Properly prepared cherry wood is generally safe for burning in a fireplace or for use in cooking and smoking food. The persistent rumor that burning cherry wood is toxic stems from the fact that the cherry tree, a member of the Prunus genus, contains naturally occurring chemical compounds. These compounds are indeed poisonous if ingested raw, which is the source of the public’s concern regarding the smoke. When the wood is subjected to the high temperatures of a fire, these compounds are effectively destroyed. The primary hazards associated with burning any wood relate to general fire safety and the smoke produced by wood that has not been dried correctly.
The Source of Concern: Cyanogenic Compounds
The specific chemicals fueling the toxicity rumors are a group of compounds known as cyanogenic glycosides. These are found in many plants, especially those in the stone fruit family, including almonds, peaches, and cherries. In the cherry tree, these glycosides are concentrated in the leaves, the pits of the fruit, and, to a lesser extent, the bark. The wood itself, particularly the heartwood, contains very little of the compound.
When these plant parts are crushed or chewed, the glycosides come into contact with specific plant enzymes. This chemical reaction, known as cyanogenesis, releases hydrogen cyanide, a highly toxic substance. This is why wilted cherry leaves are hazardous to livestock. The toxicity is a natural defense mechanism for the plant, but it is entirely dependent on the chemical conversion process.
The Effect of High Heat on Specific Toxins
The process of combustion renders the cyanogenic glycosides harmless. Wood burns through a process called pyrolysis, where the heat breaks down the complex organic structure of the wood components, including any remaining glycosides. This thermal degradation begins at relatively low temperatures, starting around 220° Celsius, and is largely complete by 500° Celsius. Any cyanogenic glycosides present in the cherry wood are chemically destroyed within this temperature range, well before the wood bursts into flame.
Even if the initial thermal breakdown were to release trace amounts of hydrogen cyanide gas, the extreme heat of the fire’s flame zone acts as a secondary safeguard. The flame temperature of a typical wood fire easily exceeds 1000° Celsius, often reaching 1100° Celsius or higher. Hydrogen cyanide is an unstable molecule at such high temperatures. Within the flame, the gas rapidly decomposes into simpler, non-toxic components, primarily nitrogen gas and water vapor.
The combination of the initial destruction of the complex glycoside molecule and the secondary decomposition of any released hydrogen cyanide ensures that the smoke from a properly burning cherry wood fire does not contain hazardous levels of the toxin. The general toxicity of wood smoke, which contains particulate matter and other byproducts of combustion, poses a far greater concern.
Safety Considerations for Smoking and Cooking
Cherry wood is a valued, food-grade hardwood that is widely used for smoking and grilling due to the mild, sweet, and fruity flavor it imparts to food. The wood used for cooking, whether chips, chunks, or logs, must be from a clean, untreated source. It is important to confirm that the wood has not been exposed to chemical pesticides, herbicides, or wood preservatives, as these compounds would vaporize during heating and contaminate the food.
For smoking applications, many commercial wood suppliers remove the bark. The bark contains the highest concentration of the cyanogenic glycosides and can also harbor mold or debris. While the heat would neutralize the glycosides in the bark, using bark-free wood ensures the cleanest possible smoke flavor. The smoke itself is the medium for transferring the wood’s desirable flavor compounds to the meat.
General Wood Burning Safety and Preparation
The most important step for safely burning any wood, including cherry, is proper seasoning. Seasoning is the process of air-drying freshly cut wood to reduce its moisture content, ideally to below 20%. Cherry wood dries relatively quickly and is often ready to burn after six to twelve months of drying. Burning wood that is still wet is the single largest contributor to the real health hazards of wood burning.
Unseasoned, or “green,” wood produces a significant amount of thick, dark, and acrid smoke. This smoke is rich in fine particulate matter and unburned organic compounds, which are irritants and pose a health risk when inhaled. Wet wood also burns at a lower temperature, which leads to the formation of creosote, a tar-like substance that builds up inside chimneys. This creosote buildup significantly increases the risk of a dangerous chimney fire.
Properly seasoned cherry wood, like other hardwoods, burns cleanly, produces a pleasant aroma, and generates minimal smoke and creosote. Stacking the wood off the ground, covered from rain, and allowing air to circulate through the pile are the best practices for ensuring a safe and efficient fire. Focusing on using dry, clean, untreated wood is the most effective safety measure for any wood-burning application.