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Food Science


Chemists who cook share discoveries and memories

by Sam Lemonick
January 10, 2021 | A version of this story appeared in Volume 99, Issue 2


This chemist really blue it

Lots of people make something special for a holiday meal. Maybe it’s Grandpa’s twice-baked potatoes or a pecan pie you saw on Instagram. For Dani Schultz, the twist this Thanksgiving was blue garlic. She didn’t plan it, but she did solve the mystery of how it happened.

Photograph of a brine with blue-tinted garlic. A drawn structure of the pigment molecule responsible for the color is overlain.
Credit: Dani Schultz/C&EN
Azure alliums: Linked pyrrole molecules (structure shown) can turn pickled garlic blue.

Schultz, a Merck & Co. process chemist, had prepared a brine for her turkey: water, salt, herbs, lemons, oranges, and crushed garlic brought to a boil. When she lifted the lid and stirred the mixture, she realized her garlic had turned blue. Neither she nor her husband had seen or heard of anything like it before.

So, as one does, she went to the scientific literature. There she found an explanation from Shinsuke Imai and colleagues at House Foods (J. Agric. Food Chem. 2006, DOI: 10.1021/jf0519818). Schultz tells Newscripts that the chemical that gives garlic its smell, allicin, reacts in the presence of an acid (in this case, from the citrus fruits) with amino acids to form five-membered pyrrole rings. When several pyrroles bind together, the result is blue pigments.

She also learned that the reaction—or, at least, its azure effect—is well known to many. After she tweeted a picture of her garlic (shown here) and a figure from Imai’s paper, chemist Tianfei Liu of the State Key Laboratory of Elemento-organic Chemistry and Nankai University mentioned blue-green Laba garlic, pickled in vinegar and eaten on some Chinese holidays.

Schultz isn’t sure she’ll make blue garlic again, but she hopes others will, maybe as a way to show kids some cool food chemistry. Her tip: crush the garlic to break cell walls and release the enzymes that facilitate the reaction.


Bite-size memories

Cooking, chemistry, and Twitter intersected in a different way for chemist David K. Smith of the University of York. His new cookbook—a first for him—is Tw-eat, which Smith describes as a cookbook and a memoir.

Photo illustration of Twitter logo birds flying out of a pie.
Credit: C&EN/Shutterstock
Two and 80 characters: A new cookbook combines memories and recipes that David K. Smith and his late husband shared.

The project started as a collection of recipes for the family of his late husband, Sam, and for Smith and Sam’s son. Smith picked meals that had some memory of Sam, whether it was a simple weekday supper or a dish they shared on a special vacation.

Each page of the cookbook pairs a simplified recipe with an explanation of the food’s emotional resonance and a photo of the dish. Smith had already shared many of these ­recipes and photos on Twitter, so he borrowed the site’s conceit: almost all the recipes fit within 280 characters, more or less.

That limit required some concessions. The recipes tend to include only bare-bones instructions. Smith says they’re more like templates, which, along with the photo, will give people enough information to make the meals on their own. Others stretch into two or three tweet-length chunks. Smith tells Newscripts that his years of writing synthetic procedures in lab notebooks were good practice in brevity.

Some recipes are not exactly recipes. “Sam’s Mexican Fish Stew” was one of the last things he cooked for Smith. “I remember it tasted absolutely delicious.” Trying to re-create Sam’s recipe might not match the way Smith remembers it, so he simply includes the ingredients and a photo. Smith hopes readers will find their own ways to make the stew and other recipes and to make these dishes their own.

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This story was corrected on Jan. 12, 2021, to reflect that most recipes in David K. Smith's book Tw-eat do specify quantities of ingredients, but the book does not contain detailed instructions typical of most cookbooks.


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