Humidity

Humidity is not good for chocolate, because the sugar in the chocolate will absorb moisture. This is especially true for milk and white chocolates, which have a high sugar content. When the chocolate is stirred in a humid room, humidity can be incorporated into the chocolate and cause it to thicken. Sugar is hygroscopic, meaning that it will draw in the moisture from any outside source and hold it until it dissolves. As a result, sugar in chocolate can absorb moisture from the air (humidity), and the sugar will eventually dissolve out of the chocolate and cause sugar bloom. Sugar bloom is often caused by the surface moisture that can result from moving chocolate that might have been stored in a refrigerator quickly into a warmer room. Condensation will form on the chocolate, and the sugar in the chocolate will absorb the moisture, which dissolves the sugar and draws it to the surface. Eventually, the moisture will evaporate, leaving behind sugar that recrystallizes on the surface of the chocolate, resulting in a dull white film and chocolate that is dry and hard to the touch. Chocolate should always be stored in a place where the relative humidity is no more than 50 percent.