Josh Klein used to work on vaccine development for HIV, but these days he focuses on a different biochemical conundrum: making cakes moist and fluffy. He insists he's still making a difference. As director of biochemistry research at Hampton Creek Foods in San Francisco, Klein is on a mission to systematically identify and replicate every single culinary function of chicken eggs—using plant proteins.

Although Hampton Creek's founder, Josh Tetrick, is a vegan, his goal is not to convert others. Instead Tetrick hopes that Hampton Creek's products will outcompete eggs on price and thereby “sneak sustainability” into a variety of diets. The company, which is backed by tech-centric venture capital firms, recently launched a mayonnaise alternative, Just Mayo, and an egg substitute, Beyond Eggs, for making cookies.

As targets for ecological overhaul go, the egg industry is a good one. The world's hens lay more than one trillion eggs a year, and they do so with startling inefficiency. Egg farming requires 39 kilocalories of energy to produce one kilocalorie of protein—on par with raising cattle for beef—according to a 2003 study in the American Journal of Clinical Nutrition. The energy-to-protein ratio for plants is 2.2 to one.

Whereas there are other egg substitutes on the market for allergy sufferers and conscientious objectors alike, Klein says he is taking a more scientific approach. His team has scanned more than 1,500 plants, identifying 11 as strong candidates for egg stand-ins. “The egg is more than just a nutrient,” he says. “It reacts to things like temperature, pH and salt content.” By identifying proteins that perform specific functions—emulsion, coagulation, aeration, and so on—Klein and Tetrick say that Hampton Creek's products, taken as a whole, will be the first to totally replace eggs without sacrificing taste.

Next up for Hampton Creek are a premixed cookie dough—which can be eaten raw without fear of salmonella—and a replacement for scrambled eggs. The powdered egg replacers already on the market generally cannot be scrambled, and many liquid products are actually egg-based.

Having tackled breakfast, Hampton Creek will attempt to fill the egg's role in airy baked goods. It will take “very hard work” to replace the egg yolk's structure-building lipoproteins, predicts Marc Anton of the French National Institute for Agricultural Research. In a typical batter, egg proteins surround air bubbles trapped in the mixture by sugar and fat, and the heat of baking seals the bubbles shut. The complexities of the process leave plenty of room for error. Even still, Klein and his team think they may already have found a plant candidate that can hold up a pound cake with egglike panache.