How green is DIY sous vide cooking?
Last Christmas, I was given a copy of The Food Lab book by J. Kenji Lopez-Alt, an incredibly interesting and comprehensive dive into the world of food science, designed specifically for us home cooks who may not have all the latest gadgets and gizmos, who aren't necessarily into "molecular gastronomy," and who really just want to master the art of perfect scrambled eggs and such.
I was not disappointed.
Among the techniques showcased in the book was a cheap hack for cooking meat "sous vide"—a method in which food items are sealed in a vacuum and then gently brought up to temperature in a water bath. The culinary benefits are many—it's easy, it achieves a very precise and even temperature throughout the food being cooked, and it makes the timing of your meal more flexible too. Once your food is cooked, it can sit at the correct temperature until you are ready to finish it.
The trouble so far has been that professional sous vide equipment has been prohibitively expensive for most home cooks (or it involved some DIY sabotage of a rice cooker). While that has been changing of late, with the advent of cheaper immersion heaters like the Anova Precision Cooker, J. Kenji Lopez-Alt's method is even cheaper: You just put some water at the correct temperature in a beer cooler, and then dump your sealed food in that water. Within 45 minutes you have a perfectly cooked steak, chop, brat or whatever. (Because of the higher temperatures needed, the method is not ideal for sous vide vegetables—so that's one downside on the green front already...) Here's a basic instructional below:
But how green is this method? On the one hand, it turns out that sous vide cooking—even the kind that uses professional equipment and takes several days—is still relatively energy efficient compared to traditional cooking techniques. There are plenty of forums and blogs that have experimented with what I'll call "active sous vide," showing pretty minimal energy consumption that compares well to a stove or oven. But when you remove the embodied energy cost of a dedicated sous vide cooker, and you go with a cook time of 45 minutes to a few hours—as you do with the beer cooler method—there surely can be no comparison. Because you're not bringing anything up to boiling point, and you can start with the hot water straight from the tap (it never comes into contact with the food), the active heating time can be measured in a few minutes.
But what about the plastic? That's a trickier question. On the one hand, in the same way that the single-use coffee cups and pods have led to a mountain of waste, I think it would be fair to worry about an increased use of disposable plastic in the kitchen. But then, many of us reuse our Ziploc bags many times over. While there may be concerns around reusing plastic bags that have contained raw meat, one option is simply to use bags for other purposes first—assuming you're not a zero waste household—and then eventually turn them over to a last use as a sous vide container. Others claim that you can was bags in the dishwasher and/or soak them in sanitizer—but I'm going to stop short of advocating for that until I can afford a good lawyer. (And I won't share if I have done this myself...)
There are also ways to practice sous vide using glass jars or reusable silicone pouches, although the lower flexibility of these materials may prove cumbersome with an irregular T-bone steak, for example. Apparently Lekue reusable bags are quite popular for this purpose...
Of course, any discussion of food and plastic isn't going to go fat these days without concerns about leaching chemicals. Here, the jury appears to be somewhat mixed—with a general feeling that as long as you avoid plastics with BPA, phtalates and other plasticizers you're probably OK, especially given the low temperatures involved. I confess that I tend to be a little blasé about such exposures anyway—given the fact that unless we shop exclusively at the farmers' market and stick with 100% local, seasonal and unfrozen, much of our food will have been in contact with plastic at one time or another.
I've even been known to cook foods sous vide in the vacuum packed plastic they came in from the store., but I'm sure there'll be someone out there ready to tell me I am mad. Thoughts, anyone?