On Temperature; Blooming and Browning

This post is dedicated to my friend who set off the fire alarm burning spices on the first day of PhD :)

A lot of novice cooks have ingrained in them that high heat is the pinnacle of good cooking. This idea is all over pop cooking imagery: from depications of cooking Chinese food with sky-high flames, searing a steak on a ripping hot pan, Gordon Ramsay’s Hell’s Kitchen, and even Burger King’s “flame broiled Whopper.” When thinking of good cooking, the image of perfectly seared and browned meat comes to mind. As such, many cooks tend fry their spices and aromatics, such as garlic, at very high temperature, thinking that this is what best releases their flavor. The reality is that in most applications, a moderate temperature best helps food develop their flavors and prevents bitter notes from arising.

This post will focus specifically temperature control when it comes to aromatics (think garlic, ginger, onions) and spices (e.g. sichuan peppercorn, star anise, etc.). We’ll discuss the difference between blooming and browning aromatics/spices, and what (both good and bad) flavors arise in these situations. Lastly, we’ll look at some examples in which we might want a very hot vs less hot pan, and talk about how to sautee aromatics and spices in these cases. We’ll consider garlic as a running example, since it’s a common aromatic used in a variety of cuisines.

Aside: a note on heat transfer

Before diving into the details, I want to distinguish between “energy transfer” and “temperature.” The goal in cooking is to transfer heat (energy) to foods, which heats them up. Energy transfer is proportional to temperature difference multiplied by duration. So if you put a piece of food on a super hot pan for 2 seconds, it might not burn because not that much energy has been transferred to it, but if you leave it for 10 more seconds, it could potentially burn extremely fast, especially as the water in the food gets boiled off. I’ll often talk about things burning at high temperatures, but it’s important to remember that just because your pan is extremely hot, that doesn’t mean that your food will necessarily burn. If your food has high water content or if you only leave it in the pan at that temperature for a very short period of time, it will be safe from burning. This is also why we need a pan to be super hot when searing a steak; steak has a higher water content which cools down the pan quickly. We need the surface of the pan to be very hot, so we need the pan to be very hot to begin with so that it is still hot enough even after it cools.

What is blooming?

Blooming is the extraction of oil-soluble compounds from foods. Many aromatics and spices have flavor compounds that dissolve in oil, and hence frying extracts these flavors into the oil and spreads them out throughout the dish. For example, if you’re making a garlic mashed potato, you want a light garlic flavor throughout the dish; it would be bad if, for example, you just had chunks of garlic in the dish, and little-to-no garlic flavor outside of those. In this sense, oil (generally, fats) is the vehicle through which you transport these flavor compounds throughout the dish so that they don’t get stuck in individual chunks of garlic or spice.

Now what is browning?

If you fry the garlic at a higher temperature, it will eventually turn brown as proteins undergo the maillard reaction and sugars caramelize. This adds a more “nutty” or “caramelized” flavor that is also desirable, depending on the context. There isn’t a “better or worse” between browned vs un-browned garlic, it just depends on whether you want that roasted flavor or not. For example, in a mashed potato dish, you might prefer a very light garlic flavor in the background, as opposed to a stronger, roasted-garlic flavor, but this is up to preference and context. Note that we do need to fry the garlic a bit in order to get rid of the strong, raw garlic flavor, but garlic doesn’t need to be browned in order to achieve that.

On that note, let’s dive deeper into the chemistry of garlic. Raw garlic contains a sulfur-based compound called alliin. When garlic is chopped/crushed, the enzeme alliinase is released and converts alliin to allicin. Allicin is very sharp and volatile and gives that pungent, burning flavor that scares away vampires. There are some other compounds as well that have harsh flavors (diallyl disulfide, methyl allyl trisulfide; frankly I don’t really know the exact chemistry behind these, but just know that they are volatile sulfur compounds). When you start to bloom garlic (around 235F, notably higher than the boiling point of water), allicin decomposes into milder and more stable sulfur compounds that are more savory and less sharp, and these compounds get dissolved into oil (or something like butter) and can be spread throughout the dish. At this point, you’ve gotten rid of that harsh garlic flavor, but the garlic is not necessarily browned yet. If you keep heating up the garlic (higher than 300F), sugars caramelize and proteins undergo the maillard reaction, which creates even more nutty, roasted tones.

Here is a brief “timeline” of garlic:

• Raw garlic: creates allicin when cut. Sharp, pungent, “raw-garlic” flavor.
• Bloomed garlic (around 235F): allicin gets converted into savory and softer tones, and these compounds are dissolved into oil
• Roasted garlic (higher than ~300F): maillard reaction occurs and caramelization accelerates, there is visually a lot of browning
• Burnt garlic (around ~350F): minced garlic starts to burn. Large pieces of garlic might last longer if they have high water content.

Now we know some of the chemistry, the question remains as to how this translates into good cooking principles. How hot do we want our pan to be in order to most effectively extract out those garlic flavors?

