These small seeds are either black or white, roasted or raw. Black sesame seeds, both raw and roasted, are customarily used as a decoration or as an ingredient in the preparation of sweet pastry fillings or sweet soups. Roasted and raw white sesame seeds are generally used in dumpling fillings, as garnishes, or in the making of sweets. Sesame seeds are typically sold in plastic bags of 4 ounces to 1 pound and are occasionally sold loose. They can become rancid quickly if left at room temperature, so transfer them to a tightly capped container and store in the freezer for up to several months.