Is mushroom residue safe?

04/27/2014 12:00 AM

04/26/2014 3:00 PM

Q. It is often hard to wash off the growing medium from store-bought mushrooms. Is it safe to eat? Should the stems be further trimmed?

A. Although it is always a good idea to rinse off fruits and vegetables, the consumer is not at much risk from commercially grown mushroom residue, in the opinion of Kathie Hodge, an associate professor of mycology at Cornell.

“Even if you don’t clean the mushrooms, it’s probably fine,” said Hodge, who writes the Cornell Mushroom Blog.

Common grocery store mushrooms, Agaricus bisporus, which include the white button, cremini and portobello varieties, “are grown in what is basically compost,” she said. “It’s usually heat-treated, not entirely sterile, but a lot of organisms have been killed.”

Every producer has its own recipe, including organic things like straw, peat moss, manure if it is obtainable, canola meal or cottonseed meal, and inorganic things such as lime or gypsum. Then it is allowed to compost – that is, ferment – and then it is heat-treated, “trying to get rid of most things so the mushrooms will take over,” Hodge said.

How do probiotics survive stomach acid?

Q. When you eat yogurt or take a probiotic supplement, why aren’t the probiotic bacteria killed by stomach acids?

A. The point of consuming a probiotic supplement in a food such as yogurt, a powder or a capsule is to introduce beneficial bacteria in the gut, said Dr. Christine Frissora, a gastroenterologist at the Center for Advanced Digestive Care at NewYork-Presbyterian/Weill Cornell hospital.

There are questions about whether these bacteria survive the gastric acid, make it down to the small intestine or colon and live to have any biological effects.

“Certain bacteria have the capability to survive gastric acid, and others do not,” Frissora said.

Some bacteria have a polysaccharide (or complex carbohydrate) capsule that protects the inner organism like armor, she said. Others have a complex electrolyte pump that pumps acid out of the cell, providing protection from destruction.

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