Originally Posted by joebrad
cooked using a sous vide water bath at 142 degrees (F) for about 6 hours
Uh, I think I found the problem.
You are setting that for about a mid well doneness for that steak, with potential for hitting well done. With sous vide I wouldn't go much higher than 133F, I think 130 is pretty ideal personally.
6 hours is WAY too long. I'd imagine you'd start to see degradation at that point, all the texture is probably all screwed up. Depending on the thickness of the cut, you need an hour...maybe 2, max.
Both grass fed and grain fed beef are excellent done sous vide. The type of feed will have little or no impact on the success of the sous vide application. Also, the amount of intramuscular fat has little to no impact on toughness...it has to do with how flavorful and "juicy" a cut of meat is, but not the tenderness. I mean, if that were the case then the filet mignon would be the toughest cut of meat, ya catch my drift?
Grass fed is generally "tougher" because it takes longer until market weight. The animal spends more time not only alive, but more time walking, running, eating, etc. It takes about a year to raise a cattle to slaughter on a grain fed diet, while a grass fed cow takes anywhere from 18 mos to 2 years. This means the animal is slightly tougher. However, it is by no means tough and I actually personally prefer the taste of grass fed.