In an email, Luc asks:
“I’ve been looking to find a conversion factor between whole and ground spices. I only keep whole spices in my kitchen. Recipes mostly call for ground. I think it would be a good idea to have a conversion factor for, let’s say, coriander and cumin. That would help me guess the other spices…”
The innovation of precise measurements for recipes was a fantastic thing. It allowed a whole new era of communication about how to prepare a dish that could be communicated from one person to another or from one person to a whole group of people. It has saved many a casserole, and, in many ways, has made cooking an easier thing.
Unfortunately, it gives a false illusion to people who are making food. Because 1/8tsp, the smallest measurement you’re likely to come across in a non-molecular-gastronomic recipe, is a relatively small measurement compared to the size of the dish, you are given the feeling that it means something very important. The more precise the measurement, the more weight you will give its significance compared to the rest of the recipe. The last thing anyone wants to do is add too much cumin to a recipe, thus spoiling all of the other fl avors, and with a tiny measurement like 1/8 tsp hanging around, you start to think that an extra 1/4 tsp of a spice will kill the flavor.
Much to the dismay to those of a scientific bent, the most important factor in “how much flavor you’ll be imparting to a dish” with spices isn’t the amount. Don’t get me wrong, adding a tablespoon where a teaspoon was requested will definitely increase the amount of flavor, but the freshness of the spice, the growing conditions, how long ago it was ground, and the variety all will affect the flavor more than just the amount. Put another way, a tablespoon of pre-ground, old, off-brand spice will not give as much flavor to a dish as a 1/2 tsp of freshly ground, quality, bloomed spice will.
Fortunately, you’ve already taken some good steps towards making sure that you give the food the flavor it needs: you’re using whole spices. Based on the previous paragraph, you can also presume that any recipe that you get from someone who used dried spices will not give you the proper measurements anyways. So you can start to see where I am going.
When I first got your question, I was very tempted to start writing about packing ratios and grind size, and I was going to get a big bag of whole spices and compare what happens if you grind a lot of it versus just a little at a time to see what happens. As I thought about it more, though, it seemed like that would ultimately be a waste of time.
Instead, let’s decide what’s the most useful aspect of the information from the recipes: the ratio. You want to know, more or less, how much of one spice to use instead of another. Of course, you also want to minimize waste, but we’ll get to that in a moment. We know that ground spices pack much better than whole spices, so we’ll assume that, when measured by the person who made the recipe, they are more or less the same amount of volume-to-weight ratio from spice to spice. In other words, 1/4 tsp of cumin is going to weigh half as much as 1/2 tsp of paprika if measured by the same person. It’s not going to be entirely true, but it’ll be true enough for our purposes.
So, from that, you know that if you weigh out your whole spices in such a way that the weights of the spices are proportional to the volume measurements from the original recipe, you’ll be okay.
As for the total amount of spice in a dish, I think, deep down, you already have a pretty good idea of what you need. It’s a rare dish (other than a curry, chili, or another spice-heavy dish) that would need more than a handful of whole spices in all. Remember that the quality of the spices that your market carries will greatly affect the flavor it imparts in the dish, so more important than the measurements is learning how your spices are. Once you grind them and are able to smell their potency, you are going to have a much better feel for how much to add to a dish.
The other thing about fresh spices versus old, ground spices is that the complex flavors are the ones that will be lost first with age and oxidation. This means adding a lot of an old, nasty spice will bring out a specific note of flavor that, in larger quantities, will not necessarily be pleasant. With the freshly ground, properly handled spices, you will get more nuance and more complex flavors even if you add “too much” to the food.
In other words, become one with your spices. Play with them, and don’t be afraid off adding too much or too little. If it’s a spicy, capsaicin-rich spice, and you have eaters who are fearful of spicy foods, lean towards adding too little instead of too much. Otherwise, you really do have a lot of play between underspiced and overspiced. It’s not a thin line, despite the illusion created by 1/8 tsp measurements, and it will really free you up when you know, in your heart instead of your brain, what kind of flavor the spices will add to your food.