Sarasota's Global Organic Specialty Source Inc., one of the biggest organic food distributers in the United States, was sold earlier this week to United Natural Foods, a nationwide organic, natural and specialty food distributor based in Rhode Island. Global Organic founder Mitch Blumenthal started the company with a single refrigerated truck and grew it into an operation with more than 100 employees and an 80,000-square-foot warehouse in south Sarasota. The website Supermarket News reported that United Natural Foods plans to merge Global Organic with its own Sarasota facility, located adjacent to the Global Organic warehouse. Terms of the deal were not disclosed.