Bottled lemon juice contains concentrated lemon juice that is reconstituted with water and may contain lemon oil. Most bottled lemon juice, unless clearly labeled "preservative-free" or "organic," has added preservatives such as sodium benzoate, sodium sulfite, sodium bisulfite or sodium metabisulfite.
Any bottled lemon juice that contains sulfites must feature the ingredient on its label. Sulfites are sulfur-based compounds that manufacturers commonly add to bottled juices and a wide variety of other processed foods. Sulfites occur naturally in the beer- and wine-making processes. The U.S. Food and Drug Administration estimates that one out of 100 persons may be allergic to or have some sensitivity to sulfites, the reactions to which can range from mild to life-threatening. Since sulfite-free bottled lemon juice doesn't contain preservatives, it has a shelf life of only about eight weeks in the refrigerator.
Freshly squeezed lemon juice is generally preferable for cooking and baking since it has a brighter lemon flavor. However, bottled lemon juice is ideal for home canning since its level of acidity is regulated, whereas the acidity of fresh lemons varies depending on growing conditions and storage.
A teaspoon serving of bottled lemon juice has no calories and 1.2 milligrams of vitamin C.