You might be surprised to learn that grape juice should not be left on the counter: even if it has been pasteurized, it needs to be kept in the fridge. If it is left out for more than two hours, it is no longer safe to drink, according to FDA guidelines. Unpasteurized grape juice needs to be kept in the fridge at all times.
Those guidelines might seem quite strict, and some people may not follow them. However, if you are interested in food safety, know that it is important to keep your juice refrigerated.
What Happens If I Don’t Refrigerate Grape Juice?
If you don’t refrigerate grape juice, bacteria will start to breed in the juice. Pasteurized juice has been heated to reduce the speed with which this happens, but it is still meant to be kept in the fridge. If left out, bacteria will start to appear in the juice, making it unsafe to drink.
If you drink grape juice that has been kept out of the fridge, it could make you sick. Harmful bacteria may have started to spread throughout the liquid, and you might notice that the juice tastes sour or unpleasant.
How Long Will Grape Juice Last Unrefrigerated?
Pasteurized grape juice may last for a couple of hours if unrefrigerated, but it should not be left out overnight or even for half a day at room temperature. Bacteria could start to spread through the juice.
Unpasteurized grape juice should not be left out of the fridge at all. Because it has not been heat treated to begin with, there may be some bacteria in it even when you buy it.
Keeping it in the fridge will slow down the spread of this bacteria, but if you leave the juice out, they will quickly multiply and make the juice unsafe to drink.
Many people do leave juice out for more than two hours without suffering from any ill effects, but it is important to keep it in the fridge and follow the FDA guidelines. Juice is not meant to be left at room temperature.
How Long Will Grape Juice Last After Opening?
This depends on the type of grape juice that you buy. There should be a recommendation on the bottle, because different processes will offer different preservation periods.
However, most commercial grape juice should last for around seven to ten days if stored in the fridge with a lid on the container to reduce airflow. Grape juice has a lot of sugar in it, which acts as a natural preservative and keeps the juice fresh.
If you buy non-pasteurized grape juice or you make your own at home, do not expect it to last for this long. Most homemade grape juice will need to be used up within a couple of days of making it.
This is especially true if you are unable to put it in a sterile container. Make sure that whatever container you use has been thoroughly washed with hot, soapy water.
If You Leave Grape Juice Out, Will It Turn To Wine?
Most of the time, grape juice that has been left out will not turn to wine, because it has not been exposed to yeast. You should not leave grape juice out in an attempt to get wine.
In some circumstances however, grape juice could turn into wine if it is left out of the fridge and exposed to air. How would this happen? As I mentioned, in order to turn into wine, grape juice must have yeast added to it.
This could, in theory, occur in your kitchen for some other reason. This is because there are many sources of wild yeast in the environment, and if any happens to drift into your grape juice, it could start the fermentation process.
However, this is not something that you should attempt in order to make your grape juice turn into wine. You have no way of telling where the wild yeast has come from, and it will not make delicious wine from your grape juice.
Making wine must be done in controlled conditions, using the correct kind of yeast strain. You should not use wild yeast if you want to make wine; a domesticated yeast that has been bred especially for that purpose is needed instead.
How To Tell If Grape Juice Is Bad
You can tell if grape juice has gone bad in several different ways.
Look at the juice
Start by pouring a small amount into a glass. Inspect the juice for any signs of mold floating on the surface of the liquid. You can also inspect the mouth of the bottle/carton for mold spots.
Smell the juice
If you cannot see anything, swirl the grape juice around and smell it. Does it smell sweet and normal, or is there a strange odor? Bacterial infections may cause an unusual scent in the juice.
Taste a small amount
Next, if you are still unsure, taste a small amount of the grape juice. It may taste sour or musty if it has gone off. It might also have developed a flavor slightly like wine if it has begun to ferment.
Fermentation often causes the juice to be a little fizzy, too.
Do not drink grape juice that looks, smells, or tastes odd. If all of your senses tell you that the grape juice is safe, you may decide to take the risk, but be aware that it could still make you sick.
Avoid the uncertainty by always keeping your grape juice in the fridge and making sure that you use it up within the time period recommended on the container.