Editors’ Note: Nik Sharma’s new book, The The Flavor Equation: The Science of Great Cooking Explained in More Than 100 Essential Recipes, comes out in October 2020. You can pre-order it anywhere books are sold.
The polyphenols present in olive oil and mustard oil are phytonutrients, but they are also responsible for the bitter taste when these oils are used to prepare emulsions like mayonnaise. To solve this problem so I could include a recipe for a mustard oil mayonnaise in my book, The Flavor Equation, I found a way to extract the polyphenols. Reading through a research document about plant waste, I discovered that the polyphenols present in olive oil are highly soluble in water, and the solubility is at its maximum at the boiling point of water. In the absence of any emulsifiers, when mixed, water and oil eventually separate, and the water carries the bitter-tasting molecules away from the oil. This method works with mustard oil, too.
Make a little more debittered oil than you need for a specific recipe, so you don’t run out even if you lose some during the separation of the oil and water. Note that you while you can also combine the oil and water by shaking them in a sealed jar or using a countertop blender, you need to take extra care with those methods since the closed containers can build up steam during agitation, leading to explosive results.