Florida State University : Research in Review

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NUTS!

To most of us, they're delicious—to others, they're deadly. Finally, food scientists are fighting back.


Even the most creative chef would be hard pressed to find a more versatile, celebrated nut than the almond.

Greeks have showered them sugar-coated over newlyweds. Swedes hide them in rice pudding at Christmas. North African Jews serve cakes crunchy with whole almonds during Passover. They can be sliced into slivers, squeezed for oil and ground for marzipan—or savored simply, deliciously raw.

The buttery kernel has been cultivated for thousands of years and permeated so many cultural rites that it is difficult to avoid. But for the millions of people around the world who are allergic to the ubiquitous nut, their almond ritual is one of total abstinence.

Though peanuts are far more notorious for inducing severe allergic reactions, even death, almonds and other tree nuts can be just as threatening. And while more people are allergic to shellfish, tree nuts such as almonds, walnuts and cashews as well as peanuts rank among the worst offenders. One study, published in January 2001 in the Journal of Allergy and Clinical Immunology, found that out of 32 food allergy deaths in the country, more than 90 percent of the cases were triggered by peanuts and tree nuts.

That's bleak news for the 3 million Americans who have to be on the alert for peanuts and tree nuts in restaurants and grocery stores. Most peanut and tree nut allergies aren't outgrown, and currently, there is no cure for either, which makes avoidance the best defense, said Shridhar Sathe, professor of food science and one of few internationally recognized tree nut experts.

The strategy sounds simple enough, but it's not always easy to pull off. A 2006 report on food allergies from the National Institutes of Health disclosed that one out of four people with a food allergy are accidentally exposed to an offending food. Often, this happens when someone eats a food product that has been declared free of certain allergens but that has been contaminated during processing.

For example, a so-called ”nut-free“ chocolate bar can become contaminated by almond residue that sticks stubbornly to processing equipment. Innocuous for most people, but for those who are extremely allergic, even small traces of an accidental nut protein can mean, literally, a heart-pounding, dizzying trip to the emergency room.

The good news is that many of these hospital visits can now be prevented thanks to the work of a handful of diligent scientists in a field that they say has persevered despite disinterest by the federal government and a drug industry that heavily influences the direction of health research.

Sathe is one of these scientists. To tame a potentially deadly food allergy into a manageable one, Sathe built his more than 30-year research career around identifying, purifying and testing the proteins to assure that nuts are made as benign as possible to everyone.

Perhaps the most dangerous threat to people who suffer from food allergies is one that often goes undetected and is difficult to control: contamination in food processing plants. In theory, said Steve Taylor, professor of food science and technology at the University of Nebraska-Lincoln, food manufacturers should be able to cleanse the equipment they use for processing different foods so there is no cross-contamination. But in testing food products in his lab, Sathe has found contamination does happen.

So how do manufacturers catch this kind of allergen pollution—especially for the foods that cause the most severe reactions? Finding a method has taken scientists years, with Sathe at the field's forefront.

”He's done a lot to help identify which proteins are the allergens,“ Taylor said. ”I consider (Sathe) one of the world experts on tree nut biology, biochemistry and allergies.“

Timing turned out to be one of Sathe's biggest allies in achieving this stature. He had zeroed in on the almond, the delicately flavored nut, rich in vitamin E and touted for its cholesterol-reducing potential, long before most of the food industry, regulators or even most scientists took food allergies seriously

So the field was wide open. No one even knew which proteins in tree nuts were triggering allergic reactions, and Sathe had a springboard for a prolific research program.

”First you identify which protein is responsible (for the allergic reaction),“ Sathe said.

To do this, Sathe and his lab team start with whole nuts. They keep their refrigerator packed with plastic storage bags full of tree nuts, from Hawaiian macadamias to Brazil nuts. With a mortar and pestle or blender, they grind the almond seeds into a soft powder, then remove the fat from the flour to extract and isolate the proteins. Next, they treat the almond proteins with a solution of human antibodies that are responsible for triggering an overblown immune response—a result of mistaken identity when a body accidentally labels a harmless protein as a threat and triggers an allergic reaction.

In Sathe's experiments, one protein, called almond major protein, emerged as the dominant player in almond allergies. And, as it turns out, more than 10 years earlier Sathe had been the first to identify the protein and demonstrate that it comprises 65 percent of the nut's total protein content.

Now Sathe and his collaborators had shown the protein triggers allergies in its raw form.

But what if the protein is baked, microwaved, fried or blanched, as the nut is often prepared?

Sathe and his collaborators, including Kenneth Roux, FSU professor of biological science, tried blasting almonds with various processing and cooking methods to see whether they could alter the proteins so the antibodies would no longer be able to recognize them.

”It's important to know whether upon processing, this (protein) still retains its reactivity or not,“ Sathe said. If cooking tree nuts could render the allergens harmless, it would bring some relief to people who have been assiduously avoiding them.

Sathe's lab repeated the same series of experiments with the allergy-inducing walnut and cashew proteins that Sathe and his collaborator, Suzanne Teuber, at the University of California-Davis were the first to identify. (Sequencing the protein codes has led to two patents on walnut and cashew proteins.)

Despite being microwaved, roasted, pressure-cooked, blanched or fried, the dangerous proteins proved quite stubborn.

But instead of a setback, Sathe and his team soon found their research line veering into a whole new direction.

Sathe shifted gears to develop a method that detects the protein in tiny amounts.

Since then, others have developed kits based on Sathe's research that can sniff out major almond (as well as hazelnut, walnut and cashew) allergens at remarkably low levels, between 10 to 100 parts per million.

But there's always room for improvement. The most sensitive allergy sufferers react to protein traces lower than what current tests can sniff out. Plus, existing methods test for only one allergen at a time.

Sathe is now developing tests to detect trace amounts of walnuts, cashews, Brazil nuts and pecans, and he's working toward a way to test for multiple nut allergens at once. The technology to create a multiple-food detector is by no means brand new; progress is just a matter of time and resources, Sathe said.

Sathe's science could also spur major clinical advancements in allergy medicine. The same method that applies in the food industry could help physicians diagnose food allergies faster, Sathe said.

And ultimately, even the most sensitive allergy sufferers might be able to ask the question 'What's for dinner?' with happy anticipation.