Mustard

Ingredients ─────────── ...

Instructions ──────────── ...

Science ─────── From http://amazingribs.com/recipes/my_ingredients/zen_of_mustards.html:

Mustard's heat comes from oils released when the ground seed is mixed with 
liquid. The active ingredient is allyl isothiocyanate. It travels up the 
nose, and the really hot ones can make your eyes tear. Unlike chile pepper 
heat, which tends to stay in the mouth and builds cumulatively with each 
mouthful, mustard heat dissipates fairly quickly.

From https://en.wikipedia.org/wiki/Allyl_isothiocyanate:

Allyl isothiocyanate can be obtained from the seeds of black mustard 
(Brassica nigra) or brown Indian mustard (Brassica juncea). When these 
mustard seeds are broken, the enzyme myrosinase is released and acts on a 
glucosinolate known as sinigrin to give allyl isothiocyanate.

Allyl isothiocyanate serves the plant as a defense against herbivores; 
since it is harmful to the plant itself, it is stored in the harmless form 
of the glucosinolate, separate from the myrosinase enzyme. When an animal 
chews the plant, the allyl isothiocyanate is released, repelling the 
animal.

From https://en.wikipedia.org/wiki/Myrosinase:

At neutral pH, the primary product is the isothiocyanate. Under acidic 
conditions (pH < 3), and in the presence of ferrous ions or epithiospecifer 
proteins, the formation of nitriles is favored instead [2][6].

Ascorbate (vitamin C) is a known cofactor of myrosinase, serving as a base 
catalyst in glucosinolate hydrolysis [1,7].  For example, myrosinase 
isolated from daikon (Raphanus sativus) demonstrated an increase in Vmax 
from 2.06 µmol/min per mg of protein to 280 µmol/min per mg of protein on 
the substrate, allyl glucosinolate (sinigrin) when in the presence of 500 
µM ascorbate [4].

From Eylen, Hendrickx, Van Loey. Food Chem 97:2:263−271 (2006):

In this study, the temperature and pressure stability of partially purified 
myrosinase from mustard seeds (Sinapis alba) was studied in a model system.  
Temperature inactivation started at 60°C and the inactivation kinetics were 
studied in detail between 65°C and 75°C.

All glucosinolate-containing-plants also contain myrosinase (thioglucoside 
glucohydrolase EC 3.2.1.147, formerly EC 3.2.3.1). This enzyme hydrolyzes 
glucosinolates to form an aglucone and d-glucose. The aglucone is unstable 
and spontaneously decomposes into nitriles, thiocyanates, isothiocyanates 
or indoles depending on the side chain, pH, presence of ferrous ions and 
proteins such as epithiospecifier protein.