Consider this example: the smoking point of canola oil is 400F (for olive oil it is 375F). Say you’re making a pasta sauce and you want to sautee some garlic to extract its flavors before adding in tomatoes. You don’t want your pan to be so hot so that as soon as you put in oil, it starts smoking immediately, since that means the pan is way above 400F. If you toss in your minced garlic, it will burn extremely fast. Even if you somehow don’t burn the garlic, having the pan so hot is counter-productive; since you want to dissolve flavor compounds into the oil, you want the garlic in the oil for a longer duration, NOT necessarily at a higher temperature. Having a super hot pan to extract the garlic flavors is completely pointless and only increases the risk of burning aromatics.

Of course, there are many cases in which you might want a searing hot pan (e.g., stir-frying vegetables, making steak). We’ll discuss below how to reconcile this with high temperature. Before diving into more examples, here is a nifty infographic I made with some helpful temperatures.

A few guiding principles and questions we can gather:

• The temperature we want for a steak or stir fry is way above the smoking point of oil. How can we possibly reach that temperature without the oil smoking and burning?
• Once we get the pan that hot, is it still possible to add in aromatics without it burning? What about spices?
• Spices tend to burn much faster than aromatics (mostly because they don’t have much water)

To answer these questions and explore our main concepts further, let’s look at some concepts/examples. In these examples, an important theme will be the order in which we add ingredients. For instance, if you’re making a steak, you obviously need to sear the meat first before adding garlic, since the maillard reaction happens at 300F+, and a prolonged exposure to this heat will dry out garlic and burn it.

If Oil Smokes at 400F, how do I get the pan to 500F? Example: steak

A lot of amateur cooks think that you should first put oil into the pan, and then heat up the pan. This is wrong if you are cooking something that requires a hot pan, like steak, since the oil will smoke before the pan gets to temperature. Instead, what you do is heat up the pan by itself first, and once it is hot enough, you add in the oil quickly, and then immediately add the steak (or whatever ingredient you’re using). Remember that heat transfer is proportional to temperature difference, multiplied by duration. If you put in the oil only for a second, it won’t get up to smoking temperature. Then, once you put the cold steak on the oil, the meat will start frying (say at 325F), but the oil will never get up to its smoking temperature (400F). If you wait too long after adding oil, it will start to smoke, which adds off-flavors.

Tomato Pasta Sauce

The first step is often to sautee aromatics (say garlic, onion) in order to extract their flavors into the oil, allowing them to infuse evenly throughout the sauce. As discussed above, this doesn’t require a high temperature. You just want to slowly fry the aromatics and dissolve the oil-soluble compounds. Since you won’t be browning meats or anything like that, there is no need for a high temperature.

Making a Sichuan Peppercorn/Chili Pepper Oil

According to the infographic, spices start to scorch around 300F. You definitely don’t want a smoking hot oil for this, otherwise your spices will burn immediately. Bloom them at a lower temperature, around 250F, until they are fragrant. Your oil might change colors as oil soluble compounds dissolve. Resist the temptation to increase the heat, thinking that higher heat will brown them and enhance their flavor! Browning is mostly for things like meats, and browning spices means that they are burning, which adds bitter flavors.

Stir-frying vegetables with garlic (Chinese style)

Stir frying vegetables requires a high temperature because vegetables contain a lot of water. Similarly to steak, if your wok is too cold, you will stir fry briefly, but after the wok cools, you will basically start to boil the vegetables, which isn’t good. What you do here is heat up the wok very hot, add in oil quickly, and add in your garlic briefly. The water in the garlic will prevent it from burning instantly. Then, after blooming quickly, add in the vegetables, which will release water and cool down the garlic so that it doesn’t burn. The temperature of the wok will now ideally be around say 260F, which is above the boiling point of water (the sizzling in the pan is water vaporizing), but under 300F, which is the temperature at which garlic starts to brown and burn. Speed is of the essence here; if you wait too long between heating up the pan, adding oil, garlic, and vegetables, your oil might start to smoke and your garlic might burn.

Braising Pork

Say we want to brown/fry some short ribs, add in ginger/garlic/scallion, and bloom some spices (star anise, peppercorns) in a wok before we add in sauces/water to braise. Quiz: in what order do we add these ingredients? (for example, do we bloom the aromatics first, then add in the meat, and lastly add the spices?)

I think the correct choice here is definitely brown the meat first, add aromatics, then spices. We want to first brown the meat, which happens at temperatures upwards of 300F, and can take a while. If we had added in the aromatics first, then by the time the meat is browned, the aromatics would be dangerously close to burning (or already burnt). The same logic goes for the spices. Hence, its best to brown the meat first. Even after its browned, the wok will still definitely be hot enough to bloom the aromatics (though I would reduce the heat a little). Then, since spices burn the fastest (due to low water content), I would add them in after the aromatics are halfway bloomed.

Note that this order is different from stir frying vegetables, where we had to add in the garlic before the vegetables. This is because the meat (like short ribs) doesn’t have a very high water content after we’ve been frying it for a while, so the temperature of the wok will still be hot enough to bloom the garlic. In the case of vegetables, if you put in the vegetables first, then the wok cools down quite a bit and hence blooming isn’t as effective. There are some powerful stoves though that can keep the wok very hot even while stir frying vegetables; for those, you could add in the garlic second, though you would probably need to add some additional oil so that the garlic flavors can infuse into it.