A dispensing valve assembly for dispensing a fluid product and preventing air from being drawn into the fluid product through the valve includes a flexible diaphragm valve (10, 50, 100) and a valve seat insert (12, 58, 102). The flexible diaphragm valve flexes from a concave closed position to a convex open position in which fluid product is dispensed through a dispensing opening (26, 56, 116) in the diaphragm. The valve seat insert is positioned adjacent an inside surface of the diaphragm valve in its closed position to prevent the valve from buckling inward and prevent air from passing into the fluid product through the valve.