Wednesday, July 9, 2008

Spice and Spoilage

I recently came across an article from the March issue of Cornell University's Cornell Chronicle titled Study: Antibacterial spices explain why some like it hot. It describes the recent research done by Professor Paul Sherman, and the paper he published in the March 1998 issue of the journal Quarterly Review of Biology.

According to Sherman, some commonly used spices have significant antibacterial properties and may help prevent illness caused by food-born pathogens. More specifically, in the interview he said, "We believe the ultimate reason for using spices is to kill food-borne bacteria and fungi." Obviously this subject is of interest to a medieval food historian - medieval food preservation and disease prevention are a couple of those perennial hot topics. While I won't deny Sherman's claims outright, I do approach the whole thing with a good amount of skepticism.


My first question is on the degree of antibacterial properties of the 43 spices he's studied. At what concentrations were his tests performed? The article lists garlic and onion as being among the most potent germ killers, and states that "... they kill everything". I'm very sure I've had food go bad that contained both onions and garlic, and I know that mixing them in with raw beef won't make it safe to eat. This means that the concentration of the active ingredient is important, and this leads me to wonder if the amount of a given spice (say, cinnamon) needed to be an effective antibacterial agent would make the food inedible.

Sherman also draws a connection between latitude and spice consumption, with the inference that in warmer climates foods will spoil more quickly and therefore they need more spicing to prevent this spoilage. The article doesn't mention that the majority of spices (e.g. cinnamon, cloves, pepper, etc.) do not grow well outside of a tropical climate, meaning they'd need to be imported to the colder climates and would therefore be less likely to be used there. Did his study make any attempt to correct for this? If not, then it would seriously skew his data.

The article goes on to state that people "... probably aren't eating spices for their nutritive value, the biologist said, because the same macronutrients are available in similar amounts in common vegetables, which are eaten in much greater quantities." I know of one specific case that contradicts this: capsicum consumption in Mexico. The traditional Mexican diet would be severely deficient in vitamin C if it weren't for the consumption of capsicum peppers.

On the plus side, at one point in the article Sherman notes that the idea of using spice to cover the taste of spoiled food is bogus. He says that such a practice "... ignores the health dangers of ingesting spoiled food."

I'll have to see if I can get a copy of the original paper.

UPDATE: I've found one link that gives more detail on the paper, and it appears that some of my questions were addressed. I've also found a couple interesting links that discuss the antibacterial properties of some spices (see the links below).

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