Sixteenth century brewers created amber beers by using a form of coal called coke to roast their grains. Coke burns hotter and more steadily than wood without imparting the foul odours that were given off from coal. It allowed brewers to produce caramel malts that were paler alternatives to the common brown porters of the period. At about the same time, Flemish migrants introduced hops to English beers and soon this ale became the chosen style of England from the mid-16th century until the end of the 20th century.