Result: When tested at the end of the cure, all of these hams were found to be perfectly sound and sweet.
Results of experiment to show whether hams become infected from ham thermometers.
| No. of tierce. | Number of hams. | Average weight of hams. Pounds. | How pumped. | Treatment. | Condition at end of cure. | |
|---|---|---|---|---|---|---|
| Number of sour hams. | Percentage of sour hams. | |||||
| 1 | 20 | 12-14 | 10 in shank | Tested in several stages in preparation for curewhich had not been cleaned. | 5 | 50 |
| 10 in body and shank | do | 2 | 20 | |||
| 2 | 20 | 14-16 | 10 in shank | Tested once with ham thermometer dippedin culture suspension of anaerobic bacillus isolatedfrom sour hams. | 10 | 100 |
| 10 in body and shank | do | 7 | 70 | |||
| 3 | 20 | 14-16 | 10 in shank | Not tested with thermometer. | 0 | 0 |
| 10 in body and shank | do | 0 | 0 | |||
Several hams from each tierce were examined bacteriologically. cultures being taken from the meat near the bone and from the bone marrow of the femur.
In the sour hams from tierce 1 cultures taken from the meat near the bone showed the same anaerobic bacillus noted in other sour hams (i. e., the same bacillus which caused souring in Experiments I and II), but these cultures were contaminated with other bacteria which were probably introduced on the thermometer along with the ham-souring bacillus. None of the contaminating bacteria were capable, however, of producing a sour-meat odor when grown on the egg-pork medium. Pure cultures of the ham-souring bacillus were obtained from the bone marrow of some of these hams, showing that this bacillus had penetrated through to the bone marrow while the other bacteria had not.
From the sour hams in tierce 2 the ham-souring bacillus was recovered readily, and often in pure culture, from the hams which had been pumped in the shank only, whereas it was usually contaminated with pickle bacteria in the hams which had been pumped in both body and shank.
In the case of the sound hams in tierce 3, cultures taken from the meat near the bone and from the bone marrow of the femur were negative in the hams which had been pumped in the shank only, while cultures taken from corresponding points in the hams pumped in both body and shank showed ordinary pickle bacteria, which had evidently been introduced into the bodies of these hams in the pumping pickles. None of these hams exhibited the slightest sour odor.
Summary of experiment.—In this experiment 20 hams (tierce 1) were tested with an ordinary ham thermometer in the usual packing-house manner. Half of these hams were subjected to the mild cure and half were given the regular cure, with the result that 50 per cent of those receiving the mild cure and 20 per cent of those receiving the regular cure became sour.
A second lot of 20 hams (tierce 2) were tested with a thermometer which had been purposely contaminated with a culture suspension of the ham-souring bacillus. These hams were cured in the same manner as the first lot, with the result that all of those receiving the mild cure and 70 per cent of those receiving the regular cure became sour.
A third lot of 20 hams (tierce 3) which had not been tested at all were cured in the same manner as the two preceding lots, as a check on the cure. All of these hams were sweet at the end of the cure.