Aroma Nutrient Connection

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My grandmother used to say that “if it smells good it tastes good”, but science has increasingly discovered that if it smells good it may also be good for you.

A surprising fact about fruits and vegetables is that the substances that give them their appealing aromas (called “volatiles”) are manufactured on the same biochemical assembly line that produces the nutrients. In tomatoes for example, practically every one of the compounds that makes their fragrance and taste attractive is derived from a health-promoting nutrient.

Although tomatoes aren’t the only examples of this aroma-nutrient connection, they have been a focal point of much of the research on this subject. As in many natural foods, the attractive fragrance and flavor of a ripe tomato comes from a complex mixture of volatiles. However, the tomato also contains human nutrients including carbohydrates like fructose and glucose, small amounts of unsaturated fatty acids and essential amino acids, and micronutrients like vitamin A and lycopene. But what’s significant about this is that the tomato plant manufactures the fruit’s attractive volatiles from the nutrients that benefit us. For example, two of the tomato’s aroma volatiles, beta-ianone and a “heptanone”, are biosynthesized from vitamin A while most of the alcohols, ketones, and aldehydes that are also part of the mixture come from corresponding fatty acids, amino acids, or lycopene. Consequently, not only does the tomato produce human nutrients, it advertises their presence through the scent and flavor of its fruit. This yields a mutually beneficial quid-pro-quo in which we get nutrition and the plant gets to disperse its seeds. However, in some foods the link between nutrient content and aroma is broken, usually by human intervention.

For example, many of us have tasted or, more accurately, not tasted, varieties of cultivated tomatoes whose flavor has been bred away in attempts by farmers to increase shelf-life or crop yield. However, in many cases these fruits are no less nutritious than their more flavorful cousins. It is only that cultivation has inadvertently broken aroma-nutrient connection by disrupting the production of the volatiles from the nutrients.

On the other hand, the link can also be broken when the fragrance and flavor of a food advertise nutrients that really aren’t there. Good examples of this kind of disconnect are soft drinks and candies. These “foods”, have plenty of flavor, but that flavor has little to do with nutritional content.

The take-home lesson is that grandma was right, but only when it comes to natural foods. For others, a pleasant aroma (or lack of it) might just be false advertising.

By Dale E. Vitale, PhD Chemistry-Physics Dept. Kean University

References

Goff, S.A. and Klee, H.J., Plant Volatiles: Sensory Cues for Health and Nutritional Value?, Science 2006, 311, 815-819.

Klee, H.J., Improving the flavor of fresh fruits: genomics, biochem- istry, and biotechnology, New Phytologist 2010, 187, 44-56.

USDA, National Nutrient Data- base, http://www.nal.usda.gov/ fnic/foodcomp/search/, accessed 03/04/2011.