Vitamin C in Tomatoes

A glossy Southern California coast magazine, the name of which will remain nameless, presented a dubious fact about tomatoes:

"...greenhouse varieties [of tomatoes] have only half the vitamin C of tomatoes ripened outdoors."

Detecting an environmentally correct (EC) slant to a commonly known commodity, I set about validating the statement. Why? Because the statement threw an unfair, if not incorrect, shot at greenhouse-grown tomatoes. This isn't uncommon, given the proclivity to 'clean' and 'natural' in this state.

In addition, the statement went on to gas the ethylene-gas-ripened tomatoes you get at the supermarket. The magazine statement proclaimed them close to inedible, nevermind gassed, OMG! I digress on gas-ripened tomatoes; that's another story.

Research online

The research literature on tomatoes is huge. So is the literature on nutritional values of foods. But picking out keywords 'tomatoes' and 'vitamin C' yielded search results even my research-averse, data-dumping proclivities could handle. Besides, Google's first-cited references must be the most relevant. Right?

Gahler et al (source cited below) published their tomato research in 2003. They said, and I quote:

"The phenolic content of tomatoes is significantly affected by the spectral quality of ambient solar UV radiation available."

This led me to believe the glossy magazine statement was right. But wait!

Translation

'Phenolic content' means certain chemical constituents of tomatoes. I won't go into the chemistry of phenols right here, but suffice it to say this compound group contains great antioxidants. Those are those compounds found in foods that slow the aging process, keep you young, healthy, fit, and reduce free-radicals, those bad age-related molecular mistakes. The trouble is vitamin C isn't a phenol.

'Spectral quality of ambient solar UV radiation' means the kind of light rays hitting the tomatoes that day. UV-A and UV-B are but two different ultraviolet wavelengths coming along with sunlight--and the unreported heat of the day and CO₂ concentration of the air. Neither temperature nor carbon dioxide content were controlled.

And, of course, 'significantly affected' led me on to believe affected in a good way, although I jumped to that conclusion all by myself.

Interpretation

My naturally skeptical nature, however, grew doubts at this point. Research in China produced a publication entitled, "Combined effects of enhanced ultraviolet-B radiation and doubled CO₂ concentration on growth, fruit quality and yield on tomato in winter plastic greenhouse."

It reported what I suspected, that being that the tomato story is not that simple. It is, indeed, much more complex. Thank goodness somebody translated it from Chinese. A shorter title is still in order.

The Chinese research directly linked enhanced vitamin C concentration in tomatoes not only grown in greenhouses but also in atmospheres with doubled CO_2--that environmentally incorrect gas we breathe out and plants love to breathe in.

Conclusion

This tells me my suspicions are right. The glossy Southern California coast magazine cherry-picked the data to make its environmentally correct point on tomatoes. This tells me to consider the source, then come to my own conclusions on everything from global warming to tomatoes.

Or is it, ahem, toe-MAH-toes?

Sources:
Gahler et al, J. Agric. Food Chem. 51 (2003), pp. 7962-68.
http://www.springerlink.com/content/358l224783571057/
A Southern California coast magazine that remains nameless because I don't want to be sued.