We saw how slow cooking beef affected the mass loss and temperature over time, but how does this relate to qualitative noms?

First off, apologies for the delay between the quantitative and qualitative assessments on this experiment. Researching the collagen to gelatin conversion took a back seat to the edification of summer students. 

Initial observation:

Here at the Primary Testing Facility, we are fans of easy & delicious food. While slow cookers advertise themselves as producing moist, tender, roasts upon returning home from work (or a long, arduous day of not working), we have noticed that longer does not seem to equate to better. Often, our day-long slow cookery ends up producing seemingly dry meat.

Question:

At what point in the slow cooking journey are meats the “best”?

Expectation:

It is expected that there is a simple gradient from raw to dry, with the 8 hour cook time being generally dry (based on previous experience). Somewhere in the middle should be a “best” result. Mass loss results indicate that this may be around 4 hours.

Equipment & Materials:

• resulting meat & veg from the “Temporal Effects of Slow Cooking on Beef” experiment
• 8 sample cups, labeled with tape
• willing taste testers

Procedure: (note: steaks will be referred to by #, which corresponds to their cooking time in hours)

1. since the steaks from the related mass experiment were stashed in the fridge as they were sequentially removed from the slow cooker over the course of the 8 hours, these needed to be warmed
2. the sauce and vegetable matter were still in the crockpot after the removal of steak #8. Being quite hot, this fluid was used to re-warm the steaks by placing each in the hot fluid for around 1 minute
3. to keep track of the steaks, and help ensure equal warming time, they were placed in the warming liquid two at a time in a regular order (e.g. start with the 1- and 2-hour steaks, place #1 on the left side, and #2 on the right. When doing steaks 3 & 4, place #3 on the left and #4 on the right, etc…)
4. the warmed steaks were removed to a cutting board cut
5. each steak was cut into bit-sized cubes and placed into cups that were  labeled such that it was easy to identify which sample it contained (you know, like how many hours each sample was cooked)
6. consumption & note taking commenced
7. (optional)  left over beef cubes were mixed with veg & sauce to create a (texturally variable) stew for later consumption

Meat cut up and ready for tasting. Top row left to right: 1 hour, 2 hours, 3 hours, 4 hours. Bottom row left to right: 5 hours, 6 hours, 7 hours.

Results:

1 hour: as expected for medium rare (more or less), which is unexpected from a crock pot. Good beefy flavor, tender, but hard to poke with a toothpick.
2 hour: looks approximately medium, though requires more effort to chew than expected. Still has a nice flavor, but definitely tougher than #1.
3 hour: drier than at 2 hours, tough, and reminiscent of food service/cafeteria bulk-cooked steak
4 hour: rather tough and generally underwhelming, though slightly nicer flavor (more pot-roast-y) than #3 . Texture is dry and tight.
5 hour: dryish but not  especially tough, perhaps a bit bland. Fibers are beginning to separate. Drier than  #2 , but fiber texture makes it seem less dry than the steak sample #4. This steak has a more developed flavor than specimens 2, 3, & 4.
6 hour: much like hour 5, but texturally more open (fall apart-y).
7 hour: falls apart with minimal force, but dry. Noticeable “veg flavor” (possibly from the carrots).
8 hour: dry, and looser than #7. Good flavor but “like a beef desert”. May explain the use of catsup/ketchup on pot roasts in some regions….

Surprise Results (if any):

The one hour steaks were very nicely done… this could be a good method of cooking medium-rare steaks for a crowd. Instead of a simple change from raw to overdone, there was a step-like progression from yum -> blech -> Mmmm… -> “can I have some water”?.

Discussion:

The standard progression during cooking according to McGee’s glorious book (On Food and Cooking: The Science and Lore of the Kitchen) is as follows:

120°F: myosin begins to contract and squeeze out moisture. Steaks served at this temperature (rare) would be firm due to the myosin contraction, but juicy.

140-150°F: meats will release an abundance of fluid between these temperatures, and will thus shrink and become chewier. Changes in this temperature range are caused by the shrinkage of collagen. These changes will progress the meat towards a “drier” state. This matches with the mass loss seen between steaks #1 and #2.

Between the above stage, and the conversion to collagen below, the meat will become progressively more tough and dry.

160-170°F the collagen begins to dissolve and forms gelatin (gelatin is formed by the unwinding of the collagen structure). The connective tissues thus soften, and the compacted muscle fibers loosen. This causes the meat to seem more tender than before. This is the temperature range where collagen begins to dissolve, and the process increases as temperature does. At 200°F it happens at quite a fast clip.

Conclusion:

The “sweet spot” for this cut of meat in OUR slow cooker seems to be around 5-6 hours. It is important to note that slow cookers can vary widely in their temperatures and cooking characteristics, so your results may vary! We suspect our crock pot is getting too hot for the “low” setting, which is likely contributing to the issues regarding dry meat at 8 hours. You can cook meats for many hours using sous vide techniques, but because temperature is so tightly controlled in that case, you can end up with amazing results with 72 hour cook times.

The temperature from the third hour on in this experiment, was in the collagen-gelatin conversion range. It is assumed that it took some time for the conversion to complete. Steak #3 was the first one pulled after entering the conversion range, and likely had minimal conversion due to the lack of time at that temperature. Beyond steaks #5 & #6 it is suspected that too much of the gelatin was dissolved into the surrounding fluid (escaping the steaks), making the meat increasingly drier but more fall-aparty.

Future Questions:

Does the 5-6 hour sweet spot hold for larger, fattier, or bone-in cuts of meat?
Based on the related work by Belle Lowe, it is stated that acids can speed up the process. How then, does cooking in a acidic fluid alter the slow cooking results, if at all?
Is there a difference between the timer and non-timer settings on how the crockpot heats up? (some recent observations indicate this might be possible)

Related Work:

Bogue, Robert H. (1923). Conditions Affecting the Hydrolysis of Collagen to Gelatin. Ind. Eng. Chem., 15 (11), pp 1154–1159.
Lowe, Belle. (1937). Experimental cookery, from the chemical and physical standpoint. New York, J. Wiley & sons, inc.; London, Chapman & Hall, limited. 628 pp.
Sciencegeist (March 4, 2011). Slow Cooking.