Daniel Charles

A few months ago, I let you in on a little secret about Greek yogurt. Not all of this extra-thick, protein-rich yogurt is made the old-style way, by straining liquid out of it it. Some companies are creating that rich taste by adding thickeners, such as powdered protein and starch.

If you've ever checked the ingredient list on a PowerBar or a high-protein smoothie, you probably have stumbled across these words: "Whey protein concentrate." You'll find it in a growing number of prepared foods.

This mysterious ingredient is derived from one of the oldest of human foods — milk. But capturing it requires huge factories that look more like oil refineries than farms.

Here's an astonishing fact: Half of America's mushrooms are grown in one tiny corner of southeastern Pennsylvania, near the town of Kennett Square.

But why? It's not as though this place has some special advantage of climate or soil, the kind of thing that led to strawberry fields in Watsonville, Calif., or peach orchards in Georgia. Mushrooms can grow indoors. They could come from anywhere.

When Zarrina Mulloboeva got invited to go apple picking the other day, she thought it would be a taste of home. She's an exchange student from Tajikistan, in central Asia — a country close to the ancestral homeland of apples. Her uncle has a small orchard. In fact, when Mulloboeva came to the United States six weeks ago, she brought with her a large bottle of homemade dried apple slices.

Can there be too much life-saving peanut butter?

In Haiti, two different humanitarian groups have built new factories to make this product, which is used to treat severe malnutrition and maybe someday prevent it. The problem is, Haiti doesn't appear to need two of them. Each factory, all by itself, could satisfy Haiti's current demand.

How much extra would you pay for local food? It's a familiar question. We face it practically every time we shop for groceries, either at the store or at the farmers market. But what about food that can save the lives of severely malnourished children?