Color-changing cookies and appetizing ants

What makes these cookies green?

For a food chemistry class project, one of Lilian Were Senger’s students baked cookies. Instead of using peanut butter, she opted for sunflower-seed butter. Fresh out of the oven, the cookies looked nothing out of the ordinary—golden brown with a cracked top and soft appearance. But breaking a cookie in half revealed a green center. Within a few hours, the rest of the cookie started turning green.

“Initially I thought that it was a microbial reaction,” Were Senger, a food scientist at Chapman University, tells Newscripts. But she quickly realized, “It’s too soon for mold to be growing.”

Were Senger’s team hasuncovered the chemistry causing this color change. The main culprit is chlorogenic acid (CGA). Sunflower seeds contain high levels of CGA, which oxidizes to its quinone form during baking. The quinone then reacts with amino acids in the dough under high temperature and the high pH induced by baking soda to form green pigments.

The cookies are safe to eat, Were Senger says. “It’s just that people are not accustomed to seeing that color.”

But what makes the cookies green in the center first? It’s the moisture, she says. Over time, and in a more humid environment, the cookies attain greater green coverage on the surface. Of course, recipes that call for more baking soda result in more greening.

For the past few years, Were Senger’s team has been finding ways to minimize this greening. “Color affects our perception of foods,” she says.

One option is to opt for decolorizing agents such as sulfites. But their use can trigger asthma in people who are sensitive to sulfites. Another option is to add either the amino acid cysteine or glutathione, a peptide commonly used in cosmetics and touted for its role in skin lightening. Were Senger found that incorporating a food-grade version of cysteine or glutathione reduced greening. But she’s most excited by an enzyme from a class known as chlorogenic acid esterases that her team has shown to cleave CGA and eliminate greening in cookies made with sunflower-seed butter. The group is now studying whether the enzyme and its reaction by-products are safe for human health.

Edible ant flavors

Over the past decade, edible insects have gained attention as potentially promising protein sources. Insects have been part of many communities’ regular diet for generations. In parts of Africa, grasshoppers are a delicacy, and people boil, roast, or fry the critters before eating them as a snack or adding them to soup. In India, many Indigenous communities prepare a chutney using weaver ants.

Changqi Liu, a food scientist at San Diego State University, got a taste for edible insects when he visited food markets in Oaxaca, Mexico. His favorite were leaf-cutting ants called chicatana ants. “They have a very unique, nutty, smoky kind of flavor—and they’re a little bit woody also,” he tells Newscripts.

Liu has since been studying flavor profiles of chicatana and other ant species, using gas chromatography and mass spectrometry techniques to identify volatile compounds that contribute to the ants’ striking scents. Adult black garden ants, for example, have a vinegary odor profile, thanks to high concentrations of formic acid produced in their venom glands. Female and worker chicatana ants, on the other hand, are rich in 2,5-​dimethylpyrazine—a key component in trail-marking pheromones that lends the nutty, woody scent.

Liu’s team plans to test more ant species—profiling both larvae and adults, including individuals belonging to different castes within a colony. Honeypot antsare high on his wish list. Liu is also collaborating with New York City–based chef Joseph Yoon to drum up more interest in edible insects.

Please send comments and suggestions to newscripts@acs.org.