I know James Bond has a preference, but is there a big difference between a shaken martini and a stirred one?
Believe it or not, this is actually something that has been studied scientifically and has an interesting answer!
In 1999, researchers at the University of Western Ontario in Canada decided to investigate the antioxidant properties of martinis and how they are affected by the martinis' preparation.
As you may know, antioxidants can help protect against tissue damage that leads to heart disease and cataracts, and James Bond seems to be pretty tough with good eyesight, so this seemed a reasonable subject for study. (In fact, the authors of the study cite James Bond as their motivation in their paper in the British Medical Journal. They even conclude, "007's profound state of health may be due, at least in part, to compliant bartenders." -- Who says scientists don't have a sense of humor?)
They studied the martinis' ability to deactivate hydrogen peroxide -- the stuff that's used to bleach hair and teeth, or to disinfect cuts and scrapes.
While the detailed chemistry is not fully understood, shaken martinis are much more effective than either gin or vermouth alone at deactivating hydrogen peroxide, and about twice as effective when shaken as opposed to being stirred.
That said, Eben Klemm, a former researcher at the Whitehead Institute for Biomedical Sciences in Cambridge (and now a bartender in Manhattan), has been quoted in Chemical and Engineering News as saying that the taste of a stirred martini is superior.
As is so often the case, it's hard to get something without making some sacrifices.
For people interested in further research, it seems that the contribution of olives, which also have antioxidant properties, has yet to be investigated.
Dr. Knowledge is written by physicists Stephen Reucroft and John Swain, both of Northeastern University. E-mail questions to email@example.com or write Dr. Knowledge, c/o The Boston Globe, PO Box 55819, Boston, MA 02205-5819.