Spices also loose their flavor with age. Something that has been sitting in your spice cabinet for a couple of years will have little flavor left. The same applies for the use of fruit and vegetables. The brightest, plumpest, and juiciest should be chosen. Avoid fruit and vegetables with brown spots on the skin When using wine or beer, be sure it is of good quality.
Dry wines are better than sweet ones.
When you crush the mustard seed you release its volatile oils. It is at this point that it is the most pungent. If you don't believe me chew on a mustard seed or two. If you like your mustard this hot, refrigerate it after putting it into a clean sterile jar. Refrigeration will slow the decrease in pungency.