Hi everyone, I need advice because I cooked a pork loin roast (marinated for 24 hours) at 59C for 5 hours and it came out very tough and dry. What did I do wrong? These days I’m trying different cuts of meat but I’m not able to reach the desired tenderness, I’m here for suggestions. Thank you in advance!.
Hi ya @AliBold
J. Kenji Lopez-Alt says Medium: 140°F / 60°C for 1 to 4 hours - Firm but still tender, moderately juicy.
He did not marinate. A marinade might be hypotonic or hypertonic depending on the osmality. What was the concentration of salts / sugars in your marinade?
The brine surrounding the cells has a higher concentration of salt than the fluid within the cells, but the cell fluid has a higher concentration of other solutes. This leads salt ions to diffuse into the cell, while the solutes in the cells cannot diffuse through the cell membranes into the brine. The increased salinity of the cell fluid causes the cell to absorb water from the brine via osmosis.
Twenty-ish years ago when I learned brining I had a long discussion of osmality with my soon to be doctor (PharmD) daughter. It was then that I realized that she is / was an accomplished adult. I was very pleased and still am. She is threatening to leave ‘medicine’ for all of the bureaucratic BS interfering with her patient care.
Edited to add: From the Mathematical Chef Dr. Douglas Baldwin ‘Practical Guide to Sous Vide’
Marinating, Tenderizing and Brining
Since todays meat is younger and leaner than the meat of the past, many cooks marinate, tenderize or brine the meat before vacuum packaging.<
Most marinades are acidic and contain either vinegar, wine, fruit juice, buttermilk or yogurt. Of these ingredients, only wine presents any significant problems when cooking sous vide. If the alcohol is not cooked off before marinating, some of it will change phase from liquid to vapor while in the bag and cause the meat to cook unevenly. Simply cooking off the alcohol before marinating easily solves this problem.<
Mechanical tenderizing with a Jaccard has become quite common. A Jaccard is a set of thin blades that poke through the meat and cut some of the internal fibers. The Jaccard does not typically leave any obvious marks on the meat and is often used in steak houses. By cutting many of the internal fibers that would typically contract with heat and squeeze out the juices, it can slightly reduce the amount of moisture lost during cooking. For instance, when cooking a chuck steak for 24 hours at 131°F (55°C) the Jaccarded steak lost 18.8% of its weight compared to 19.9% for the non-Jaccarded steak. In general, more liquid weight is lost the longer a piece of meat is cooked at a given temperature– however, this additional weight loss is balanced by the increased tenderness from collagen dissolving into gelatin.<
Brining has become increasingly popular in modern cooking, especially when cooking pork and poultry. Typically the meat is placed in a 3 to 10% (30 to 100 grams per liter) salt solution for a couple of hours, then rinsed and cooked as usual. Brining has two effects: it dissolves some of the support structure of the muscle fibers so they cannot coagulate into dense aggregates and it allows the meat to absorb between 10–25% of its weight in water (which may include aromatics from herbs and spices) (Graiver et al., 2006; McGee, 2004). While the meat will still lose around 20% of its weight when cooked, the net effect will be a loss of only about 0–12% of its original weight.<
Ali, did you simply finish it off in the oven too long (no info provided so guessing) sous vide will retain moisture, so what was the next step?, details…
What was the marination material / sauce?
We tend to let meat do the talking in the most basic form when learning from new, as it displays original taste & texture as a base board to work from, too much marinading can ruin a meats fibres to be frank.
Don’t go for large slabs of meat, when feeding your family with this new tool “too much pressure” when starting out, cook a few at different smaller pieces to get a good feel as a cook prior to dazzling anyone else.
Cheaper & smaller cuts just like learning to walk wasn’t in giants strides.
(& do try the lamb) 
Today, after my bone in leg of lamb (55c 36+ hours) I upped the temp to 58.5c & threw in 2 halved pork loin (my anova wasn’t in the mood to connect so it was .3 of a degree c off the recipe, …
(which I did with brown sugar, liquid smoke & maple, no salt) …stupidly did not check the recipe (brain injury) so pumped the oven up to 250c when it came out of the water, remembered (checked after 7-8 mins) & finished off in a pan of oil (no butter, easter closed shops, so just what was in the pan) …it didn’t hit more than 65c momentarily in the centre (probed) & a few minutes on the induction hob finished it a treat giving tangible crispy outer & brown outer slight crunch prior to the beautifully rendered fat & meat which we had with a ceaser salad, thin sliced the meat with a hollow cheese knife (a favourite) as the meal was very ad hoc late eating.
Nothing dry, just 3 notably contrasting textures, could have improved on the maple flavour from the juices but that wouldn’t go with salad, …ah well, plenty left.