How to make Wasabi Oil
Wasabi oil is normally just a relabeled bottle of Mustard oil mixed with other oil to reduce the mustard taste.
There are a number of recipes on the internet that use mirin, mustard oil, sugar and wasabi powder.
I have found that this just gives a sweet very weak tasting oil with not a lot of flavour.
There are also some products claiming to be made from crushing Wasabi seeds. The number of Wasabi seeds to produce even a small amount of oil (a teaspoon) makes this claim laughable. The oil might be from crushing seeds, but the seeds come from the mustard plant.
See the article "The difference between Wasabi and Mustard".
The recipe I will give you below is the one that we used a decade or more ago when we made this product commercially.
What is Wasabi Oil?
Wasabia japonica is part of the Brassicaceae family, which also contains horseradish, radishes, and mustard. They all share the same heat-producing chemical compound, allyl isothiocyanate, which is only triggered when its cells are broken down, i.e., by crushing mustard seeds, or grating Wasabia japonica rhizome (swollen stem) or horseradish root.
The compound is a volatile one that evaporates quickly, which is why we feel the heat of Wasabia japonica, horseradish, and mustard in our sinuses. It’s also more water-soluble than the oily heat-producing compounds found in chilies, which is why chili heat lingers even after a glass of water, but wasabi and horseradish heat fades quickly from the tongue.
Wasabi heat and flavor also break down quickly on the plate. Fresh-grated wasabi hits peak pungency after about five or ten minutes, and loses most of that heat after fifteen or twenty. For this reason, wasabi products are often either dehydrated (powdered), or preserved in an oily paste.
But real Wasabia japonica products are tough to come by, and rather expensive, because the Wasabia japonica plant is difficult to cultivate. Wasabia japonica originally only grew in cool Japanese mountain streams, protected from the sun by the shade of overhanging trees. It sounds idyllic; it’s also very specific in its demands.
Wasabi oil is really a infused oil, where the wasabi flavour is infused into the carrier oil by immersion. So in theory all you need to do to make wasabi oil is to add a wasabi rhizome to oil and let it soak.
The problem is that this simple method is it can produce botulism in the infused oil.
Making an infused oil
Begin by selecting a good quality olive or other vegetable oil. Thoroughly wash and dry the fresh flavoring ingredients. Garlic should be finely chopped or crushed. Add the cleaned ingredients to a clean container.
Choose a vinegar with four to five percent acidity. In a pot, heat vinegar to near boiling (190°F). Pour the hot vinegar over the infusion ingredients, cover, and cool. Once the mixture has reached room temperature, add your oil and replace the cover.
You need enough vinegar so that the finished product has a pH of 4.6 or lower. This will keep botulism bacteria from growing. Test the pH with a pH meter for food safety.
Storage
Although we do not advise making oil infusions with fresh additives at home, refrigerating this kind of oil infusion immediately after preparation will reduce your risk. Refrigeration will slow bacteria growth. Refrigeration will also slow the process by which oils go rancid. After one month, the number of bacteria in the product can become a food-safety hazard and it should be thrown away.
Acidified garlic, vegetables, and/or herbs in oil should be refrigerated. Do not store for more than one month. After one month, throw away any unused oil.
See https://extension.umaine.edu/publications/4385e/ for more information.
Making your Wasabi Oil
This is what we did to make the Namida Wasabi Oil
- Firstly you need a Neutral Oil
- Then you need Namida 100% Pure Wasabia japonica powder
- A tiny amount of cold water (preferably distilled).
- A Stainless Steel pot to mix the mixture in
- A Stainless Steel stirrer (a big spoon).
- Stainless Steel or Plastic Funnel (large one)
- Coffee Filter Papers
- Bottles and caps for the Wasabi Oil
Quantities required
- 1 litre (33.8 us fluid oz)
- 25g -> 50g Namida 100% Pure Wasabia japonica powder (dependent on taste)
- A small amount of cold distilled water - just enough to turn the Namida 100% Pure Wasabia japonica powder into a very firm paste. You know when you have added just enough as the colour changes to a darker green.
Neutral Oil
A neutral oil simply refers to the flavour. Olive oil, for example, is not neutral, it brings a distinct range of flavours to a dish. Grapeseed oil is considered one of the most neutral oils. It is nearly flavourless and can be used for frying, making herb oils, and other situations where you may not want any noticeable flavour from the oil medium.
Oils like sesame oil, chili oil, and walnut oil are decidedly not neutral. On the other end, oils like canola oil and grapeseed oil are neutral. Close to neutral, there are very mildly-flavoured oils like peanut oil. (Note that there's also strongly flavoured peanut oil, but "plain" peanut oil is very mild.) Somewhere more in the middle there are things like olive oil, which has some flavour but isn't overwhelmingly strong.
Method
1. Mix the Namida powder and cold distilled water together to make a very firm paste. Use the minimum amount of water.
2. Cover the paste with plastic film and put aside for 5 minutes for the flavour to activate.
3. Put the oil into the stainless stell pot.
4. After 5 minutes unwrap the firm paste and drop it immediately into the oil.
5. Start stirring the mixture immediately and break the wasabi ball up into very small pieces.
6. Stop stirring place stainless pot into the refrigerator and allow the wasabi to settle.
7. Leave in refrigerator for at least 24 hours.
8. Taste test the oil. If there is not enough flavour for you then add more wasabi paste (as above) and add it to the mix.
9. Re-stir and put it back in the refrigerator. (We used to use 50gms per litre and it really tasted like Wasabi).
10. When you have the taste you want then put a coffee filter into the funnel and slowly pour the Wasabi oil through it into a cleaned and sterilised bottle.
11. If the oil in the bottle looks cloudy then allow it to settle and then re-filter it into another clean bottle.
12. Put the cap on it and store it in the refrigerator until required. Ours lasted more than 24 months when stored like this.
Do not add the powder directly to the oil as this will not give you the wasabi flavour you want. The flavour is ONLY generated when water is added to the powder and then it is allowed to sit for 5 minutes. (See this video for more details.)
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