Do Vinegar and Pomegranate Molasses Spoil, and How Can You Tell?

Acidic ingredients such as vinegar, pomegranate molasses, and citric acid last much longer than most foods because of their high acidity and generally do not “spoil” in the conventional sense. But that does not mean they never change: sediment may build up at the bottom of the bottle, the color may darken, or a thin layer may form on the surface over time.

What Changes Can You See in Vinegar?
In apple cider vinegar or grape vinegar, a cloudy, stringy substance collecting at the bottom of the bottle is a natural formation called the “mother of vinegar.” It is not a sign of spoilage; the vinegar is still safe to use, and this substance can even be used as a starter for making new vinegar. The color may darken a little over time, but that is not a real problem either. Actual spoilage in vinegar occurs only if the cap leaks or another liquid gets into the bottle; in that case, mold spots may appear on the surface, and the bottle should be discarded. This is extremely rare with pure vinegar.

What Is Different About Pomegranate Molasses and Citric Acid?
Pomegranate molasses darkens over time and becomes a little thicker; this is the natural concentration of the sugar and acid, and sometimes the flavor becomes sharper. But if a white, fuzzy layer of mold forms at the mouth of the bottle or there is a sharp smell of alcohol when it is opened, that is actual spoilage and the bottle should not be used. Citric acid, or “lemon salt,” is a dry powder and does not spoil in practice; its only risk is absorbing moisture and clumping. Clumped citric acid can be crushed and used again; it does not pose a safety problem.

How Should You Store Acidic Ingredients?
Vinegar and store-bought pomegranate molasses can be stored at room temperature in a cupboard away from direct sunlight; refrigeration is not required, but a cool environment slows changes in texture and color. Homemade pomegranate molasses, however, belongs in the refrigerator, and if a store-bought label says to refrigerate after opening, follow it. Tighten the bottle cap securely after each use to prevent insects from getting in and moisture in the air from entering the bottle. Citric acid lasts almost indefinitely in a sealed jar; the main risk is that the jar is not closed completely or is kept in a humid kitchen. Dipping a wet spoon into the jar is the most common cause of the rare spoilage cases seen with this group of ingredients.

What these acidic ingredients have in common is that their high acidity creates an environment unsuitable for most bacteria and molds. That is why bottom sediment, slight darkening, or increased thickness is not a cause for concern; the main warning signs are visible mold or a sharp smell that has turned alcoholic. Gently shaking the bottle before use can help distinguish mother of vinegar from a foreign substance at the bottom: the mother moves slowly without dispersing in water, while a foreign particle of dirt appears to have sharper edges. If you are unsure, replacing the bottle is the safest choice.

In short, spoilage is rare in this group of ingredients and is generally caused by a storage error, such as a leaking cap or a foreign liquid getting into the bottle.