The ultimate bible for sous vide cooking is an article by Douglas Baldwin called "A Practical Guide to Sous Vide Cooking"
http://www.douglasbaldwin.com/sous-vide.html The bulk of what follows is from this article, and bit and pieces I've gathered after reading through quite a few sous-vide related web sites.
Basically, sous vide is the act of heating up your ingredients to a certain temperature in a sealed bag, in a temperature-controlled water bath. This technique is a function of temperature and time. How long to cook something in sous vide is dependent on the temperature you apply. The rough formula (based on my understanding, no other website explains the breakdown, at least the ones I've visited thus far) is as follows:
Total time = pre-heat time + come up time (CUT) + pasteurisation time + hold time
Pre-heat time is the time required for the water bath to be heated to the cooking temperature. This is dependent on the volume of water, the container, the power of the heater, and so on. This time is not usually considered when cooking sous vide, but still got to keep in mind. One way to accelerate this step is to use water you heated from a kettle. For all extents and porpoises (good joke), pre-heat time is zero (in the context of cooking time). This because you don't put your ingredients into the water bath until AFTER the water bath has reached the cooking temperature.
The next segment of time is called Come Up Time (or just "heating time" in table 2.2 and 2.3 of Baldwin's article). This is the time that is requried for the centre of your ingredient to reach within 1degC of the water bath's temperature, or really, uniformly have that temperature across the entire thickness. This time is dependent on the thickness of your ingredients, and the temperature of the water bath. So for a sous vide item to be considered "cooked", the item needs to be in the water for this amount of time. "Cooked" in the case of meats, just means that the protein is heat treated to whatever temperature you wanted it to be, as this CUT affects meat doneness. Higher temp, more done. General rule of thumb is that 60degC is medium well for beef.
After CUT, the next segment of time is called pasteurisation time. This is the amount of time needed to reduce the spoilage bacteria across the entire piece of meat down to almost zero (because zero doesn't exist,
duh). For beef, this is Table 5.1 in Baldwin's article. The general guide is that for superbly healthly individuals, skipping pasteurisation time for certain meats is fine as the risks are no different from conventional cooking. You need to apply pasteurisation time if you're feeding the meal to immuno-compromised people, like young children, old people, and sick people. Some meats are no compromise even for healthy people, like chicken. You also need to apply pasteurisation time if you intend to freeze the item after sous vide. Botulism is no joke, especially if cooked in a vacuum bag.
Pasteurisation time is not applicable when cooking below a certain temperature, as those temperatures typically promote bacterial growth instead of inhibiting it. When cooking below certain temperatures, the advice is to serve it as soon as the meat has reach the desired temperature (CUT), and only to healthy people. The usual risks of eating undercooked food applies.
Beyond pasteurisation time, is what is commonly called hold time. This is the amount of time you hold the food in the water bath before serving. This hold time is usually added after pasteurisation time to enable enzymes to further break down the meat to tenderise tough cuts of meat, like brisket, skirt or rump. Although it is commonly said that food cooked sous vide can be left in the water bath for prolonged period of time, there is actually a maximum duration you can leave certain food in the water bath before the enzymes overtenderize the meat to the point of being mushy or even liquidy. Examples of such ingredients are fish, seafood and chicken. Fish are generally not held for pasteurisation time for this reason, as prolonged pasteurisation can lead to mushy fish.
The upper limit of hold times can be referenced at this website:
http://www.molecularrecipes.com/sous-vide-class/sous-vide-cooking-time-temperature/
On the topic of tenderizing, there is a technique in sous vide called warm ageing. It simulates the enzyme activity that typically comes from normal ageing techniques. It involves initially holding the meat at 39degC for an hour, then 49degC for another hour, then only commence normal heating for CUT. Required reading:
https://stefangourmet.com/2012/02/27/sous-vide-to-the-next-level-tenderizing-beef-by-warm-ageing/
https://forums.egullet.org/topic/148167-modernist-cuisine-sous-vide-tenderizing-stage-and-enzymatic-activity/
eGullet also has an extensive thread populated with bookmark links to various discussions on sous vide.
This website gives a lot of visualisations for the effect of temperature on the result of sous vide (including the egg chart I replied on to make my first sous vide egg!):
http://www.cookingissues.com/index.html%3Fp=3911.html
This paper explains that is a tough cut and what is a tender cut of meat:
http://meat.tamu.edu/ansc-307-honors/meat-tenderness/
This website has some helpful visualisation of where the tough and tender cuts of meat are:
https://www.fix.com/blog/identifying-steak-cuts/
Also check out the Sous Vide Everything YouTube Channel for lots of sous vide eating:
https://www.youtube.com/channel/UCpFuaxD-0PKLolFR3gWhrMw/videos
Next post I'll discuss some possible sources of good clean meat.
Note: I've only had one meal of experience with sous vide at this point. Please do your own reading instead of depending on my understanding of the technique. Food safety is extremely important. Make sure you understand it before proceeding. I highly recommending reading up on current regulations on sous vide cooking of different countries to internalise some best practices. The one I've read is from the British Columbia Centre of Disease Control:
http://www.bccdc.ca/resource-gallery/Documents/Guidelines%20and%20Forms/Guidelines%20and%20Manuals/EH/FPS/Food/SVGuidelines_FinalforWeb.pdf This guide is where I gathered the term CUT from :) I like how it parallelises the role of a chef and a food safety inspector, as they basically follow the same guidelines, but for different purposes.
That's it for now. I'll populate this post with reading materials as I discover them from time to time.
