Low-income communities can’t derive a lot of benefits from nutrition education if there aren’t any grocery stores in the area selling healthy food. But starting and running a supermarket is a capital intensive, low-margin business. The solution: mobile food markets that travel to low-income areas with food deserts. Such is the idea behind Fresh Truck, a Boston-based social enterprise that operates a 312-square-foot mobile indoor and outdoor food market. Inside, the food is in the…