Roasting spices is not a very common technique in this country, but is used with great regularity in many cultures around the world. Dry roasting your spices is a simple way to bring an almost magical flavor to your cooking. Best of all, you don't need to be a culinary trained chef to get the most out of roasting spices and in fact, you'll find that it is as much an art as it is a science.
You'll have to train your senses and develop a good understanding of the ideal timing, but once you get it down you'll be amazed at the difference. As you master this skill, you'll find that the proper use of heat and the right amount of time will draw out the aroma while releasing the oils that are trapped inside the raw seeds, chiles and peppercorns. While you can certainly enhance the flavor, you've got to be careful with some spices, as you can actually alter their flavor by over roasting as well.
So, while it's part art, you will also need to take a methodical approach to this – the science. What about the meal you're preparing and the spices you're using? Are you cooking low and slow or fast and hot? Will your tubers and root vegetables benefit from a deep roast or are you doing a quick stir fry? Spices used in slower cooked dishes may have time to allow their seeds to soften and have may benefit from the slower release of the flavors. On the other hand, dry roasting spices for a sauté or stir fry provides an explosion of additional flavor that can send your dish form good to amazing!
What Happens During Roasting?
When you're roasting spices you are releasing the oils of the spices. Spices have two primary types of oils – one is the non-volatile oils which are a series of oleoresins which provide the aroma of the spice. The second is the volatile or essential oils which provide the flavor of the spice. It is most common to roast whole spices (instead of ground) as these better retain their natural oils making them better suited to dry roasting.
How to Roast Spices
I prefer using a heavier small pan or skillet and cast iron works very well, as does a wok. Now, part of the art is that there is no one best way to roast spices – you'll have some choices to make the first couple of times you roast and then as you gain experience you'll develop the roasting philosophy that works best for you.
Some home chefs prefer preheating their pan while others choose to start with a cold pan. I fall in the camp of pre-heating. There are also several schools of thought on using a little oil when you roast your spices and others prefer to dry roast. I lean more towards dry roasting most of the time. No matter which combination of techniques becomes your own unique style, the goal of roasting is it to enhance the character of the spice by releasing the spice's deeper flavor.
Using a heavy skillet spreads the heat evenly and keeps the temperature consistent. Roasting is not something that you want to rush, so avoid using high heat and keep in mind "low and slow". I like to use the heat on low or low-medium. You want to heat your spices slowly so that they warm deep into the center of the spice while not burning the outer edges.
When You're Done Roasting
As soon as you feel that you're done roasting your spices you'll want to remove them from the heat and put them on a plate to cool. Leaving them in the pan and just removing from the heat source will allow your spices to continue cooking and often leads to burning or scorching (negating all your work).
Let your spices cool completely and then grind them either with either a mortar and pestle or with an electric coffee or spice grinder. Roasted spices tend to be easier to grind than unroasted spices. You'll get maximum flavor if you use your spices the same day that you roast them (after allowing them to properly cool) but you can also store them in an air tight jar for several weeks before using them without much degradation. If I go this route I like to leave the whole roasted seed intact and then grind as needed for maximum flavor.
Other Things to Consider
There is another way to roast spices, although it is not near as efficient and a whole lot less fun. This method consists of roasting your spices in the oven on a cookie sheet or a stone wear baking sheet. This is less efficient, as you have to pre-heat the oven and it will also be harder to gauge when the spices are fully roasted. And less fun, as it is much more enjoyable to move the spices around with your wooden spoon and soak in the amazing aroma as the oils are released!
You don't have to only roast one spice at a time if you are using whole seeds for one particular recipe or homemade seasoning blend. But you should be aware that not all spices roast in the same time period and since, especially at first, you're relying on the aroma to help you determine when the spices are done roasting you should stick to roast your spices separately.
As you gain experience you may want to experiment further by roasting your "blend" of spices together. After you've gained the knowledge of approximately how long each spice takes to roast you can add the various spices at different times so that they are all finished roasting at the same time. Be aware that this takes a good deal of practice to get the timing down just right. Also if you're going to add any ground spices to this cocktail of roasting spices be sure to add them at the very end, as ground spices have less volatile and non-volatile oils and only need seconds to roast.
This is an advanced technique for sure, but it is also the natural evolution as you become more familiar with how amazing spices can be when used to their fullest capability.
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How to Store Spices
Working with Whole Spices
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