Charles Neil McBryde

“ Souring is detected and located by means of a pointed metal instrument known as a “ham trier,” which resembles a long, slightly flattened ice pick. The trier is thrust into the ham at different points along the bone, rapidly withdrawn, and the odor which clings to the metal noted. The trained inspector works very rapidly, and is able to detect even the slightest sour or off odor which might be imperceptible to one not trained to the work. At the end of the cure all hams are tested with the trier under the supervision of Government meat inspectors. ”

“ An average ham weighing from 14 to 16 pounds requires about 60 days to cure, and at the end of 30 days a certain number of hams in each run are usually tested to see how the cure is progressing. If no sour hams are discovered at this inspection the packer knows that the cure is progressing satisfactorily, and moreover he feels sure that his hams will finish satisfactorily, for experience has taught him that souring develops within the first four weeks of the curing period, and if his hams are sweet at the end of this time, he can feel practically sure that no sours will develop later on. ”

“ When the hams lie in the right position, with the butt or large portion away from and the shank toward the operator, it is an easy matter to pick them up in the proper manner; but when they lie at different angles and are being rapidly handled it is almost impossible to prevent the hook from penetrating the muscular tissues, and if the hook should penetrate to the bone it might carry in foreign matter contaminated with the meat-souring bacillus. It is not probable that many hams become contaminated in this way, as the men who handle the hams are very skillful in manipulating their hooks ”

“ Another theory attributes souring to a diseased condition of the meat. Prior to the enforcement of the Federal regulations governing meat inspection there might have been some ground for such a supposition, but this theory could not hold at the present time, in view of the thorough and efficient inspection now in force, for it can be safely said that no diseased meat now passes the Government inspectors, and therefore no diseased meat goes into cure in inspected houses. ”

“ Sometimes one and sometimes all of these bacteria were present in a given ham. They were encountered most frequently in hams which had been pumped in both body and shank, and were probably ordinary pickle bacteria. They were not strict anaerobes, but belonged to the class of facultative or optional anaerobes; that is, organisms which will grow either with or without free oxygen. These bacteria were isolated and grown on the egg-pork medium, but failed to give any characteristic sour or putrefactive odors, and were therefore discarded. ”

“ When hams are cured without pumping, however, the period of curing has to be materially lengthened in order to give the curing pickles sufficient time to penetrate thoroughly, and this is what the larger plants wish to avoid because of the greater space and greater number of vats which would be necessitated. The object of pumping in the larger plants, where the number of hams handled daily runs into the thousands, is to hasten the cure and thus prevent the accumulation of a great number of hams at one time. ”

“ According to this theory, souring results when the meat is chilled too suddenly, the idea being that by the rapid congealing of the juices of the meat a coating is formed on the outside of the ham whereby the animal heat is prevented from escaping from the interior, leaving the meat next to the bone at a higher temperature than the outside of the ham. ”

“ 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. ”

“ The fancy-cure hams are usually cured in a milder pickle, that is, one that contains less salt and saltpeter than the pickle used in the regular cure, although in some packing establishments the same curing pickle is used for the two cures, the only difference being the additional pumping given the regular-cure hams. ”

“ In sections stained by the Gram-Weigert method to show the presence of bacteria, a large Gram-staining bacillus was noted between the muscle fibers in the connective-tissue elements of the muscle. In some of the sections these bacilli were present in great numbers, sometimes in densely packed clumps or masses, while in other sections, or in other portions of the same section, they were only sparsely distributed between the muscle fibers. Where the bacteria were more numerous the histological changes in the muscle fibers, especially the breaking down of the nuclei, were more noticeable. ”

“ The actual curing is usually carried out in large vats which hold about 1,400 pounds of meat or some hundred hams. The hams are packed in the vats in layers and are entirely covered with the pickling solution or brine. A certain proportion is always observed between the weight of the meat and the amount of the solution. The pickling solution, or “pickle,” as it is termed, is a brine solution containing [Pg 10] saltpeter and sugar. The composition of the pickle varies somewhat with the different packing establishments. ”

“ At ten days the albumins are completely coagulated except at the surface, where there is no apparent growth; the odor is more putrefactive in nature, and the reaction of the medium is slightly acid. At three weeks the coagulated albumin splits up into fragments and appears to undergo a slow digestion, gas bubbles form in the lower portion of the culture, and the odor becomes distinctly putrefactive in character. The slow digestion of the albumin is probably due to a proteolytic enzyme elaborated by the bacillus. ”

“ A theory which is quite prevalent among packing-house employees attributes souring to overheating of the animal previous to slaughter, but tests were made by driving hogs to the point of exhaustion just prior to slaughter and curing the hams from these animals in comparison with hams taken from animals which had been rested prior to slaughter, with no difference in the cured product ”

“ In this medium the organism develops rapidly at a temperature of 20° to 25° C., giving rise to the characteristic sour-meat odor. Like the bacillus described by Klein, it also grows readily on pork-agar and pork-bouillon containing glucose, but differs from Klein’s bacillus in that it will grow, though less luxuriantly, on ordinary nutrient media—agar, gelatin, and bouillon—without the addition of glucose.
The optimum temperature for growth is 20° to 25° C. The organism does not grow at incubator temperature (37.5° C.) . ”

“ While there can be little doubt that Klein’s bacillus was the cause of the tainting in those hams which he examined, the proof would certainly have been stronger had he injected sound hams with cultures and thus proven that he could reproduce tainting experimentally by means of his bacillus. Klein examined only dry-cured hams and does not state the temperature at which they were cured. ”

“ The percentage of souring in the mild-cure hams could be greatly reduced without materially affecting the cure by pumping these hams with their own curing pickle, which is usually a milder pickle than that employed in the regular cure ”

“ Cultures were always taken from the bone marrow as well as from the meat. Novy jars were also used for obtaining anaerobic conditions in growing the cultures.
Chemical examination.—In order to determine whether the souring was connected with or dependent upon a lack of penetration of the pickling fluids to the interior of the meat, the hams were further subjected to a chemical examination and the content of the meat in sodium chlorid and potassium nitrate determined at varying depths. ”

“ In stained sections of the sour meat another striking change was noticed in the disintegration of the nuclei of the muscle fibers, which are at times completely broken up, appearing as bluish granular masses in sections stained with hematoxylin and eosin. ”

“ A small amount of fat collects at the top in the form of a fatty scum, as it is impossible to remove all of the fat from the meat before it is chopped. The fatty scum, which hardens upon standing in the cold, is now removed.
B. The whites of three eggs are mixed with 250 cubic centimeters of water. The mixture is rendered neutral to phenolphthalein by means of dilute hydrochloric acid and heated for 30 minutes in the Arnold sterilizer, with occasional stirring. ”

“ S. E. Bennett, of the Inspection Division, inspector in charge at Chicago, for the assignment of trained meat inspectors to assist in the work, as well as for kind assistance in obtaining data and material for laboratory study, and to Dr. ”