Cinnamomum cassia has a sweeter flavor than Indonesian cassia, similar to Saigon cinnamon, but with lower oil content. Cassia bark (both powdered and in whole, or "stick" form) is used as a flavoring agent for confectionery, desserts, pastries, and meat; it is specified in many curry recipes, where Ceylon cinnamon is less suitable. Cassia is sometimes added to Ceylon cinnamon, but is a much thicker, coarser product. Cassia is sold as pieces of bark (as pictured below) or as neat quills or sticks. Cassia sticks can be distinguished from Ceylon cinnamon sticks in this manner: Ceylon cinnamon sticks have many thin layers
Spice a coffee grinder is useful for larger amounts. A frequently used spice such as black pepper may merit storage in its own hand grinder or mill. The flavor of a spice is derived in part from compounds (volatile oils) that oxidize or evaporate when exposed to air. Grinding a spice greatly increases its surface area and so increases the rates of oxidation and evaporation. Thus, flavor is maximized by storing a spice whole and grinding when needed. The shelf life of a whole dry spice is roughly two years; of a ground spice roughly six months. The "flavor life" of