Finally caved to my curiosity on extended time Sous Vide cooking after a heads-up from long time customer Joe L. during a recent beef delivery. He extolled the results of 48 cook time on a grass fed Hay Creek sirloin tip roast from my farm. I’d discounted the effect of these long (over 6 hour) cook times in the erroneous mindset of thinking the internal meat temperature would surely stabilize within that time and why cook longer? The reality is counter- intuitive and miraculous changes take place with extended time at relatively low temperatures: solving the ages-old problem of creating a moist but tender roast from a relatively lean cut of meat.
I did some quick searching and discovered 2 sources recommending between 17 hours @ 137 deg F and 46 hours @ 134 deg F. I wanted to test both “pot roast” and a “leftover” cold cut serving scenarios so applied an herb rub to the roast before bagging ( 1 gallon freezer ziplock) and inserting a half-dozen garlic cloves around the perimeter. Trick for eliminating excess air from bag (prevents floating) is to suck it out with a small-diameter tube like that used for aquarium aeration. Pinch the tube near the corner of the bag while sucking the air out and progressively sealing the zipper.
Some important Sous Vide considerations: Basic Sous Vide is well covered in this video. Curious to note that cooking in the 134 to 137 degree F range for hours violates the crude rule-of-thumb advocated by every Dept of Public Health: to minimize food residence time in the 40 deg F to 140 deg F temperature window for avoidance of food safety (microbiological) issues. Consider testing the calibration of your Sous Vide device if you hope to achieve comparable results to others . Despite their tenth degree F resolution, they can easily be inaccurate by 2 whole degree F. Test by immersing in boiling water on the stove top and recording the device’s temp reading. Boiling point temp must corrected for your local altitude. This is then the “real” temperature which you can then use to offset your device setpoint to compensate for any inaccuracy. The long cook time also pumps a lot of heat and moisture into your house so wrap your vessel with a towel and cover the water surface.
Removed entire bag to refrigerator after 46 hours @134 deg F and cooled 7 hours before draining fluid surrounding roast to a saucepan for finishing as a gravy. Seared exterior of roast in smoking hot frying pan with a couple T-spoons lard to minimize internal temperature increase. Cut and rewarmed slice from the seared exterior and served on boiled potatoes w/ gravy. Amazingly tender, moist and mild flavored. The fluid “juice” in the bag surrounding the cooked roast is loaded with proteins (foams readily on boiling) and quite intensely flavored so does not benefit from much reduction prior to adding thickening agent (flour or starch).
Cold cut slices best served on mild white bread like burger buns accompanied by Dijon mustard. So incredibly tender it isn’t crucial to slice thinly. So delicate in flavor that it gets lost with horseradish and sourdough rye.
Next try will be with roughly half the cook time to regain a little ‘”chew” texture.