The Science and Health Benefits of Horseradish
Richard AIken, MD, PhD
Homegrown horseradish has a clear, fresh taste and packs more flavor than the store-bought variety. It also ranks in the top five easiest-to-grow edible plants because it thrives in a variety of conditions. Horseradish contains strong antioxidants and is being investigated as a source of anti-cancer containing components as explained below.
Homemade prepared horseradish is about twice as strong in flavor as store-bought versions, and lasts about 3 to 4 weeks in the refrigerator.
o 1 cup peeled and cubed horseradish root
o 3/4 cup white vinegar
o Salt to taste (typically ¼ teaspoon or less)
Process the root by grating by hand or in a food processor or blender. If done by hand, be very careful not to directly inhale volatile isothiocynates – they are hazardous to mucosal membranes.
Let the grated horseradish sit for about 3 minutes, then add the vinegar and mix. See the Science section below for more details of the chemical transformations and the reason for the delay in adding the acidic medium.
Then just seal it up in an airtight container and keep it chilled. It’ll keep at least a few weeks, if not longer, in the refrigerator.
A variation of this horseradish sauce uses lemons instead of the vinegar, known in Germany as Tafelmeerrettich. For one cup of horseradish use the juice of one whole lemon. Other variation include mixing in grated garlic (Russian) or grated beetroot (known as khreyn in Jewish Passover).
Horseradish peroxidase is being studied for its anti-cancer properties . Horseradish contains other glucosinolates which are strong antioxidants (Bonifert, G., Folkes, L., Gmeiner, C., Dachs, G., & Spadiut, O. (2016). Recombinant horseradish peroxidase variants for targeted cancer treatment. Cancer Medicine, 5(6), 1194–1203. doi:10.1002/cam4.668).
When horseradish cells are damaged by cutting, grating, or chewing, enzymes convert the glucosinolate sinigrin to allyl isothiocyanate (mustard oil) by the enzyme horseradish peroxidase. The plant uses isothiocyanates as a defense against attack by predators. The allyl isothiocyanate apparently decomposes quickly; this decomposition can be slowed significantly by an acidic medium.
There is an optimal time for the formation of the isothiocynate beyond which the decomposition becomes significant. Application of an acidic medium, such as from that from acidic acid (vinegar) or citric acid (lemons), effectively quenches the decomposition (Pecháček, R., Velíšek, J., & Hrabcová, H. (1997). Decomposition Products of Allyl Isothiocyanate in Aqueous Solutions. Journal of Agricultural and Food Chemistry, 45(12), 4584–4588. doi:10.1021/jf970316z ).