Here’s some food for thought: One-third of the world’s food goes to waste every year. In the U.S., about 40 percent of our food gets thrown out. It’s happening on the farm, at the grocery store and in our own homes. Lately, there’s been a lot of talk about what to do about it — from auctioning off food that’s past its prime to getting restaurants to track their waste. Doug Rauch, the former president of Trader Joe’s, is determined to repurpose the perfectly edible produce slightly past its sell-by date that ends up in the trash. (That happens in part because people misinterpret the labels, according to a report out this week from Harvard and the National Resources Defense Council.) To tackle the problem, Rauch is opening a new market early next year in Dorchester, Mass., that will prepare and repackage the food at deeply discounted prices.