This book documents case studies of community based food enterprises. It comes from Michael Shuman's non-profit. In addition to lots of examples this points out potential downfalls. There is a "Social and Environmental Performance" form designed to evaluate B Corporations that is interesting and of potential use for assessing local businesses.
The Wallace Center supports entrepreneurs and communities as they build a new, 21st century food system that is healthier for people, the environment, and the economy.
Has resources on how to build a food hub.