Onions have a fairly high water content so you can extract a large amount of juice from just one onion. Actually, there are not many nutrients contained in onion juice, but in many countries, this juice is considered a traditional medicine to treat hypertension, poor blood circulation, urinary tract infections, and colds. There are several ways to extract onion juice, such as using a grater, blender, or juicer.
Method 1 of 4: Preparing the Onions
Step 1. Peel the onions
Use a sharp serrated knife to cut off the root end of the onion (no more than 1 cm). Chop the onion until you reach the skin on the other side, but don't cut it all the way through. Grasp the part that is partially cut off and pull it down, towards the other end to remove some of the skin. Grasp the remaining skin with your thumb, index and middle finger and pull to remove the entire onion skin.
Step 2. Cut the other end
Use the same knife to cut the other end of the onion about 1 cm. This step will make it easier for you to chop the onions and is especially important if you're going to be using a blender or juice extractor.
If you want to use a grater, you don't need to do this step. Without cutting the other end of the onion, it makes it easier for you to grate the onion
Step 3. Wash the onions
Place the onions under warm running water from the tap to remove any remaining skin and dirt. Dry the onions with a clean paper towel.
Method 2 of 4: Using a Grate
Step 1. Place the grated cheese square in a shallow bowl or saucepan
You'll need a container that has sides, but the mouth of the container should be wide enough to fit a square cheese grater or coconut grater and at least one hand because you'll be grating the onions in the container.
Step 2. Grasp the top of the grater with one hand
Press the grater so that it is stable and does not slip when you start grating the onion.
Step 3. Rub the onion on the finely perforated part of the grater
Hold the end of the onion left intact with the other hand. Press the flat end (the part of the root cut off) against the finely perforated side of the grater. Move the onion up and down over the holes of the grater. Continue grating the onion until all the onions are used up.
Step 4. Place the strainer over a medium or large bowl
The bowl should have high sides with a mouth wide enough to accommodate the diameter of the sieve. If possible, overlap the strainer over the rim of the bowl. If the sieve is too small, you will have to hold it in by hand.
Step 5. Press the onion pulp through a sieve
Pour the onion pulp from the grater into a fine sieve. Use a spoon or rubber spatula to press down on the onion pulp so that the juices can flow into the bowl underneath while the pulp remains in the strainer. Continue this procedure until you have extracted most of the juice. Don't press too hard, as the onion pulp can pass through the sieve and fall into the bowl.
Step 6. Place the remaining onion pulp in the middle of a piece of cheesecloth, then bring the four ends together so that it wraps around the onion pulp
Squeeze the onion pulp to release any remaining juice into the second bowl. Continue this procedure until no more juice comes out.
Method 3 of 4: Using Blender
Step 1. Cut the onions
Use a sharp knife to cut the onion into medium-sized pieces. You don't need to chop the onions finely. If you're using a blender, small or medium chunks will be more efficient than large chunks.
Step 2. Put the onion pieces in the blender, then turn on the machine
Use medium-high speed to high and run the machine for about 1 minute, until the onions are a thick puree.
Step 3. Repeat this process as needed
Running the blender for 1 minute should be enough to make an onion puree, but every machine works differently. If you see that there are still large chunks of onion in the blender, turn off the engine, open the lid, and push the onion pieces against the knife with a rubber spatula. Put the lid back on, and run the engine at high speed at 30 second intervals until the whole onion is a fine pulp.
Step 4. Place the strainer over the bowl
Choose a strainer that is small enough to fit into the bowl, but also large enough to hang over the rim of the bowl. Otherwise, hold the strainer over the mouth of the bowl with one hand.
Step 5. Place a piece of cheesecloth/ cheesecloth in the colander
A thin cloth will make it easier for you to extract the juice and separate it from the onion pulp.
Step 6. Press the mashed onion through cheesecloth and a sieve
Pour the onions from the blender into the center of the cheesecloth. Use a spoon or rubber spatula to push the onion pulp through cheesecloth and a sieve so that the juices drain into the bowl. Continue this process until no more juice drips from the bottom of the strainer.
Method 4 of 4: Using a Juice Extractor
Step 1. Cut the onion into quarters
Whole onions will be too large for most juice extractors, but small pieces will be too small to press. Use a sharp knife to cut the onion lengthwise into quarters for best results.
Step 2. Choose the right type of device
Use an electric juice extractor with a feeding tube and a spout. Manual juice extractors, or devices operated by pressing a fruit or vegetable against a bulge to extract juice, are only effective for soft fruit types such as lemons, oranges, and limes. To extract juice from tough vegetables like onions, you'll need an electric juice extractor with a feeding tube that allows you to insert the chopped vegetables.
Step 3. Place the bowl under the spout
Some juice extractors come with a glass container to hold the juice. However, in most cases, you will need to place a bowl or glass under the spout before starting the extraction as the juice will flow through the spout during the process.
Step 4. Press each piece of onion into the filling tube
Wait for each chunk to finish extracting before you add another chunk. The juice will be filtered automatically through the spout while the dregs will be accommodated in another compartment. You no longer need to filter the resulting juice.
- Wash the grater, blender, or juice extractor thoroughly after using to extract the onion juice. Onions have a very strong odor and are not easily lost. You may have to soak the utensils in hot water and soap for a few minutes and scrub them to remove odors so they don't contaminate other foods.
- You can also pour soapy water into the juice extractor.
- Be careful not to get the onion juice in your eyes.
- Be careful when using a sharp knife so as not to injure you.