How is mustard made ?

Dijon mustard is a blend of mustard seeds and verjuice. Verjuice is made of water, vinegar and salt.

The mustard seeds are soaked in verjuice, and then ground and finely sieved in order to separate the mustard from the bran.

The hot taste of mustard comes from seeds and is released when seeds are ground in the verjuice. Allyl is obtained from this step, giving its hot taste to mustard. Allyl is extremely volatile. It is better to keep mustard refrigerated to maintain its hot taste.