Sour hams are classed as “shank sours” and “body sours,” according to
the location of the souring, and these may be “light” or “heavy.” When
the souring is very pronounced, the ham is termed a “stinker.”
Souring appears to start, as a rule, around the stifle joint
(femorotibial articulation), and extends upward into the body of the
ham.
In quite a large proportion of the hams which are sour in the
body—probably from 40 to 50 per cent—the souring extends through to
the bone marrow of the femur or middle bone, and the sour odor is at
times more pronounced in the bone marrow than in the meat. The odor
of the bone marrow, when pronounced, is strongly suggestive of a
dissecting-room odor, and is distinctly putrefactive in quality.
In the case of light body sours the sour odor is confined to a small
area immediately around the bone, and may be so slight that it is
detected only with difficulty. In such hams the bone marrow is apt to
be sweet, and it is not until the souring becomes more extensive that
the bone marrow becomes involved.
[Illustration: FIG. 1.—Cross section through body of ham, with sour
areas indicated by shading and dotted lines.]
The distribution of the sour area in the body of a well-developed sour
is shown in figure 1.
In the case of a well-developed body sour the sour area is more
pronounced near the bone, as represented in figure 1 by the shaded
area, and may extend out into the body of the ham for a variable
distance, according to the degree of souring, as represented by the
dotted lines, gradually fading off toward the margins, where it may be
imperceptible or entirely wanting.
In the pronounced sours, termed “stinkers,” the odor pervades the
entire ham, and is of a distinctly putrefactive quality.
In shank sours, the souring is more or less confined to the shank, or
the region about the tibio-femoral articulation, but may extend upward
into the lower portion of the body of the ham.