Daniel Charles

Chances are, you've never heard of ractopamine. But as of Monday, U.S. meat exports to Russia — worth $500 million dollars a year — have been suspended, all because of this obscure chemical.

Russian officials say American meat products won't be allowed into their country unless the meat is certified free of ractopamine.

There's a global campaign to force meat producers to rein in their use of antibiotics on pigs, chickens and cattle. European countries, especially Denmark and the Netherlands, have taken the lead. The U.S. is moving, haltingly, toward similar restrictions.

Many big food companies are caught in a dilemma these days. They want to rebrand themselves as merchants of health — Coca-Cola's new anti-obesity ads are just the latest example — but many of their profits still come from products that make nutritionists scowl.

If there's one person who symbolizes this tension, it's Derek Yach.

Now that the Christmas feast is over, you may be looking at all the extra food you made, or the food that you brought home from the store that never even got opened.

And you may be wondering: How long can I keep this? What if it's past its expiration date? Who even comes up with those dates on food, anyway, and what do they mean?

Here's the short answer: Those "sell by" dates are there to protect the reputation of the food. They have very little to do with food safety. If you're worried whether food is still OK to eat, just smell it.

Nobody really wants to think about economics, the famously dismal science, while sitting down at a table loaded with love and calories. Like it or not, though, supply and demand drive food production and set the price of dinner.

So, in a season of feasts, what are the business stories on your holiday menu?

Have you noticed, perhaps, that some of your store-bought salad dressings or spaghetti sauces taste a little less salty lately?

Probably not. The companies that make those products are doing their best to keep you from noticing. Yet many of them are, in fact, carrying out a giant salt-reduction experiment, either because they want to improve their customers' health or because they're worried that if they don't, the government might impose regulations that would compel more onerous salt reductions.