In order to determine whether there was any difference in regard to the
penetration of the pickling fluids in the sour hams as compared with
sound hams, a series of four sour hams were subjected to a chemical
examination in comparison with four sound hams. All were sweet-pickle
hams and were obtained from the same packing establishment. They were
all of the same cure and the same approximate age (i. e., length of
cure) and the same approximate weight.
In taking samples for chemical analysis, the following procedure was
adopted: A section about 2½ inches wide was cut from the center of
the body. The two ends of this section were then trimmed off along
the lines L-M and N-O, as shown in figure 2. Beginning at the skinned
surface, four slices, A, B, C, and D, were then made, as indicated by
the dotted lines. Slice B contained the bone in each instance. Slice
D was practically all fat. Each slice was ground separately in a meat
chopper and the sample thoroughly mixed before taking out portions for
analysis.
[Illustration: FIG. 2.—Cross section through body of ham to show method
of sampling for chemical analysis. A, slice below bone; B, bone slice;
C, slice above bone; D, fat slice.]
As all of the hams examined were mild-cure hams, that is, had been
pumped in the shank only, the pickling fluids in order to reach the
bodies of these hams had to penetrate chiefly from the skinned surface
of the ham, as little if any penetration takes place through the thick
skin of the ham.
The analyses[3] shown in the following tables therefore indicate the
degree of penetration of the pickling fluids.
[3] These analyses were made by Mr. R. R. Henley, of the Biochemic
Division, Bureau of Animal Industry.
_Analyses of sour hams._
───┬────────────┬──────┬───────────┬───────────
No.│Description.│Slice.│ NaCl. │ KNO₃.
───┼────────────┼──────┼───────────┼───────────
│ │ │_Per cent._│_Per cent._
1 │Sour body │ A │ 6.18 │ 0.175
│ │ B │ 4.83 │ .224
│ │ C │ 3.65 │ .299
│ │ D │ 1.03 │ .074
│ │ │ │
2 │ do │ A │ 5.34 │ .174
│ │ B │ 3.70 │ .150
│ │ C │ 2.79 │ .174
│ │ D │ 1.12 │ .012
│ │ │ │
3 │ do │ A │ 5.04 │ .125
│ │ B │ 4.08 │ .149
│ │ C │ 2.72 │ .099
│ │ D │ 1.19 │ .048
│ │ │ │
4 │ do │ A │ 7.78 │ .250
│ │ B │ 5.31 │ .100
│ │ C │ 4.76 │ .200
│ │ D │ 1.96 │ .048
───┴────────────┴──────┴───────────┴───────────
_Analyses of sound hams._
───┬────────────┬──────┬───────────┬───────────
No.│Description.│Slice.│ NaCl. │ KNO₃.
───┼────────────┼──────┼───────────┼───────────
│ │ │_Per cent._│_Per cent._
1 │Sound │ A │ 5.80 │ 0.211
│ │ B │ 4.83 │ .188
│ │ C │ 3.86 │ .221
│ │ D │ 1.33 │ .063
│ │ │ │
2 │ do │ A │ 4.94 │ .197
│ │ B │ 4.08 │ .149
│ │ C │ 3.05 │ .223
│ │ D │ 1.56 │ .059
│ │ │ │
3 │ do │ A │ 5.92 │ .173
│ │ B │ 4.29 │ .099
│ │ C │ 4.12 │ .139
│ │ D │ 2.32 │ .049
│ │ │ │
4 │ do │ A │ 5.53 │ .119
│ │ B │ 4.89 │ .079
│ │ C │ 4.32 │ .099
│ │ D │ 2.19 │ .041
───┴────────────┴──────┴───────────┴───────────
Taking an average of the four slices in each ham so as to get an
average for the entire ham, and comparing the sour hams with the sound
hams, we have the following comparison:
NaCl. KNO₃.
Average for 4 sour hams (entire ham) per cent. 3.84 0.143
Average for 4 sound hams (entire ham) do 3.93 .131
These figures show practically no difference between the sour and the
sound hams as regards the sodium chlorid and potassium nitrate content
of the entire ham.
If, now, we compare the bone slices—and these afford really a better
basis for comparison, as in sour-body hams the souring is always more
pronounced around the bone—we have the following figures:
NaCl. KNO₃.
Average for 4 sour hams (bone slice) per cent. 4.48 0.155
Average for 4 sound hams (bone slice) do 4.52 0.129
Here, again, we find no essential difference between the sour and the
sound hams, and we must conclude from these analyses that souring does
not depend upon or result from a lack of penetration of the pickling
fluids.
It seems probable that in mild-cure hams, which are pumped in the
shank only, the souring begins in the upper portion of the shank and
extends upward along the bone into the body of the ham, and that it
takes place before the pickling fluid has penetrated to the interior
of the ham. When the pickling fluid reaches the interior of the ham
it tends to inhibit the souring, which, as will be shown later, is
due to the development of bacteria within the bodies of the hams. The
growth of the bacteria, however, within the bodies of the hams and the
histological changes in the muscle fibers do not seem to interfere with
the penetration of the pickling fluids.