Why Steam?

It’s a long story that starts over 5,000 years ago. Steam cooking has persisted across cuisines, cultures, and technological revolutions. Why? Because adding steam to the cooking process can be both practical and downright delicious.

Adding steam can speed up cooking, it can keep your proteins juicy and your vegetables more vibrant, and a blast of steam at the beginning of baking is critical for producing big, airy, crusty loaves of bread. But understanding the role of steam in cooking is more complex – and more fascinating – than just a list of bullet points.

But before we go further, let’s explain what we mean when we say “steam.” If you’re picturing a boiling pan of water with some broccoli suspended above it, that’s only a small part of the story.

Simply put, food is mostly water. When you put your food in a traditional oven, it’s cooking in a hot, dry environment. The water in the food gets driven off, carrying flavor away with it, and leaving your food dry.

But air can only hold so much water. If we saturate the air with humidity by generating steam, the water content of your food has nowhere to go. It stays put, keeping your vegetables vibrant and your meats juicy.

It’s important to note that steam doesn’t just mean “steam.” The Anova Precision Oven lets you control the level of steam or humidity independently from temperature. On a stovetop steamer, you get one setting: full steam at 212°F / 100°C. But with the Precision Oven, you can add as little or as much humidity as you like over the full temperature range of the oven.

So, just like sous vide is not the same as boil-in-a-bag, cooking with steam is not the same as stovetop steaming.

Cook a Little Bit Faster Now

You likely have some intuition already for how steam can speed up cooking. So, let’s do a thought experiment!

Imagine (but please don’t try!) putting your hand in a 300°F dry oven. After a minute it’ll get uncomfortable, but otherwise, you’re fine. Now, (and definitely don’t do this) imagine (but again, don’t try) placing your hand above a pot of vigorously boiling water. Within a second, your reflexes will rightly yank your hand away from danger, even though the steam above the pot is only 212°F – lower than the oven’s temp. Why?

Steamy air carries a lot more energy than the same volume of dry air. In order to create steam in the first place, we had to pump a bunch of energy into water to make it boil. Once the boiling water turns into steam, it’s carrying that energy payload with it. When the steamy air lands on a cool piece of food, (or in this thought experiment, your hand) it condenses back into a water droplet and deposits all that energy right into the food’s surface. Humid air is also a far better conductor of heat than dry air, so with these two concepts together, cooking with steam can deliver heat to the outside of your food much faster than cooking in a dry oven.

However, since we are people of science, we are duty-bound to tell you the whole truth. Once the heat reaches the food’s surface, the rest of the cooking speed is governed by the heat transfer within the food. And sadly, that always moves at the same rate. This means that the speed benefit from steam cooking will be much more dramatic for thin foods like green beans, corn, and asparagus than for thick foods like a whole baked potato.

Keep it Juicy Juicy

Cooked Salmon Comparison

When you’re cooking in a traditional, dry oven, the air is… thirsty. Your gorgeous piece of king salmon is made mostly of water. And as it heats up, the dry air evaporates that water out of the fish, leaving it dry and chalky. If you could watch the cooking process in Evap-O-Vision, you’d see water, and the flavor molecules bound with it, escaping from the surface of the salmon like a comet shedding tiny ice crystals as it approaches the sun. It would be beautiful… if it weren’t so tragic.

However, cooking in a humid environment is a very different story. When air is at 100% relative humidity, it can’t absorb any more water. It’s full. Evaporation comes to a halt. That means that the water in your fish has no choice but to stay put , in your food, where it belongs.

So how do you achieve 100% relative humidity when cooking? Just set the Anova Precision Oven’s Steam Percentage to 100%, and be sure that your cooking temperature is under 100°C / 212°F. It’s that easy.

A Bread Baker’s Dream

You know the loaves: those impossibly voluminous, crusty, shiny, sourdoughs that rack up all the Instagram love. If you’ve attempted a bread like this at home and wound up disappointed, you’re not alone, and it’s not your fault.

Artisan bakers use specialized steam injection ovens to achieve those results. Steam is critical for this type of baking: it provides heat to the bread fast so the loaf gets maximum oven spring (the period of growth at the start of baking, before the crust has set). Steam also slows the crust from setting too early, and contributes to the shiny, crispy qualities of the outer crust that artisan bakers prize so highly.

Unfortunately, home bakers have had to resort to clever (often dangerous) hacks in pursuit of those same results. Raise your hand if you’ve ever thrown a fistful of ice cubes into a hot oven, had a spray bottle water fight with your oven walls, or played Indiana Jones trying to get your unbaked mound of dough into a scalding hot dutch oven in one, swift movement?

Say goodbye to all that nonsense.

The Anova Precision Oven has a powerful, dedicated steam boiler to produce continuous steam during the first phase of your bread baking. And, because the Oven uses a controllable vent, the steam that you produce will stay in the oven rather than escaping immediately, like it does in your traditional oven. Once your bread is fully oven-sprung, you can turn off steam generation, open the vent, and finish setting the crust and the crumb. Even better – you can automate all of the above using the Anova Oven app’s multi-stage recipe capabilities.

And Proofing, Too!

Take a look at our Sourdough Boule Recipe for inspiration!

Nutritional Benefits:

With so much focus on deliciousness, it’s easy to forget that steam cooking also offers nutritional benefits. Raw foods are loaded with vitamins and macronutrients. But, as with flavor molecules, some of those nutrients are water soluble. So, in order to keep the nutrients in your food, you also need to keep the water in your food.

