A method of operating a combustor having a central nozzle and a plurality of outer nozzles surrounding the central nozzle is provided. The method includes providing a liquid fuel to only the plurality of outer nozzles at a specified total energy input. The method includes decreasing the liquid fuel to the plurality of outer nozzles while simultaneously increasing a gas fuel to the central nozzle and the plurality of outer nozzles to substantially maintain the specified total energy input. The method includes supplying a fuel-air ratio of the gas fuel to the central nozzle that exceeds a threshold value such that a central nozzle flame is anchored. An air-fuel ratio of the gas fuel to the plurality of outer nozzles is less than the threshold value such that a plurality of outer nozzle flames are lifted until a purge flow is supplied to the outer nozzles.