Steam Baking In A Convection Oven

[ For more information about LTB terminology, see Low Temperature Baking: A Journey of 3 Paths ].

Not long after I began using my Cuisinart counter-top convection oven for slow baking and dehydration, I thought about the possibility of baking with moist heat. Steaming pastries in a boiling water steamer is a form of baking on VaporBaker, although technically, it is not considered baking. The air inside a standard stove-top steamer, for example, never exceeds 212°F/100°C with 100% humidity. However, a new type of home appliance, the steam oven, claims to bake either by spraying low-pressure superheated steam over food (heated to 572°F/300°C) or by alternating steam heat with dry heat (a.k.a. a combi-oven, which, in some models, even has settings for the percentage of humidity).



Steam baking fills in the spectrum between dry heat baking and basic steam cooking. In the context of low temperature baking, VaporBaker defines "steam baking" as baking in a controlled humidity environment between 212°F/100°C and 300°F/149°C (250°F/121°C being my preferred temperature), where the pan does not touch water as it would in a bain marie. For that purpose, I've fitted my Cuisinart oven with a water tray, configurable to release low or high moisture. It's not quite the same thing as a commercial steam oven or a conventional boiling water steamer, and the cooking times differ for all of them, but steam baking is a hybrid technology and does produce interesting results. For the health conscious, the moist heat and low temperatures (250°F/121°C or less) discourage the formation of acrylamides. Moist heat also discourages browning.

The "water tray" is actually the 2-piece broiling pan included with the Cuisinart oven. The pan covers the entire floor of the oven, and when filled with boiling water, can evenly humidify the air inside. I use it with and without the top grill, depending on the humidity desired. The grill has a perforated, wavy surface that restricts the flow of steam, while allowing hot air to circulate all around the baking pan. Without the grill, I put a trivet in the water as a support for baking pans. If a baking pan were to sit in the water, the bottom would heat significantly faster and the setup would be more like a bain marie.

The low profile of the broiler - barely 1 inch tall - leaves plenty of space for pans, even my high-collar springforms. For regular steam baking, I fill it only about half way with boiling water, and refill it about every 20 to 30 minutes during baking. For wet-dry steam baking, I fill it with about 1/8 inch or less water, so that the tray dries out after about 30 minutes. In wet-dry steam baking, steam quickly heats the food and conditions it (keeps it moist), and then dry heat crisps and finishes the baking. The water tray is a nice LTB re-purposing of the broiler, which would otherwise see the light of day only as a dehydration tray. In order to obtain an effective 250°F/121°C interior (and counter the cooling effect of steam), I preset the oven higher and always verify the temperature with a thermometer.


Preparing the Water Tray:



1. Place the bottom part of the broiler on the oven's rack and fill to the desired level (half full for regular steam baking and 1/8 inch for wet-dry steam baking) with boiling water.




2. If desired, install the perforated top section or vented grill to limit the amount of steam. If the water tray is fully exposed, place a trivet (such as a round cookie cutter) in the center to raise the pan just above the water line. A trivet allows the air to circulate evenly around and under the pan.


3. Slide everything inside, close the door and pre-heat to the target temperature. With the vented grill on, I have to set my oven higher to 275°F/135C to reach an effective 250°F/121°C interior. With the water tray fully exposed, I have to set the oven to 300°F/149°C for the same 250°F/121°C interior.




4. When the preheat is ready, put in baking pan, either on the trivet or on the vented grill.



The above pictures show sliced carrots baked 3 ways at 250°F/121°C: dry heat, semi-moist heat (with the tray grill on) and moist heat (without the grill for maximum humidity). The baking time for all 3 batches was 30 minutes. The dry heat carrots came out shriveled and tough. The low-humidity moist heat carrots were softer, still very crisp and plump, lightly dessicated and curled on the top layer. The high-humidity baked carrots were tender enough to cut with a fork with a little bit of dryness on the top layer. A boiling water steamer would take about 10 to 15 minutes for the same degree of doneness without any dryness.




In these pictures, two cakes were baked in a moist heat oven at 250°F/121°C, the top cake over a grill-covered water tray (low moisture) and the bottom one over an open water tray (high moisture). The bottom cake rose slightly higher with more surface cracks, because the high humidity transferred heat faster. Neither cake really browned, but the less dense top cake was prone to a bit of singe. The choice of high or low humidity and fast or show heat transfer lies with the type of pastry being baked and the desired textures and flavors. Comparing e cake made in a boiling water steamer, the surface would have been a little spongier and the crumb a bit firmer, and the baking time possibly reduced by half.