When it comes to the shelf life of bitters, it's important to distinguish between unopened and opened bottles. Unopened bitters, if stored properly, can last indefinitely without becoming unsafe to consume. However, the flavor and potency of the bitters can start to diminish after a certain period of time.
Once you open a bottle of bitters, it is exposed to air and other external factors that can affect its longevity. The general consensus among experts is that bitters can maintain their quality for about 5 years after opening. However, this is not a hard and fast rule, and there are several factors that can influence the lifespan of opened bitters.
One of the key factors is the ingredients used in the bitters. Bitters made with perishable ingredients like fresh fruits or herbs may have a shorter shelf life compared to those made with more stable ingredients. Bitters that contain glycerin, a common ingredient used to add viscosity and sweetness, can also have a shorter shelf life once opened.
Storage conditions also play a crucial role in maintaining the quality of opened bitters. It is advisable to store them in a cool, dark place away from direct sunlight and heat sources. Heat and light can accelerate the oxidation process, which can degrade the flavors of the bitters more quickly.
Another important aspect to consider is the bottle itself. Make sure the cap or cork is tightly sealed after each use to minimize the exposure to air. If the bitters come in a dropper bottle, ensure that the dropper is clean and free from any residue that may contaminate the liquid.
Personal experience has taught me that the flavor profile of bitters can change over time. After the five-year mark, the flavors can become mellow and muted. The vibrant and robust flavors that initially drew you to the bitters may start to fade. However, this doesn't necessarily mean that the bitters are no longer usable. They may still add some depth and complexity to your cocktails, just in a more subtle way.
To summarize, bitters can last indefinitely without becoming unsafe to consume when unopened. Once opened, their flavor and potency may start to diminish after about 5 years, although this can vary depending on the ingredients used and storage conditions. It is always best to use your judgment and sensory evaluation to determine if the bitters are still suitable for use.