That’s where the Oven comes in. The Anova Precision® Oven allows for exact temperature and humidity control to ensure that the best parts of your cooking aren’t wafted away. For instance, a pot of boiling water leaches nutrients from the food into the cooking water. So, unless you’re planning to drink that cooking water alongside your dinner, you’re missing out. By cooking in a fully saturated, steamy environment in the Oven, the water in your food has nowhere to go, so it stays put and keeps water-soluble nutrients in place with it.

Adding steam to your cooking stages in the Anova Precision Oven is easy.

Adjust the Steam % setting from 0-100% to add steam to any cooking stage. Or, if you’re cooking using the app, specify a Steam %. That’s it!

How Does Steam % Work, Behind the Scenes?

Specifying a steam percentage is easy. But let’s take a look behind the scenes at how the Oven generates and controls steam. The Anova Precision Oven has a dedicated, 1200W boiler, located behind the back wall of the oven. When active, the boiler produces steam that is then injected into the oven by the convection fan (for this reason, the Oven will ensure that the fan is running whenever Steam is enabled).

The Oven controls steam in two different ways, depending on the cooking conditions. We’ve simplified this down to a single Steam % for all cooking, but if you’re curious to know what’s really happening, here’s where we spill the [perfectly cooked] beans.

Cooking at 212°F / 100°C or lower

If you’re cooking at a temperature of 212°F / 100°C or lower, the Steam % you set is interpreted by the Oven as a Relative Humidity Percentage. So, if you set your cook to, say, 185°F / 85°C with 75% steam, the Oven will maintain an internal relative humidity of 75%.

Relative humidity is a measure of how much water is in the air, and is a complicated formula that accounts for the pressure and temperature of the air: hotter air is capable of holding much more water. But, you might already be familiar with relative humidity as the term that’s often used in weather forecasts. A high level of relative humidity feels muggy, and a low relative humidity feels dry. It’s the same phenomenon.

In this case, at 212°F / 100°C or below, the Anova Precision Oven measures and maintains the humidity level you have set, only activating the boiler when necessary to replenish humidity levels. Because the oven cavity is sealed and can maintain humidity well, the boiler doesn’t need to activate often, using less energy and less water than if steam were constantly escaping.

Note that, although the oven can add humidity by generating steam, it can’t dehumidify the air beyond the ambient humidity in your kitchen. So, if you set a very low Steam %, the oven may not be able to fully reach that target.

Above 212°F / 100°C

At temperatures above 212°F / 100°C, the Steam % you set specifies the amount of steam the oven will generate. In this mode, steam generation is constant and steady throughout the cooking process. The percentage you set, from zero to 100% determines how much power is used by the boiler. If you open the oven door, the boiler will kick on high for a few seconds to replenish lost steam before returning back to the normal rate of steam generation.

Why have two different modes?

Why did we go to the trouble of having the steam boiler operate in two different ways? It’s because relative humidity – and the math that goes into calculating it – falls apart when you’re hotter than the boiling point of water. It starts to become nonsense. As you get hotter than 212°F / 100°C, the maximum theoretically possible relative humidity plunges from 100% to very small numbers, really fast.

Rather than subject home cooks to this misleading and confusing state of affairs, we’ve collapsed the world into the two behaviors above. The result? Your prime rib will cook in a 100% relative humidity environment, with the boiler just sipping water and energy to maintain stasis. But, your dumplings and sourdough loaf are bathed in powerful, continuous steam to ensure predictable, consistent cooking.

When to add steam?

Cooking skinless meat, poultry, and fish to core doneness.

Cooking green vegetables to be vibrant in color and flavor. Ex: Asparagus, green beans, snap peas, broccoli, and brussels sprouts.

Cooking starchy vegetables to core doneness. Ex: potatoes, carrots, corn, beets, and squash.

Baking bread. In proofing stages, a high humidity environment prevents the outside of the dough from drying out. In the first stage of baking, steam injection prevents the crust from forming too early, helping the bread reach maximum volume. Note: turn steam off in the second stage of baking to fully set the crust and crumb.

Cooking egg dishes such as omelettes, and egg-set dishes such as custard, flan, creme brulee. Full or partial steam helps evenly and gently heat egg-based dishes, similar to using a bain marie in traditional cooking. Higher humidity in the Oven discourages water from evaporating away from the eggs, which would leave them brittle.

Cooking rice, grains and pasta. With steam at 100%, and some cooking liquid in contact with the food, can substitute for stovetop boiling.

This doesn’t mean that adding steam is always better. Sometimes you want to drive off water – it’s a necessary step to make anything crispy, for instance. And although steamed, vibrant vegetables are <chef’s kiss hand motion>, caramelized, roasted veggies are fantastic, too. With the Anova Precision Oven, you’ve got options. Here are some examples when steamless is the best strategy.

When Not to Add Steam

When crisping, browning, caramelizing, or “air frying”. Wet foods don’t brown. So, if you’re trying to sear or caramelize the outside of your food with high heat, water is your enemy. Keep the food and the oven as dry as possible for the best and most efficient results.

When cooking skin-on poultry. Steaming the skin as the poultry cooks will allow it to absorb moisture. This makes the skin harder to crisp in later stages and can result in a rubbery texture.

For most traditional baking. Most baking is about driving moisture out of your baked goods, so you want a dry environment ready to receive moisture from the food. Steam will inhibit browning, as well, so your cookies may end up more blonde and less toasted than with dry baking. Depending on the specific recipe, this may or may not be desirable. So, some exceptions certainly exist for this rule. But for the majority of traditional baking, steam does not add any special magic and may be detrimental.

For dehydrating. You’re trying to drive water out of your food, so steam will only slow that process down. You may want to do a steam blast before dehydrating to kill off surface bacteria, but during the actual drying process, you should disable steam (and even keep the oven door cracked so moisture can escape more easily)