- tissues
When beef is cooked slowly for several hours, heat causes changes in these tissues. Collagen gradually softens and converts into gelatin, while muscle fibers separate and become tender.
The white, stringy material you see may therefore be:
- Softened connective tissue
- Tendon or other connective tissue
- Collagen-rich fibers
- Separated muscle fibers
- Small strands of fat or other tissue
This is especially common in tougher cuts of beef that contain a lot of connective tissue.
Why Does It Happen More in a Slow Cooker?
Slow cookers use relatively low temperatures over