The choke cherry (Prunus virginiana) is a common shrub or small tree native to North America, recognized for its clusters of dark purple-black fruit. These berries have been historically utilized in various culinary applications, including making jams, jellies, and syrups, prized for their tart flavor. While the ripened fruit pulp is edible and safe for consumption, other parts of the plant contain naturally occurring toxic compounds. Safe use depends entirely on proper identification and preparation of the fruit.
Identifying the Toxic Components
The potential danger in the choke cherry plant is due to cyanogenic glycosides, specifically amygdalin and prunasin. These molecules are not inherently toxic but become dangerous when the plant material is crushed, chewed, or digested. An enzyme within the plant tissue triggers a reaction that releases hydrogen cyanide (HCN), a potent poison.
This chemical defense mechanism is concentrated in specific parts of the plant. The highest levels of the cyanogenic glycosides are found within the hard seed or pit inside the fruit, the leaves, and the bark. Wilted leaves can be particularly hazardous because the toxins become more concentrated as the moisture content decreases.
The ripe, fleshy pulp of the choke cherry berry is largely free of these toxic compounds, making it safe to eat. However, the pit must remain completely intact to prevent the chemical reaction from occurring in the digestive system. Consuming the fruit raw is not recommended unless the pits are deliberately avoided or spat out.
Recognizing Symptoms of Poisoning
Ingestion of sufficient quantities of toxic parts, such as chewed pits or wilted leaves, can lead to cyanide poisoning. Mild exposure may initially cause headache, dizziness, nausea, and vomiting. These effects occur as the body attempts to process the released hydrogen cyanide.
As the body absorbs more of the toxin, symptoms rapidly become more severe, reflecting the compound’s effect on cellular respiration. Cyanide blocks the body’s ability to use oxygen at the cellular level, effectively causing internal suffocation. Severe signs include difficulty breathing, a rapid heart rate, confusion, and abdominal pain.
In cases of significant exposure, the lack of oxygen utilization can lead to seizures, loss of consciousness, coma, and eventually, respiratory failure and death. Immediate medical attention is necessary if accidental ingestion of crushed pits or leaves occurs, especially in children or pets. Timely intervention can counteract the effects of the toxin.
Safe Harvesting and Preparation
Safely utilizing choke cherries requires meticulous separation of the edible pulp from the poisonous components. The first step in harvesting is to ensure that all stems and leaves are completely removed from the fruit before processing. This eliminates the most common sources of contamination before cooking begins.
During preparation, the primary rule is to avoid crushing or breaking the pits, as this releases the cyanogenic glycosides. Simple boiling or simmering the whole berries in water is the recommended method for extracting the flavor and juice. The heat from cooking helps to break down and neutralize any trace amounts of toxins in the fruit flesh.
After cooking the berries until they are soft, strain the mixture to separate the juice and pulp from the pits. Using a food mill, a sieve, or a jelly bag is necessary to mechanically remove the hard seeds without cracking them. The remaining pulp and liquid can then be safely used for making jams, jellies, syrups, or wine.