The short answer: to make bright green basil oil, blanch 60 g basil leaves in boiling water for 10 to 15 seconds, cool them in ice water and squeeze them dry. Blend with 240 ml (1 cup) neutral oil for 1 to 2 minutes, then let it drip through a coffee filter. Keep it in the fridge and use it within 4 days, or freeze it.
Basil oil is summer in a squeeze bottle. A few drops on a tomato salad, soup or a plate of pasta look like a restaurant dish and taste of fresh basil. Done the quick way, it stays bright green and sweet. Done the wrong way, it turns brown, murky or bitter within a day. The difference comes down to three small steps: blanch, use the right oil, and strain slowly.
| At a glance | |
|---|---|
| Time | 15 minutes, plus 30 minutes to drip |
| Makes | About 200 ml |
| Ratio | 60 g basil leaves to 240 ml neutral oil |
| Keeps | 4 days in the fridge, 3 months frozen |
Ingredients
- 60 g (about 2 packed cups) fresh basil leaves, stems removed
- 240 ml (1 cup) neutral oil, such as sunflower, rapeseed or grapeseed
- A pinch of salt
- A bowl of ice water
- A coffee filter or a fine sieve lined with muslin
Why a neutral oil: extra virgin olive oil can turn bitter when you blend it hard in a fast blender. A neutral oil keeps the taste sweet and lets the basil lead. If you want olive oil flavour, use half neutral oil and half mild olive oil, or stir a little extra virgin into the finished oil.
How to make basil oil
- Blanch. Drop the basil into boiling water for 10 to 15 seconds, until bright green and just wilted.
- Shock. Lift it straight into the ice water with a slotted spoon. Leave it for 30 seconds.
- Squeeze dry. Squeeze the basil hard in a clean tea towel. Water left in the leaves makes the oil cloudy and shortens its life.
- Blend. Blend the basil with the oil and salt on full speed for 1 to 2 minutes, until smooth and deep green.
- Drip. Pour it into a coffee filter set over a jar. Let it drip for 30 minutes. Do not press it, or the oil turns murky.
- Chill. Pour the clear green oil into a clean bottle and keep it in the fridge.
Why basil oil turns brown or bitter
| Problem | Cause | Fix |
|---|---|---|
| Turns brown or dull | Leaves not blanched | Blanch 10 to 15 seconds, then ice water |
| Tastes bitter | Extra virgin oil blended hard | Use a neutral oil |
| Cloudy | Wet leaves, or the filter was pressed | Squeeze dry, let it drip |
| Tastes of cooked greens | Blanched too long | 15 seconds at most |
Blanching is the key step. A short dip in boiling water stops cut leaves from browning and sets the colour. Longer, and the basil cooks and tastes of spinach.
A slow-infused version with dried basil
A dried basil oil is a different thing: golden, gentle and savoury rather than green. It suits roasting, dressings and bread dipping. With the NOIDS Herb Lab:
- Put 200 ml olive oil and 3 tablespoons dried basil into the Glass. Stay under the MAX mark.
- Cover with the Dish Lid and place the Glass in the Main Body.
- Turn the Rotary Control to Oil. The cycle holds 100 °C (212 °F) for about 120 to 180 minutes, then cools by itself.
- Strain through the Filter Set into a clean bottle.
Our guides to infused olive oil and rosemary-infused olive oil use the same method with other herbs.
Other soft herbs to try
The same blanch, blend and drip method works with most soft green herbs. Parsley makes a deep green, grassy oil that suits fish and potatoes. Chives give a mild onion flavour, lovely on eggs and soups. Coriander is bright and fresh for tacos and curries. Tarragon brings a soft anise note for chicken. Use the same amounts: 60 g leaves to 240 ml oil. Skip blanching for chives, as they are delicate. Woody herbs like rosemary and thyme are better slow-infused than blended.
How to use basil oil
- Drizzle over burrata or mozzarella with tomatoes.
- Swirl into tomato soup or chilled gazpacho.
- Finish pasta, risotto or grilled fish.
- Mix with lemon juice for a quick green dressing.
- Spoon over grilled vegetables or a plate of hummus.
How to store basil oil safely
- Fresh basil oil: keep it in the fridge and use it within 4 days. Fresh herbs in oil can grow harmful bacteria at room temperature, without any change in smell or taste. University food-safety guidance gives the same advice for all fresh herbs in oil.
- Freezer: pour it into an ice-cube tray, freeze, then keep the cubes in a bag for up to 3 months.
- Dried basil oil: strained, keep it in the fridge and use it within 1 month. Penn State Extension allows up to 3 months; we use the shorter time.
- Cold oil turns thick and cloudy. Let it sit out for 10 minutes before use.
Questions
How do I keep basil oil green?
Blanch the leaves for 10 seconds, cool them in ice water and squeeze them dry before blending. That sets the colour.
Why is my basil oil bitter?
Extra virgin olive oil can turn bitter when blended hard. Use a neutral oil like sunflower or grapeseed instead.
How long does basil oil last?
Fresh basil oil: 4 days in the fridge, or 3 months frozen in cubes. Strained dried basil oil: 1 month in the fridge. Never keep either at room temperature.
Can I use dried basil?
Yes, but it makes a golden, savoury oil rather than a green one. Infuse it slowly, strain it, then keep it in the fridge and use it within 1 month.
Do I have to blanch the basil?
For a bright green oil, yes. Unblanched basil oil turns dull and brownish within a day.
