Rabbis turn to barcode analysis to worm out the truth
When rabbis from the Orthodox Union started finding worms in cans of sardines and capelin eggs, they turned to scientists at the American Museum of Natural History to answer a culturally significant dietary question: could these foods still be considered kosher?
Researchers at the museum’s Sackler Institute for Comparative Genomics used DNA barcode analysis to identify the species and life cycles of the parasitic worms and determine whether the food’s preparation violated Jewish dietary laws. The results, which were recently published online in the Journal of Parasitology, show that although the food contains a handful of species of roundworms, it is kosher.
“About 75 percent of all pre-packaged food has a kosher certification,” said Mark Siddall, a curator in the Museum’s Division of Invertebrate Zoology. “Many people, not just those in the Jewish community, look for this certification as a symbol of quality assurance in food preparation. If you’re a food provider and you lose that certification, you’re going to take a large hit.”
The study began last March, when rabbinical experts from the Orthodox Union, the largest organization that certifies food products for the Jewish community, brought a variety of kosher-certified sardines and capelin eggs to the Museum. Their concern: the presence of the worms might be a sign that intestinal contents were allowed to mix with sardine meat or preserved capelin eggs during food preparation. If that were the case, kosher certification would be compromised.
The key to determining whether the canned food was improperly handled is in the worms’ life cycles, Siddall said. “Some species of worms live in the muscles of fish when they’re in the larval stage,” he said. “Other species live in the fish’s intestines when they’re adults. We already know the life cycles for these parasites, so all we have to do is figure out what species were present in the canned food.”
To do this, researchers turned to DNA barcoding, a technology museum scientists have used previously to identify the presence of endangered whales in Asian markets, document fraud in the labeling of tuna, and determine the species of animals on sale in African bushmeat markets.
In this case, the scientists identified a handful of different nematode species, none of which are known to live in the guts of fish during their lifecycles. Therefore, there’s no evidence of intestinal worms co-mingling with the fish meat or eggs. As a result, the Orthodox Union issued a decision that the food remains kosher.
“This paper really exemplifies what science is all about - helping people,” said Sebastian Kvist, one of the paper’s authors and a student in the Museum’s Richard Gilder Graduate School. Other authors include Anna Phillips, from the University of Connecticut, and Alejandro Oceguera-Figuero, from the National Autonomous University of Mexico.