Early Juiciness: Fibers Coagulate One of
the two major contracting filaments, the
protein myosin, begins to coagulate at about
120ºF/50ºC; this lends each cell some solidity
and the meat some firmness. As the myosin
molecules bond to each other, they squeeze
out some of the water molecules that had
separated them. This water collects around the
solidifying protein core, and is actively
squeezed out of the cell by its thin, elastic
sheath of connective tissue. In intact muscles,
juices break through weak spots in the fiber
sheaths. In chops and steaks, which are thin
slices of whole muscles, it also escapes out
the cut ends of the fibers. Meat served at this
stage, the equivalent of rare, is firm and juicy.
Final Juiciness: Collagen Shrinks As the
meat’s temperature rises to 140ºF/60ºC, more
of the proteins inside its cells coagulate and
the cells become more segregated into a solid
core of coagulated protein and a surrounding