Douglas Baldwin with two immersion circulators and a vacuum chamber sealer.
Since I got my immersion circulator in December I’ve discovered that there are two critical questions that always come up as I hold a piece of meat in my hands, ready to cook it sous vide: At what temperature should I cook this? And for how long? Despite the fact that two books were published on sous vide last fall it is the short yet comprehensive guide “A Practical Guide to Sous Vide Cooking” by Douglas Baldwin that I’ve found most useful to answer these questions. Those who have followed the eGullet thread on sous vide cooking will probably recognize Douglas Baldwin as one of the major contributors alongside Nathan Myhrvold. Out of curiosity and eager to learn more I therefore emailed Douglas and asked if he would be interested in doing an email interview.
ML: From your homepage I see that you are a PhD student in applied mathematics, how did you become interested in sous vide?
DB: I have always loved to cook. Before last January, though, I mainly cooked slow food. That is when I saw sous vide mentioned in one of Harold McGee’s NY Times articles. Wow. Cooking meat at its desired final core temperature is so obvious! As a mathematician, I kicked myself for never asking “if overcooked meat is bad, what temperature should the meat be cooked at?” A question which many mathematician would instantly answer, “just above the temperature you want it to end up at.”
A quick search of the web led me to the massive eGullet thread on sous vide cooking. While the thread contains a treasure-trove of practical information — especially Nathan Myhrvold’s posts — it left me with a lot of unanswered questions. Being an academic, I turned to the scientific literature for answers; as expected, I found many answers and many more questions.
ML: Your excellent sous vide resource, “A Practical Guide to Sous Vide Cooking” has a wealth of information. What drove you to write this article? And have you ever considered publishing it in a peer reviewed journal?
DB: Thank you. I’m very glad to hear you find my guide to be useful.
As a scientist, I am driven by two things: an insatiable curiosity to learn everything I can about a topic and the desire to freely share what I have learned with the world (so others can extend and build on what I have done). After spending hundreds of hours researching sous vide cooking and discovering how much of the information online was incorrect (and potentially dangerous), I felt compelled to write up what I had learned and post it as soon as possible. I am still actively working on my guide, and hope to complete another major revision in February.
I have not submitted my guide to a peer reviewed journal because its intended audience is chefs and foodies. Though I did ask a number of food scientists to review my guide for technical accuracy, and I was recently asked to referee a paper for the Journal of Food Science.
ML: From your viewpoint, what is the biggest advantage of sous vide over conventional cooking?
DB: Control. Precise temperature control gives incredible choice over the doneness and texture of meat, poultry and fish. Tough cuts can be made tender. Tender cuts are the same perfect doneness from edge-to-edge. Fish and light meat are moist and flavorful. Pork and poultry no longer needs to be brined to be juicy (because they can be made safe without being cooked well-done).
ML: Do you think sous vide cooking will ever become so common that the equipment will be available in regular kitchen stores? And if yes – when will that be?
DB: I don’t think sous vide cooking will ever be so common that immersion circulators will be sold next to microwave ovens. But I fully expect them to be as common as smokers in 5–10 years. Like smoking, sous vide cooking requires a little knowledge and planning — an easy request of the average Khymos reader, but a lot to ask of most consumers. This is unfortunate, because I find sous vide cooking to be convenient, energy efficient, and versatile.
ML: What kind of equipment are you using yourself at home for sous vide? And how often do you typically cook sous vide?
DB: I use a Minipack-torre MVS31 chamber vacuum sealer and a PolyScience 7306C immersion circulator for most of my sous vide cooking. I usually attach the immersion circulator to a full-size countertop food warmer with a lexan lid I made — the lid limits evaporative cooling and the food warmer speeds the (initial) heating of the water and limits heat loss from the bottom and sides of the water bath. I also have a couple Iwatani butane blowtorches, a used PolyScience immersion circulator, a couple PID controllers from Auber Instruments, a Ranco ETC temperature controller, a FoodSaver vacuum sealer, and a bunch of thermocouples and meters from ThermoWorks.
I eat food cooked sous vide almost everyday. As a single guy, I batch cook most my meat in single servings pouches, rapidly chill and then freeze them until needed. While this `cook-freeze’ sous vide is very convenient, the freezing and reheating of the meat does causes small, but noticeable, degradation in taste and texture.
ML: Have you compared DIY bagging with zip-lock bags, food saver bags and vacuum chamber packs? I know that liquids are challenging with the food saver, but does the bagging method affect flavor (or even texture)? Does the small amount of oxygen in the DIY version have any effect?
