The term “saltpeter,” often used to refer to potassium or sodium nitrate, is shrouded in misconceptions. One enduring myth is its supposed ability to curb sexual desire, particularly in soldiers’ food. This notion is entirely unfounded. Saltpeter has no impact on libido.
However, delving into the real properties of saltpeter reveals a substance with significant, albeit complex, roles, especially in food preservation. One of the most critical aspects of saltpeter relates to its ability to combat Clostridium botulinum, a bacterium responsible for producing botulinum toxin. This toxin is one of the deadliest known to humankind, far exceeding the toxicity of cobra venom. Botulinum toxin disrupts nerve function by blocking acetylcholine, a neurotransmitter. This disruption can lead to a range of severe symptoms, from blurred vision and swallowing difficulties to paralysis and, ultimately, death. Clostridium botulinum spores are widespread and can become active in environments lacking oxygen and with low acidity, often found in improperly preserved foods. Sausages are a classic example, so much so that “botulism” derives from the Latin word “botulus,” meaning sausage.
Fortunately, the risk of botulism can be significantly reduced through the judicious use of sodium nitrite. This discovery was somewhat serendipitous, arising from the long-established practice of meat salting for preservation. Salt, primarily sodium chloride, inhibits bacterial growth by dehydrating them. Centuries ago, observant cooks noticed variations in salt effectiveness depending on its source. Certain salts were not only better preservatives but also enhanced meat flavor and color. The key was identified as potassium nitrate, or saltpeter, present as an impurity. Yet, even more precisely, the active agent is not nitrate itself but nitrite, a derivative of nitrate. Certain salt-resistant bacteria present in meat can convert nitrates into nitrites. This realization led food processors to directly utilize sodium nitrite as a more efficient preservative. The chemistry is even more nuanced: the true functional component is nitric oxide, a product of nitrite decomposition. Nitric oxide is responsible for the characteristic color of cured meats and effectively eliminates botulism-causing bacteria. Despite these benefits, concerns have emerged regarding the potential health implications of nitrite exposure.
The unease regarding nitrites as food additives surfaced in the 1960s when researchers observed liver failure in animals fed nitrite-preserved fishmeal. The culprit was identified as nitrosamines, compounds formed through chemical reactions between naturally occurring amines in fish and sodium nitrite. Nitrosamines are potent carcinogens, raising immediate alarms about their potential presence in human foods. Investigations into nitrite-treated foods confirmed nitrosamine formation under specific conditions. Fried bacon, particularly when cooked to a crisp, consistently showed nitrosamine presence, as did hot dogs. Surprisingly, beer was also found to be contaminated. The source of nitrosamines in meat was relatively clear: protein breakdown during cooking releases amines, which then react with nitrites. The beer contamination was traced to the flame drying of malt. Heated air can cause nitrogen and oxygen to react, forming nitrogen oxides, which can then interact with amines in malt to produce nitrosamines. Brewers were able to resolve this issue by modifying the malt drying process to prevent direct flame contact.
Addressing nitrosamine formation in cured meats proved more complex but achievable. Adding ascorbic acid (Vitamin C) or erythorbic acid during processing can effectively inhibit the reaction between nitric oxide and amines. These additives also enhance nitrite’s preservative action by promoting its conversion to nitric oxide, allowing for lower nitrite usage. Consequently, nitrite levels in food products have been progressively reduced, with most now containing less than 100 parts per million, minimizing nitrosamine formation within the food itself.
However, a lingering concern is the potential for nitrosamine formation within the human body. We ingest both nitrites and amines through our diet, and the acidic environment of the stomach could facilitate their combination into carcinogenic nitrosamines. Some epidemiological studies suggest this is not merely a theoretical risk. A Swedish study indicated that consuming processed meats more than three times a week was linked to a notable increase in stomach cancer risk compared to those consuming less than 1.5 servings weekly. While the direct relevance to pet food isn’t explicitly detailed here, these findings underscore the broader considerations surrounding nitrite and nitrate usage in food production and their potential health effects across species.
