Cooking is a balance of temperature and time. Lowering the cooking temperature and extending the cooking time can have profound effects on meat, vegetables and even desserts according to Andrew Schloss, author of Cooking Slow: Recipes for Slowing Down and Cooking More.
Lynne Rossetto Kasper: What is the difference between what happens when you cook slowly versus the way we normally cook?
Andrew Schloss: All of cooking is a balance between temperature and time. As you start to lower temperatures and naturally extend time -- because it just takes longer to cook -- you affect the way heat works with foods differently. The most profound effect is on proteins.
Meats will become done at a certain temperature. A rare roast beef, for instance, is 130 degrees Fahrenheit. If I'm roasting that beef in a 400-degree oven, the outside of the beef is getting well done, it's getting up to 400 degrees Fahrenheit. In order to get that center to be perfectly rare, if I have my oven set at 130 degrees Fahrenheit, the entire beef is rare, I get the juiciness all the way through, and the texture of the protein, the way it sets up, is just very, very soft. You get a huge difference when you slow down that process and lower the temperatures.
LRK: It sounds like it's affecting the cellular structure of the meat.
LRK: When those cells are heated very quickly or taken to a very high temperature, there's actually shrinkage that releases moisture?
AS: Yes, proteins will shrink up. They get tighter as they get hotter. You see this most when you fry an egg or scramble an egg. If you put the egg in the pan, you can see that the protein at first is clear and liquidy. Then as the heat affects it, it will start to tighten up and become white and opaque. Eventually, if your pan is really hot when you put a fried egg in there, it almost turns to like a plastic at the edge. That's very over-coagulated protein. If you never let that temperature get that high, the protein stays soft, succulent and tender the entire time.
Schloss' recipe: Salmon with Spiced Red Lentils and Bacon (Photo: Alan Benson)
LRK: The danger area in temperatures where harmful bacteria could grow is between 40 and 140 degrees Fahrenheit. You have that meat sitting there very slowly getting to even below that temperature. What about the safety issues, especially with proteins, of cooking very slowly?
AS: Whenever you're dealing with a solid protein, with a solid piece of meat or something like that, all of those bacteria are on the surface of the roast. There's not a significant amount of bacteria interior in the muscle. That's why in ground meat it's much more of a problem, because in ground meat the outside becomes the inside. But as long as the meat is a solid piece, that bacteria is on the outside.
Whenever you're slow-cooking roasts, you want to do some measure to alleviate the amount of bacteria on the surface of the meat. That is either done through browning, just in a pan before you put it in the oven, or you can start it in a very high oven. If I'm doing that, I'll start at 425 degrees Fahrenheit and let it go for 30 minutes or so, so the surface becomes at least 200-300 degrees Fahrenheit before I lower the temperature.
Sometimes with poultry where I don't want to brown it a lot first, I will salt the meat. I do this with roasts too -- put a good amount of salt on the surface of the meat and let it sit in the refrigerator overnight, which will subside the amount of bacteria on the surface. Then you wipe that salt off and it seasons the meat as well.
LRK: What happens with vegetables?
AS: With vegetables it is not as profound an effect. It's interesting because one of the things I thought would be great in this book was roasting vegetables. The roasted vegetables I like better cooked at a high temperature, so I ended up not doing a lot of roasted vegetables.
An example of a vegetable that I did that was amazing was roasted carrots on coffee beans, which was a technique that I picked up from the restaurant Coi in San Francisco. What happens there is you lay carrots on coffee beans. At a very low temperature the oils in the coffee beans emerge -- they start to weep out of the coffee beans and infuse into the carrots. It's different than a carrot rubbed with coffee or poached in liquid coffee. It almost is like it's inundated with the spirit of coffee. It's an amazing thing that happens. I also did that with beets and it was wonderful.
LRK: You do something in the book that's really unusual -- you slow-bake desserts. How does that work?
AS: This was something I discovered because I'm lazy. I used to work in restaurants when I was younger. I always wanted to have something cooking while I was sleeping. I had a lot of cheesecakes on my menu at that point. Cheesecakes are just custards where instead of having milk as your liquid, you have cream cheese as your liquid or ricotta cheese or whatever your dairy is in the custard. All the recipes I had ever seen baked the cheesecake in a water bath. The purpose of baking in a water bath is it keeps the median temperature around the food at 212 degrees Fahrenheit maximum.
I was thinking, "Why can't I just set my oven at 200 degrees Fahrenheit, and then I don't need a water bath?" I did that and it was amazing because the cheesecake never overcooked. You know how the edges of a custard will get grainy because they'll get hotter than the center will?
LRK: Yes, and it weeps.
AS: This didn't happen. It was perfect from the middle to the edges. So I started doing custard-like desserts -- puddings, cheesecakes, cream pies, fruitcakes -- things that don’t require a lot of gluten production to raise the cake. Lowering those temperatures worked amazingly.
The one thing when you do that, when you're lowering your oven temperature down to 200 or even 180 degrees Fahrenheit to set the batter, the baking time starts to extend. These cheesecakes that I was doing, it turned out that they took about 8 hours to get done, which was about the amount of time that I slept. So I realized that I could just at the end of the night stick the cheesecakes in the oven, go home, go to sleep, come back in the morning and I would have desserts for the restaurant.