind was a hazy image of a bag of chips, a dish of guacamole, and lasers.
Attendance at the course was down this year, which organizers attributed both to the global economic crisis and to the fact that they’d been unable to time it just before a snack food industry event known as SNAXPO. Nevertheless, on the first morning of the course, a couple dozen snackologists from around the globe convened early in the morning to listen to a lecture called “Extruders in Snack Food Preparation,” followed by a discourse on pressing issues faced by the industry, delivered by a man representing the Snack Food Association. Just for starters, the man complained, there was a tendency rampant in the media to label snacks “junk food,” whereas a preferable term would be “fun food.” Snacks have many adversaries, he implied. Among them seemed to be the state of California and the entire European Union.
Rooney, who deserves much of the credit for establishing Texas A&M as a center of tortilla studies, was up next. A wiry man of about seventy with a sergeant’s squint and a low, booming voice, he began with a sharp “Howdy!” It was as much a command as a greeting.
We howdyed back.
Wheat behaves differently than most other grains, in that when water is added to wheat flour, the flour’s proteins become hydrated and form a dough. Corn must be treated more aggressively to get it to gelatinize and form masa, the dough from which tortillas and tortilla chips are made. The crucial step is called nixtamalization. “That’s a fancy word to say we cook the corn in lime,” Rooney instructed the short course participants, emphasizing certain words by punching the final consonant, “and we remove the pericarp, the outer covering of the kernel.” To make masa, corn is cooked in the alkaline solution that results from adding ash or quicklime to water, then it’s steeped, washed, and ground. The Mayans figured this out; we’ll never know how—you don’t exactly just reach for the oregano and then decide to use ashes instead. As with so many aspects of cooking, the methods we take for granted much of the time seem strange and ingenious when you stop to consider them. Perhaps, Rooney speculated during his lecture, it was the invention of a wayward toddler. “If some enterprising person happened to put corn into the pot and their son or daughter threw ashes into there, they found out that that cooked the corn much more rapidly.”
As a young scientist, Rooney had wanted to probe how the whole tortilla-making process worked, from a chemical as well as a practical perspective. What was happening inside the corn kernel as it cooked? What caused the successive physical changes? What would happen if you tweaked the conditions?
But initially Rooney’s higher-ups didn’t find these questions as compelling, and it was years before he could secure the funding to establish Texas A&M as a center of tortilla research. He was supposed to be a sorghum guy. So in the mid-seventies, when he and his students nevertheless initiated a series of tortilla studies, they had to start quite literally from scratch, making masa with a hand grinder. Colleagues would tease them, asking, in Rooney’s recollection, “Why the heck would you want to work on tortillas?”
And not just tortillas. “We started with table tortillas, but the Frito-Lay company had pioneered in corn chips and then, with Doritos, the corn tortilla chips, and I happened to like both those snacks,” Rooney said. (Corn chips are fried masa pieces, whereas to make a tortilla chip you partially bake the dough first, then fry it.) So Rooney’s team chose to investigate tortilla chips in addition to tortillas. They studied corn hybrids, they studied alkaline cooking, they studied frying and rollability and breakability. Along the way, they had to ask themselves which qualities were most desirable: In other words, what makes a good tortilla chip good?
I have found no consensus regarding whether the tortilla chip ought to