Does Lemon Juice Go Bad?

It is often said that the high acidity in lemon juice prevents its from spoilage, no matter how it is stored. However, this notion is absolutely untrue. Lemon juice too can go bad if not refrigerated.
Tastessence Staff
Identifying Spoiled Juice
Check the taste, smell, and color or appearance of lemon juice to determine whether the juice has gone bad. Spoiled juice appears dark yellow, its odor or smell is extremely sour, and moreover, it loses its natural taste.

Citric acid is a natural preservative, hence many believe that lemon juice that is high in citric acid is unlikely to go bad whether it is left at room temperature or refrigerated. However, this is not the case as lemon juice can also spoil when not stored properly.
Although initially, citric acid will slow down bacterial growth that spoils the juice, it does not take too long for the bacteria to multiply and contaminate the juice. Other pathogens such as mold and yeast may also proliferate and cause spoilage. So lemon juice does go bad, but you can always increase its shelf life by practicing appropriate storage methods.
How fast does it go bad?
It all depends on how it is stored, and the type of lemon juice. It is discussed below:
Fresh Lemon Juice
Leaving fresh lemon juice prepared by squeezing the lemon, at room temperature, is like an open invitation (40ºF to 140ºF) to spoilage. It will not last for more than a day if it is not stored in a refrigerator. However, usually, it spoils within hours after storing it at room temperature. Whereas, when refrigerated, you can increase the shelf life of the fresh juice to 2 to 3 days. Make sure to adjust the thermostat to a colder setting so that the temperature of the refrigerator is between 32ºF to 40ºF. The USFDA also advises to refrigerate the juice immediately in an airtight bottle.
Freezing the lemon juice is the best way to increase its shelf life substantially. Fresh frozen juice when stored in the freezer has a shelf life of up to 6 months. It is the most reliable way of preserving juices and food. This is because at freezing temperatures, bacteria and other pathogens that cause spoilage are unable to regrow or multiply.
In order to freeze the juice, simply pour it in empty ice cube trays. Now, keep the trays into the freezer for about an hour, and you will soon notice that the juice has frozen and has taken the shape of ice cubes. Now, take out the cubes of the juice from the tray and place them in a plastic freezer bag. Store the bag in the freezer, and use the cubes of the juice whenever needed.
Bottled Lemon Juice
Buying bottled lemon juice available in the market has one advantage―they have a longer shelf life. This is because, they are processed, highly concentrated, and moreover, added with preservatives. Processing involves heating the concentrate briefly at a high temperature before finally bottling it out. All this helps in increasing the shelf life of the juice significantly. For instance, a sealed bottle of lemon juice can easily last for about a year without refrigeration. However, once it is opened, it needs to be refrigerated to prevent spoilage. Once it is refrigerated, it generally lasts for 6 months. Most commercially prepared bottles have printed 'best before' date, which usually indicates the shelf life of the juice.