The results of the mouse study may not be known for a year or longer, but it builds upon research begun several years ago involving an earlier version of Alcalase-treated peanuts. In that clinical experiment, researchers applied microscopic amounts of extracts from treated and untreated peanuts on the inner forearms of nine human volunteers with peanut allergies and looked for any skin flare-ups. The results of this classic “skin prick” test were encouraging: Bathing the peanuts with Alcalase for three hours resulted in as much as a 60 percent reduction in the allergic response. Moreover, several participants had no allergic sensitivity whatsoever to the enzyme-treated peanut samples. Since then, Russell’s team has refined its Alcalase technique, further reducing the peanuts’ levels of Ara h 1, Ara h 2 and Ara h 6.

In the trial, though, the skin of a couple of the volunteers still reacted strongly to the treated peanuts. This underscores the challenge of engineering hypoallergenic foods: People may react to different peanut proteins, and some individuals are more sensitive than others. It’s hard to guarantee that Safer Peanuts would be safe for everyone to eat, even if they contained sharply reduced levels of certain allergens. For this reason, Russell says her product is not designed for peanut-allergic individuals to consume but rather for those who already eat ordinary peanut products. Her immediate goal is for a major food brand to make a special peanut butter with Safer Peanuts that, say, would be permitted at schools that ban regular peanut products to protect allergic students. But down the line Russell imagines major companies using Safer Peanuts more broadly in other products, both to eliminate deadly cross-contamination in the manufacturing process and accidental consumption in snacks and foods with hidden peanuts. “If you have a peanut-allergic child, this product would give you confidence to send your child out into the world where a peanut could creep into their lives,” Russell says, though this scenario faces substantial obstacles.

To even begin to try to realize this dream, industry experts say, the enzyme would have to work consistently within each batch. “You would have to be 100 percent sure that it penetrated every single peanut,” explains Patrick Archer, president of the American Peanut Council. He is similarly skeptical about applying genetics to make peanuts safer. “You would have to get every peanut seed variety in the country changed. Logistically and everything, it would be a challenge.”

Although the Alrgn Bio treatment process uses Alcalase, which has already been used in food products, the F.D.A. would most likely have to scrutinize peanuts that would be marketed as less allergenic. It remains uncertain how regulators might view claims like “hypoallergenic” or “reduced allergen.” Government regulations in the United States tightly control how claims about allergens can be made to consumers: If an alcoholic beverage, for instance, has gluten-based starting ingredients, it cannot be labeled “gluten free,” even if in the end it contains no detectable gluten. The makers of Omission beers, who remove gluten from barley during the brewing process using Brewers Clarex, another industrial enzyme, label their products in the United States as “crafted to remove gluten.” Still, these beers have a strong following, as does Lactaid milk, which relies on the enzyme lactase to break down the lactose sugar that causes digestive problems in some people when they consume dairy.

Genetic manipulation hasn’t worked to remove all of the allergens found in peanuts, and it faces an added hurdle, since many consumers are uncomfortable with the idea of genetically modified foods. The scientists bioengineering peanuts to lack allergens are hoping to eliminate genes from the final product, rather than introduce any new ones. This can be an important distinction in the eyes of some regulators. In April the U.S.D.A. determined that a white button mushroom genetically edited using Crispr technology to resist browning wasn’t subject to special oversight as a potential weed or pest by the agency, because the final product was free of foreign DNA. As yet, though, the F.D.A. has not approved label claims of reduced allergenicity in any foods sold in the United States.

There’s evidence that food producers may be open to adopting innovative peanuts. In the 1990s scientists announced they had developed peanut varieties that contained higher levels of oleic acid, which is thought to be healthy for the heart and which also gives the nuts a longer shelf life. These peanuts have gained strong industry acceptance: Last year, Mars Chocolate, the maker of peanut M&Ms and Snickers, announced that its North American products would contain only this kind by 2017. But James R. Baker Jr., an allergist who leads the nonprofit advocacy group Food Allergy Research & Education, is also unsure whether you can make a peanut that’s guaranteed to be safer and whether consumers will go for it. “There’s a theoretical potential there,” he says. “They’ll test in the marketplace whether this is rational. That will be the acid test.”

Burks, whose research into peanut allergies opened up the field, has focused his own work on therapies that retrain the immune system of afflicted individuals by exposing them to tiny amounts of this food. He is cautiously optimistic about altered peanuts, granting that they could perhaps one day be used for this sort of retraining. But Burks says that the goal of preventing accidental deaths by replacing peanuts for the general population with a safer version becomes ever more elusive as scientists discover more about how much the nature and strength of peanut allergy can vary from one individual to the next. “Everything we’ve learned about allergic proteins since the 1990s tells us the more we know, the harder it becomes to avert them.”