[Modernist Cuisine] Sous vide times appropriate for what starting temperature?

[Anonymous Modernist 6277]

The times posted for cooking should vary based on the starting temperature, what is the assumed temperature? Room temperature? Fridge temp? 36 deg? Is there a way to adjust for cooking from frozen?

[Scott Heimendinger]

Hi enochchoi,

In our Best Bets tables in Volume 3, the times given assume a starting temperature of refrigerator temperature, approximately 36F (2.2C). To calculate an adjustment in cooking time to factor in starting from frozen, take a look at the Suggested Times tables in 2.276 and 2.277. Based on the shape and thickness of your food, you can look up the additional time it will take to go from frozen to 36F.

[Anonymous Modernist 347]

I would strongly recommend the inexpensive Sous Vide Dash app for the iPhone and iPad for answering these kinds of questions. I bought an iPhone, just to get that app!

It does a detailed calculation based on heat transfer thermodynamics, similar to what Douglas Baldwin based his times and temperatures on. It allows you to specify the starting temperature of the food, the temperature of the water bath, the desired core temperature of the dish, and whether you want to simply raise the surface of the food that the desired level, or to pasteurize the surface, or pasteurize all the way to the core, and then tells you how long to cook it. It even plots the rate at which various pathogens are destroyed.

In addition, a recent revision allows you to calculate the cook-chill times, where the food is placed in an ice bath after cooking. Regrettably, it does not yet support one of my favorite cool-down techniques, where I use inexpensive vodka stored in the freezer at -10F, instead of ice at 32F. Obviously, that cools down the food, still in the SV bag, a whole lot faster, and the vodka is reusable, without having to fuss with lots of ice.

As I understand it, it isn't all that easy to calculate how much additional time is required to cook something from frozen, because of the latent heat that is required to transform ice into water, and the varying amounts of water that might be present in meat. You can use the tables in MC or in Douglas Baldwin's treatise as a starting point, but be aware that they are just approximations. If it is really important to you, throw the frozen food in the bath, and take it out from time to time until it feels just barely thawed, and then calculate the time assuming a 1C starting temperature.

[Anonymous Modernist 310]

Good idea for the vodka. A cheaper idea (There is no inexpensive vodka in Quebec!) is a strong brine (23.3%wt) it freeze at -21C. Unfortunately I don't have the freezer space for that!

[Anonymous Modernist 6927]

Robert Jueneman said:

I would strongly recommend the inexpensive Sous Vide Dash app for the iPhone and iPad for answering these kinds of questions. I bought an iPhone, just to get that app!

It does a detailed calculation based on heat transfer thermodynamics, similar to what Douglas Baldwin based his times and temperatures on. It allows you to specify the starting temperature of the food, the temperature of the water bath, the desired core temperature of the dish, and whether you want to simply raise the surface of the food that the desired level, or to pasteurize the surface, or pasteurize all the way to the core, and then tells you how long to cook it. It even plots the rate at which various pathogens are destroyed.

In addition, a recent revision allows you to calculate the cook-chill times, where the food is placed in an ice bath after cooking. Regrettably, it does not yet support one of my favorite cool-down techniques, where I use inexpensive vodka stored in the freezer at -10F, instead of ice at 32F. Obviously, that cools down the food, still in the SV bag, a whole lot faster, and the vodka is reusable, without having to fuss with lots of ice.

As I understand it, it isn't all that easy to calculate how much additional time is required to cook something from frozen, because of the latent heat that is required to transform ice into water, and the varying amounts of water that might be present in meat. You can use the tables in MC or in Douglas Baldwin's treatise as a starting point, but be aware that they are just approximations. If it is really important to you, throw the frozen food in the bath, and take it out from time to time until it feels just barely thawed, and then calculate the time assuming a 1C starting temperature.

[Anonymous Modernist 6927]

thanks for the above, just got the app and its great