ChewsWise Blog

ChewsWise Blog

Taste, Stress and the Rats' Choice


I'm often asked if "organic is better." Big question. But here's part of the answer from Harold McGee in the Times.

In a novel study, he writes, Swiss researchers offered rats identical biscuits made from organic and conventional wheat.

The rats ate significantly more of the former. The authors call this result remarkable, because they found the two wheats to be very similar in chemical composition and baking performance. In fact, the rats were better at telling the difference between organic and conventional foods than many humans have been.

Photo: basil flats

He pegs the choice to phytochemicals, healthful and potentially flavorful substances that are found at significantly higher levels in organically produced crops.

What do phytochemicals have to do with flavor? Phytochemicals are chemicals created by plants, and especially those that have effects on other creatures. Plants make many of them to defend themselves against microbes and insects: to make themselves unpalatable, counterattack the invaders and limit the damage they cause. Most of the aromas of vegetables, herbs and spices come from defensive chemicals. They may smell pleasant to us, but the plants make them to repel their mortal enemies.

Why should organic produce have higher phytochemical levels? The current theory is that because plants in organic production are unprotected by pesticides and fungicides, they are more stressed by insects and disease microbes than conventional crops, and have to work harder to protect themselves. So it makes sense that organic produce would have more intense flavors. For some reason, taste tests haven’t consistently found this to be the case.

But now the story really gets remarkable. Researchers at Clemson University exposed basil plants to a chemical, chitin, which is found in the exoskeletons of insects and crustaceans. The aim was to amp up the defensive reaction in plants by exposing them to this substance commonly found in pests. "The chitin from crab and shrimp waste is processed industrially to make a shortened form called chitosan, and this is what the Clemson food scientists used," McGee writes.

They soaked basil seeds for 30 minutes in a chitosan solution, then soaked the roots again when they transferred the seedlings to larger pots. After 45 days, they compared the chemical composition of leaves from treated and untreated plants. They found that at the optimum chitosan concentration, the antioxidant activity in treated plants was greater by more than three times. The overall production of aroma compounds was up by nearly 50 percent, and the levels of clove-like and flowery components doubled.

McGee says he is applying chitosan - commonly available as a dietary supplement - to his basil and cilantro plants, hoping for a similar effect.