Nitrogen is a fundamental element found throughout nature, and its presence in food and beverages has become increasingly common. The question of its safety for consumption depends on its physical form and how it is handled. While certain forms of nitrogen are entirely harmless and beneficial, others require careful management to prevent adverse effects. Understanding these distinctions is important for consumers.
Nitrogen’s Ubiquitous Presence
Nitrogen, identified by the chemical symbol N and atomic number 7, is a nonmetallic element. It is an abundant element in the universe and makes up approximately 78% of Earth’s atmosphere by volume, making it the most plentiful gas in the air we breathe. This pervasive element is also a building block for all living organisms.
Nitrogen atoms are found in proteins, nucleic acids like DNA and RNA, and other biomolecules within the human body. The human body contains about 3% nitrogen by mass, ranking as the fourth most abundant element after oxygen, carbon, and hydrogen. Animals acquire usable nitrogen compounds by consuming plants or other animals.
Gaseous Nitrogen and Its Role in Food
Gaseous nitrogen is inert, meaning it does not readily react with other substances, and is non-toxic. This makes it a valuable tool in the food industry, primarily for preventing spoilage and extending shelf life. One common application is in modified atmosphere packaging (MAP), where nitrogen displaces oxygen within food packages. Oxygen can cause food to spoil through oxidation and encourages the growth of microorganisms, so removing it helps maintain freshness, flavor, and texture.
This process is why bags of snacks like potato chips often appear inflated; the nitrogen gas cushions the contents and protects delicate items from damage during transport. Nitrogen is also infused into certain beverages, such as coffee and beer, to create a distinct texture. For example, “nitro” cold brew coffee gains a creamy, smooth mouthfeel and a cascading visual effect from the tiny nitrogen bubbles. In these gaseous forms, nitrogen is considered safe for consumption, as it is either released from the product or ingested in small, harmless amounts.
Understanding Liquid Nitrogen
Liquid nitrogen is nitrogen that has been cooled to an extremely low temperature, specifically around -196°C (-320°F). Its intense cold is its primary characteristic and also the source of its potential hazards. Direct contact with liquid nitrogen can cause severe frostbite or cryogenic burns to skin and other tissues, even with brief exposure. The extreme temperature can also cause severe damage to internal organs if ingested.
Another significant danger arises from its rapid expansion as it warms and converts back into a gas; one liter of liquid nitrogen can expand into approximately 700 liters of nitrogen gas. This rapid expansion can displace oxygen in enclosed or poorly ventilated areas, creating an oxygen-deficient environment that could lead to asphyxiation. In culinary settings, liquid nitrogen is used for flash-freezing foods like ice cream or creating dramatic “smoke” effects in dishes and drinks. However, for safe consumption, it is crucial that all liquid nitrogen has fully evaporated and the food or drink has warmed sufficiently before it is served.
Safe Practices and Handling
Safe practices are important for both consumers and those handling nitrogen in food preparation. When it comes to foods or drinks prepared with liquid nitrogen, particular care is needed. Consumers should only consume such items when served by trained professionals who ensure that all liquid nitrogen has completely evaporated before the product is handed over.
The U.S. Food and Drug Administration (FDA) has advised consumers to avoid eating, drinking, or handling food products prepared with liquid nitrogen at the point of sale, especially if any visible “smoke” or mist remains, due to the risk of injury from its extreme cold. Inhaling the vapor immediately after preparation can also cause breathing difficulties, particularly for individuals with asthma. Therefore, if you encounter a dish with liquid nitrogen still present, it is best to wait until it has fully dissipated.