Q: "Can you explain the difference between boiled and cooked bone in a =
little more detail?  My vet wants to know more."
 
Take out a sheet of paper.  On the long side, near the edge, draw a
straight line (horizontal axis).  Now, draw a simple, standard "bell
curve" along the horizontal axis.  Draw a vertical line so it intersects
the peak of the bell curve.  Label the left side of the paper "DRY
COOKED," and the left side of the horizontal line "HARD." Label the right
side of the paper "WET COOKED" and the right side of the horizontal line
"SOFT." Label area where the vertical line intersects the horizontal line
"RAW." Label the horizontal line (axis) "TIME." Label the vertical line
(axis) "DEGREE OF CHANGE."
 
Ok, the vertical axis represents 0 (zero) time, and the farther you move
right or left from the line, the more time has taken place, so that equal
distances represent similar times.  In other words, 3 inches to the left
represents the same amount of time as 3 inches to the right, and so
forth.  The horizontal axis represents the degree of change, so as you
move down the slope of the bell curve, you have more change towards
'soft' or 'hard.'
 
When you DRY cook bone, you drive off moisture, carbonize the collagen,
and basically do to the bone minerals the same thing you do when you
fire clay to make a ceramic.  Dry cooked bone is harder, brittle, more
crystalline, and fractures like glass.  It will ping when struck by
metal.  If you continue to dry cook the bone, it starts to shrink, and
will start to crack and fall apart in a pattern reminiscent of the type
of cracking seen when mud dries--basically in a rectangular pattern.
When you WET cook bone, you inject moisture, denature the collagen, and
dissolve bone minerals.  Wet cooked bone is softer, porous, chalky, and
crumbles under pressure.  It will thunk when struck by metal.  If you
continue to wet cook the bone, it starts to dissolve, and will become so
porous that it will actually smear between your fingers.
 
Now, look at the bell curve.  As you can see, for very short cooking
times, either wet OR dry, the changes to the bone are insignificant, and
the bone acts as if it was green (or fresh, or raw).  After a while, the
bone begins to change while under the influence of dry or wet cooking,
and it continues to change, getting harder or softer until the reactions
essentially bottom out, and continued cooking results in little
difference in hardness or softness.  What this graph shows you is the
longer you dry or wet cook bone, the more pronounced the change in the
characteristics of the minerals.  It also has one very important
implication: boiled bone does not become harder than fresh bone.  There
is never a time when boiled bone moves toward the side of the bell curve
where it gets harder.  It also means the longer you dry cook bone, the
harder it becomes, but for short dry cooking times, the difference
compared to raw bone is minor.
 
If your vet is interested, have them email me directly and I will send
them a real graph with times and data points.  The graph, as I have
described it above, is slightly skewed from reality to preserve my data
for publication.
 
Bob C
[Posted in FML issue 4165]