Sous-vide and low temperature cooking are the first two molecular cooking techniques we experimented with. While other techniques enable previously impossible textures and flavor combinations, cooking food under vacuum and/or in a circulating water bath at its simplest offer optimization and precision control over traditional culinary processes of marinating and cooking. Marinade is pulled into some interstitial airspaces when the vacuum is first established, replacing the evacuated air. When the vacuum is broken the incoming air push the marinade further into the food. With the ingredients in an oxygen free environment, low-temperature cooking is possible whereas under normal conditions, food cooked for so long a time as required by the low temperature end up stale, oxidized, and dry. On the other hand, food cooked low temperature are flavorful, moist, tender, and always at the desired level of doneness. Much more information about sous vide and low temperature cooking can be found at CookingIssues.com in these posts: 1, 2, and 3.
The equipment to apply these techniques need not cost thousands of dollars. Here is how we put together our set up for around $300:
The heart of our sous-vide machinery is a bicycle pump whose valves are replaced so that air can only flow in the opposite direction than is usual. Instructions for such a useful thing are found at Instructables.com. Replacement check valves are mail-ordered stainless steel aquarium valves, originally designed to prevent water from flooding air pumps. The plastic valves available at the one pet supplies chain stores or the other pet supplies chain stores are both crummy but they will do in a pinch, for a day or two.
Next to the pump is a trap flask, gotten from a science surplus store – it’s airtight except for two outlets. The hose through the rubber topper leads to the vacuum pump. The hose attached to the side nipple goes to food containers. Air is pulled from the food containers, up through the topper hose, into the vacuum pump. Any marinade also sucked out of the containers remain in the flask. The flask isn’t strictly necessary, but rancid marinade mixed with vacuum grease smell terrible, and are exhausted right at the pumper through a hole on top of the pump.
We use two types of containers for food to be put under vacuum. The Foodsavers Freshsaver bags are used only for marinating. The orange thing is a bottle cap which adapts the vacuum hose to the check valve on the bags (square tab inside green circle). The mason jars are used when we need to marinate or cook things under vacuum. The white thing is a Foodsaver adapter for mason jars. There are plastic cooking bags available, but cooking in glass just seems safer.
Having put food under vacuum, here is how we cook them at precise temperatures:
The winged thing with the red nozzle is a regular aquarium pump. The squished golf club next to it is an 1000W immersion heater. It’s originally intended for folks out in the boonies who need to thaw frozen troughs of water for their cattle, or else boil up barrels of water for their own household. Both the immersion heater and the pump go into the largest tub of water that we need for a particular job. The heater does what it does and the pump circulates water so that the temperature is uniform throughout. The immersion heater is plugged into the box on the right, a Sous Vide Magic PID controller. It calculates how long and how hot to run the heater to achieve a steady state temperature within 0.1 degree of the set target. It actually accounts for around 90% of the cost of the whole set up, but it works great. In fact, our set up is the equal of any circulating water bath costing 3-10 times as much. And those can’t be converted to run as a very precise hot tub heater.
Having put all this together and playing around, we are of course finding many other uses for the vacuum and water bath beyond optimized marinating and cooking. Vacuum infusion of flavor and the pressing action from the atmosphere on the melons in vacuum bags is essential for our Orchard Sushi. The stability and convenience of vacuum packed and cooked food make our multi-course dinners possible, even if a dinner occurred during an intense workweek or 4 hours away from our home kitchen and equipment. Finally, working the pump is a fine exercise for our guests to work off their previous courses to make room for the following ones.