As the Federal Reserve puzzles over what is holding back U.S. wages and productivity six years into the economic recovery, a pasta sauce company in New Jersey may offer some answers. Chelten House Products makes private-label sauces and dressings for high-end grocers such as Whole Foods, Trader Joe’s and Kroger, and has doubled its workforce to 300 over the past five years to keep up with a booming organic food market. Chelten CEO Steve Dabrow says factory work is becoming a harder sell with unemployment down at a seven-year low of 5.3 percent.