The Use of Sodium Nitrite in the Curing of Meat

The art of preserving meats by curing in common salt, with or without smoking, is one which has been practiced from remote antiquity. Directions for curing meats with salt appear in ancient writings, and the art is still practiced among primitive peoples. Yet, notwithstanding the antiquity of the art and its economic importance, adequate and comprehensive scientific study with publication of results has never been given to it. Even at the present time the scientific publications on the subject consist largely of recipes and formulas or the results of desultory and isolated experiments. The use of nitrates also dates from ancient times, and has been practiced so long that its origin is unknown (#, p. 613). Only within recent years, however, has the function of nitrates been correctly understood. The investigations of Haldane (1) and Hoagland {3, 4) demonstrated that this function is the fixation of color which takes place through the reduction of nitrate to nitrite, and the combination of the latter with the hemoglobin of the meat. McBryde (7) showed that potassium nitrate has no more preservative power than common salt when tested against the organisms concerned in the spoilage of hams. Present scientific knowledge, therefore, indicates that nitrates are useful only as color fixatives and that their aid in preservation is not of importance. The nitrates, as such, are without value as color fixatives and become active only when reduced to nitrites. In practice this is proved by the fact that if the formation of nitrites is prevented or interfered with in any way the color fixation is likewise prevented or interfered with. Unsatisfactory or insufficient formation of nitrite invariably results in unsatisfactory, inadequate, or irregular fixation of color. So far as color fixation is concerned, the progress of curing in a vat of meat in pickle may be followed by determining the nitrite content of the pickle. A The formation of nitrite was ascribed by Haldane (1) to bacterial action. This opinion is evidently correct, as there are several circumstances connected with practical meat curing which are best explained on the assumption that the nitrate is reduced by bacterial action. Among these are the variability of the cure, often observed in a new establishment, the advantageous results obtainable by adjustment and control of the hydrogen-ion concentration of the pickle, the benefits derived from "seeding," and the occasional failure of nitrite formation caused by development of acid-forming organisms in the pickle.