The Complete Handbook of Horseradish Sauce

Chapter 1: Understanding Horseradish Sauce

Horseradish sauce is not a simple condiment. It is a carefully balanced emulsion of plant material, acid, oil, and water, whose primary sensory characteristic - the sharp, sinus-clearing heat - is a volatile compound that is created in one chemical reaction and destroyed by another. A jar of horseradish sauce is a snapshot of a chemical reaction in progress, and how you store, open, and serve it determines whether you experience that snapshot at its sharpest or as a flat, bitter afterthought.

At its core, horseradish sauce is a preparation made from the grated root of the plant Armoracia rusticana. The root itself is bland and woody for the most part. The heat you are familiar with does not exist in the intact root. It only appears when you cut, grate, or crush the root, which brings two compounds into contact that are kept separate in the living tissue. One is a glucosinolate called sinigrin, which is a sulfur-containing sugar molecule. The other is an enzyme called myrosinase. Once the cell walls are broken, the sinigrin and myrosinase mix, and the enzyme hydrolyzes the sinigrin into glucose, hydrogen sulfate, and a volatile isothiocyanate called allyl isothiocyanate (AITC) - the molecule responsible for horseradish's pungent heat. The reaction is fast; it begins within seconds of grating and is largely complete within a few minutes.

The volatility of AITC is not just a sensory detail; it is a storage, handling, and quality issue. AITC is a