I was looking for a simple recipe to illustrate the power and relevance of chirality to my students in chemistry. R and S carvone are mirror images. They are the essential oils found in spearmint and caraway. Interestingly, the connectivity of the molecules is the same, simply the three dimensional arrangement around one carbon atom differs. Yet the flavor difference is powerful. These molecules have the same physical and chemical properties, with the exception of how they rotate plane-polarized light, and the way they interact with other chiral molecules. It so happens that most of our taste receptors are chiral, and they recognize this pair of isomers differently. Spearmint gum is easy to find, and these snacks may provide an interesting, exotic flavor for those unfamiliar with caraway.
1.25 cup whole wheat flour
1.5 tbsp sugar
0.75 tsp salt
0.25 tsp paprika
0.5 tbsp caraway seeds
4 tbsp butter
0.25 cup water
Add all dry ingredients into a food processor, with exception of the caraway.
Pulse with the diced butter until it's incorporated into coarse crumbs.
Add the water until a ball begins to form. Add caraway seeds and stir in briefly.
Preheat oven to 400F, line a baking sheet with parchment paper. Roll out half of the dough into an even, 1mm-thick layer.
Cut with a pizza cutter and bake for 7 minutes. Cool in cookie pans.