DB: For meat, different bagging methods have little or no effect on flavor and texture. The primary purpose of bagging is to allow the efficient transfer of heat from the water (or steam) to the food (while still keeping the food and water separated). Sealing the food in a bag has the added benefit of preventing evaporative losses of flavor volatiles and moisture. Even when using a chamber vacuum sealer, the majority of bags have high levels of residual oxygen. The main difference between using a zip-lock bag and a chamber vacuum sealer is the extent to which the bags balloon when heated; (when heated over about 65C/150F) both bags will start to balloon because of the vapor pressure of the liquid in the bag, but the zip-lock bag will balloon more because the residual air in the bag will also expand. It is important that the food is kept from floating to the surface of the water to prevent uneven heating.
While meat can easily be cooked in a zip-lock or food saver bag, fruit and vegetable compression requires a chamber vacuum sealer. Moreover, zip-lock and food saver bagged vegetables balloon excessively in the 85C/185F water bath they are (typically) cooked in because it very difficult to remove all the air in the bag.
Liquid in the bag is indeed problematic when using a food saver, but is easily solved by freezing the liquids before bagging. (Although, I might add that freezing often traps air bubbles in the liquid which cause the bag to balloon more than it would have if a chamber vacuum sealer was used.)
ML: What are your favorites cuts of meat for sous vide?
DB: With the faltering global economy in mind, I love showing off sous vide cooking’s ability to transform inexpensive cuts of meat into something amazing. Consider the humble chuck roast, a flavorful cut of beef which is usually relegated to stews and hamburger because of its abundant connective tissue. Vacuum sealing, cooking for 24 hours at 55C/131F, and searing to a beautiful mahogany color transforms this humble cut into something akin to prime-rib! Pork shoulder vacuum sealed with lard and cooked for 24 hours at 68C/155C, torn into bite-sized hunks and fried in a little oil is always a hit at my dinner parties. Even the the lowly chicken breast can be made into something moist and flavorful by pasteurized in a 60C/140F water bath (see my guide for pasteurization times).
ML: Is there any meat that you would prefer not to cook sous vide?
DB: I don’t like some types of fish cooked sous vide. When cooked too slowly, the enzymes in the fish remain active and cause the flesh to become mushy. [This can be mitigated by using a water bath temperature 5–10C/10–20F higher than the desired final core temperature and using a needle temperature probe inserted through closed-cell foam tape to determine when the fish is done heating.] Also, fish which is not extremely fresh will taste too fishy because the flavor volatiles remain sealed in the bag with the fish —this is a particularly irksome problem for me in land-locked Colorado.
ML: Some critics claim that with sous vide, even though you brown the surface, you loose some flavor since temperature is kept so low (I believe this applies especially for pork). Do you share this experience?
DB: It is a very reasonable concern, but can be mitigated by quickly searing the meat before vacuum sealing and cooking. While the initial Maillard reaction occurs noticeably above 150–180C/300–350F, many of the subsequent reactions can occur at the low temperatures used in sous vide cooking. Personally, I feel searing after cooking is sufficient and almost never take the time to pre-sear my meat.
ML: From your experience, what is most difficult to achieve when cooking sous vide?
DB: A great sear without overcooking the meat. While a blowtorch works wonders on beef and (most) pork, it tends to burn poultry. A pan with a little oil over medium heat (so the oil is between 150–180C/300–350F) works fairly well for poultry, but may overcook the meat before the surface is golden brown.
ML: With Keller’s recent book “Under pressure” and your guide (and an extremely long thread at eGullet) being available now: Which areas would you say need further exploration?
DB: Sous vide cooking is still relatively young and there are hundreds of interesting questions yet to be answered! Some of the questions I’m currently interested in are: How long does it take all the soluble collagen to unfold into gelatin at 55–65C/130F–150F? What is the role of enzymes when cooking at low temperatures for long times? Is it better to thaw the meat or cook it from frozen? If cooking from frozen, how long does it take to heat a piece of meat (such as foie gras) stored at -80C/-110F? Which foods can be frozen or refrigerated after cooking (and for how long?) without significantly degrading taste or texture? How and why should fruits and vegetables be cooked sous vide? Why does fish retain so many more of their essential fatty acids when cooked sous vide (compared with conventional cooking methods)? . . .
In addition to the many unanswered questions, there are also many topics which are understood but have yet to be discussed in sufficient detail. For example, many people’s intuition about clamp and chamber vacuum sealers is wrong. The importance of food shape in predicting heating times has not been discussed — spherical and cylindrical foods heat much faster than slab shaped food. The relatively fast onset of warmed-over-flavor after the food is removed from its vacuum pouch is absent. And even how large and powerful the water bath needs to be for a given quantity of food has not been discussed.
Hopefully I, Nathan Myhrvold, or someone else will have the time and resources to answer all these interesting questions.
ML: Thank you very much!