Buy Cook's Science today: http://amzn.to/212U0nCThe Science of Good Cooking: http://amzn.to/1O8oGw7Love melted cheese—on pizza, cheeseburgers, or in a grilled cheese sandwich? See the chemistry behind why some cheeses melt better than others.During our testing for Grown-Up Grilled Cheese Sandwiches (Cook's Illustrated, Sept/Oct 2013), we found that younger cheeses almost always performed better than aged ones. This is partly because aged cheeses have less moisture, making them prone to clump. But our science editor told us that there are other more complicated factors at play as well, so we ran another test and controlled for moisture.RECIPE for Grown-Up Grilled Cheese Sandwiches with Cheddar and Shallot: http://bit.ly/1caooGSEXPERIMENT: We purchased Cabot Creamery cheddars aged for three, 16, and 24 months (all were sealed against evaporation during aging) and baked slices from each block on top of inverted metal cups that we preheated in a 175-degree oven until each slice had melted.RESULTS: The three-month-old cheddar melted smoothly, evenly flowing down the cup's sides. Meanwhile, the 16-month-old cheddar showed signs of clumping as it slid down the metal, and the 24-month-old cheese actually broke into two large pieces and never melted.EXPLANATION: Moisture plays a part in how cheese melts, but the state of its protein—specifically, its network of casein protein—affects it most. In freshly made cheeses, casein proteins are in tightly wound clusters, allowing for little interaction with one another. As cheese ages, it goes through a process called proteolysis, in which bonds between individual casein molecules are "snipped," allowing the clusters to unwind and bind with other casein molecules, forming a matrix. Early in this process, the matrix is flexible, allowing young cheeses to melt smoothly. With time, the proteins bond together tighter, forming a stronger network that requires more heat to melt and is less flexible when melted. This can result in more separated fat and clumps, as with our older samples.America's Test Kitchen is a real 2,500 square foot test kitchen located just outside of Boston that is home to more than three dozen full-time cooks and product testers. Our mission is simple: to develop the absolute best recipes for all of your favorite foods. To do this, we test each recipe 30, 40, sometimes as many as 70 times, until we arrive at the combination of ingredients, technique, temperature, cooking time, and equipment that yields the best, most-foolproof recipe.Each week, the cast of America's Test Kitchen brings the recipes, testings, and tastings from Cook's Illustrated magazine to life on our public television series. With more than 2 million viewers per episode, we are the most-watched cooking show on public television.http://www.americastestkitchen.comMore than 1.3 million home cooks rely on Cook's Illustrated and Cook's Country magazines to provide trusted recipes that work, honest ratings of equipment and supermarket ingredients, and kitchen tips.http://www.cooksillustrated.comhttp://www.cookscountry.com
