If you shop at Walmart, you might be buying packaged produce unlike any ever sold in a U.S. store. The sliced apples or cut broccoli — the merchant won’t say what’s involved exactly — are being used to test blockchain, a new database technology. If successful, the trial could change how Walmart Stores Inc., which serves some 260 million customers a week, monitors food and takes action when something goes wrong. That could spur big leaps in food safety, cut costs and save lives…READ MORE