Adding steam can speed up cooking, and it can keep proteins juicy and vegetables vibrant. Injecting steam at the beginning of baking is critical for producing big, airy, and 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.
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’d like over the full temperature range of the oven.
When setting the steam percentage below 212°F (100°C), the amount of steam is measured in terms of relative humidity. Relative humidity is a measure of how much water is in the air; hotter air is capable of holding much more water. 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 level of relative humidity feels dry.
At temperatures above 212°F (100°C), the steam percentage you set specifies the amount of steam the oven will generate.The percentage you set determines how much power is used by the boiler.
Imagine (but don’t try) putting your hand in a 300°F (150°C) dry oven. After a minute it’ll get uncomfortable, but otherwise, you’re fine. Now, 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 (100°C) — lower than the oven’s temperature.
This is because steamy air carries a lot more energy than the same volume of dry air. In order to create steam in the first place, a bunch of energy needs to be pumped 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, it condenses back into water droplets 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, once the heat reaches the food’s surface, the rest of the cooking speed is governed by the heat transfer within the food, which always moves at the same rate.
This means that the speed benefit from steam cooking will be much more dramatic for thin foods like steaks, chicken breasts, green beans, and asparagus than for thick foods like a prime rib roast.
When you’re cooking in a traditional, dry oven, the moisture in your food evaporates into the dry air. 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 food like a comet shedding tiny ice crystals as it approaches the sun.
However, cooking in a humid environment is a 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 food has no choice but to stay put.
To achieve 100% relative humidity when cooking, simply set the Anova Precision™ Oven’s steam percentage to 100% and be sure that your cooking temperature is under 212°F (100°C).
Artisan bakers use specialized steam injection ovens to achieve those signature crusty loaves of bread with perfect oven spring and an open, airy crumb. Steam is critical for this type of baking; it provides heat to the bread quickly so that 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 creation of a shiny, crispy crust.
Unfortunately, home bakers have historically had to resort to cumbersome hacks, like throwing fistfuls of ice cubes into a hot oven, in pursuit of those same results. The Anova Precision™ Oven helps you avoid these workarounds. It has a powerful, dedicated steam boiler to produce continuous steam during the first phase of bread baking.
If you’re cooking at a temperature of 212°F (100°C) or lower, the steam percentage you set is interpreted by the oven as a relative humidity percentage. If you set your cook to 185°F (85°C) with 75% steam, the oven will maintain an internal relative humidity of 75%.
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’s cavity is sealed and can maintain humidity well, the boiler doesn’t need to be activated often, which means it uses less energy and less water than if steam were constantly escaping. It also makes use of an evaporator plate on the bottom of the oven; this heats up and boils condensation for even greater steam efficiency.
Keep in mind 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 percentage, the oven may not be able to fully reach that target.
At temperatures above 212°F (100°C), the steam percentage indicates the amount of power used by the boiler to generate steam. In this mode, steam generation is constant and steady throughout the cooking process. 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.
We built the Precision Oven’s boiler to operate in two different ways because relative humidity falls apart and does not apply when the oven is hotter than the boiling point of water. As you get hotter than 212°F (100°C), the maximum possible relative humidity plunges from 100% to very small numbers.
Rather than have you worry about the math, we’ve made the steam controls the same, no matter the oven temperature you set. The result? Your sous vide steak will cook in an environment of 100% relative humidity, with the boiler just sipping water and energy to maintain stasis. But your basmati rice and whole artichokes are bathed in powerful, continuous steam to ensure predictable, consistent cooking.
When to Add Steam (and How Much)
Sous vide proteins.
100% relative humidity plus the food probe equals moist, tender, and perfectly cooked proteins every time.
Crisp-tender green vegetables.
Cooking green vegetables, such as asparagus, green beans, and broccoli, with 100% steam keeps them snappy, vibrant in color, and full of flavor.
Tender starchy vegetables.
Potatoes, carrots, corn, beets, winter squash, and similar vegetables, all benefit from at least some steam for even cooking. Start at 20% steam and experiment from there.
Eggs and egg dishes.
Full or partial steam helps evenly and gently heat egg-based dishes, similar to using a water bath in traditional cooking. For dishes where you may not want to see condensation on the top, try using 50% instead of 100% steam.
Cooking rice, grains, and pasta.
Setting the steam at 100% and keeping cooking liquid in contact with the food can substitute for stovetop steaming or boiling.
In addition to gentle steam cooking, adding 25 to 50% steam when cooking at higher oven temperatures can help vegetables like broccoli cook quickly and evenly while also allowing for charring.
A blast of 100% steam at the beginning of baking ensures a lofty oven spring, an open airy crumb, and a perfectly crisp crust.
Don't Add Steam
Air frying and broiling.
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.
Cooking skin-on poultry.
Steaming skin as 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.
When dehydrating, you’re trying to drive water out of the food, so steam will only work to slow that process down.