Rats prefer organic biscuits over identical conventional counterparts; Basil is more flavorful and healthful when stressed like organic crops

by Craig Weatherby

The recent Disney cartoon movie hit "Ratatouille" is about a rat who, unlike his garbage-loving friends and family, has a palate so refined that he pines to become a gourmet chef.

It turns out that there's a grain of truth in this entertaining fable.

As we reported last July, Swiss researchers compared the effects, over 21 years, of three different agricultural techniques – organic, bio-dynamic (specialized organic), and conventional – on the soils and crops from three fields with similar soil compositions, subjected to identical crop rotation schedules.

While crop yields were lower in the organic and bio-dynamic systems, pesticide use was reduced by 97 percent and input of fertilizer and energy was reduced by 34 to 53 percent. (See “Organic Crops' Nutrition Advantage”.)

What we didn't know then was that the Swiss had also tried feeding otherwise-identical biscuits made from conventional or organic wheat to rats, to see if they would show a preference.

In what they described as an “integrative method” for assessing the eating quality of conventional or organic wheat, they gave lab rats a choice of biscuits made from organic or conventional wheat.

The scientists couldn't taste any consistent difference between the biscuits, and said they two kinds were very similar in chemical composition and baking performance.

But the rats clearly could detect a difference, and they ate significantly more of the organic-wheat biscuits.

In contrast, as kitchen-science writer Harold McGee noted in his New York Times article on the study, “In the handful of carefully designed taste-offs reported in the last few years, people were often unable to identify the organic foods, and often didn't prefer them.” (McGee H 2007)

Regardless of the reason, you have to hand it to the rats, who image as indiscriminate eaters seems undeserved.

Why would organic methods make food more appealing?

One explanation for the organic wheat's greater appeal to rats could be the higher levels of antioxidants and aromatic essential oils found in organic foods: a difference that results from the increased stress of having to fight pests and microbes without chemical assistance.

Exposure to pests and microbes elicits a defensive response in plants, which features increased production of specific antioxidants and essential oils that possess anti-microbial and anti-fungal properties.

As McGee reported, researchers at Clemson University wanted to see if stressing herbs in this way would enhance their antioxidant and aroma content.

Dr. Hyun-Jin Kim and Professor Feng Chen exposed basil seeds to chitosan: a compund derived from chitin, a polysaccharide found in crustacean shells. Applied externally to seeds and roots, chitosan induces responses in plants similar to the defensive moves they mount against microbes (Kim HJ et al 2005).

After 45 days, the plants stressed by the fake microbial attack showed definite advantages, on average:

  • Three times more antioxidant activity

  • 50 percent more aromatic compounds

  • 17 percent heavier and 12 percent  taller

  • 100 percent more “clove-like and flowery components”.

As they wrote, “Our study demonstrates that an elicitor such as chitosan can effectively induce phytochemicals in plants, which might be another alternative and effective means instead of genetic modification.” (Kim HJ et al 2005)

Professor Chen suggests that gardeners could enhance the aroma and flavor of home-grown herbs by repeating their routine:

  • Soak herb seeds for 30 minutes in a chitosan solution – precise concentration unknown, but probably not strong.

  • Plant the seeds to sprout.

  • Soak the roots once with the solution when you transfer the seedlings to larger pots, and water the herb with plain water after that.

You can get chitosan in capsule or powder form from many supplement retailers and web sites.


  • McGee H. Organic, and Tastier: The Rat's Nose Knows. Accessed online October 3, 2007 at http://www.nytimes.com/2007/10/03/dining/03curi.html

  • Kim HJ, Chen F, Wang X, Rajapakse NC. Effect of chitosan on the biological properties of sweet basil (Ocimum basilicum L.). J Agric Food Chem. 2005 May 4;53(9):3696-701.

  • Finamore A, Britti MS, Roselli M, Bellovino D, Gaetani S, Mengheri E. Novel approach for food safety evaluation. Results of a pilot experiment to evaluate organic and conventional foods. J Agric Food Chem. 2004 Dec 1;52(24):7425-31.