Ammonia is a household and industrial cleaner that has an unpleasant and bitter odor. Sometimes food has a similar odor, which can be a normal part of its production, or it can be an indication of serious problems with the quality of the food. Smelling an ammonia-like odor that is not actually present can also be a symptom of health problems.
Food processors will sometimes treat meat products with ammonia to kill bacteria such as E. coli and Salmonella. Ammonia is not listed on these food labels because it is a processing agent and not an ingredient of the food. This can affect the taste and smell of food, but it is not considered a health concern after the Food and Drug Administration found that ammonia is safe to be used this way.
Some cheeses, meat and seafood will smell like ammonia when they are spoiled. This is because of the breakdown of the proteins, fats and carbohydrates in the foods, but it does not necessarily mean the food will be unsafe to consume. The smell and flavor of the food, however, will likely be unpleasant if the uncooked food smells strongly of ammonia, so it is a good idea to discard it if it has been in your refrigerator for a while. If the food was recently purchased and the smell is present before its freshness date, consider returning it to the store.
Ammonia smell can also be present in fermented foods. Tempeh, for example, is made of fermented soybeans and sometimes an ammonia-like smell can be detected. This is normal in fermented foods, and cooking methods will usually help eliminate the smell. Other fermented foods, such as Korean hongeo and Icelandic hakarl also have strong ammonia odors. Hongeo is rotten skate fish that is served with kimchi, salted pork belly and rice wine. Hakarl is fermented shark meat that is considered a delicacy in Iceland.
Perceiving an ammonia-like smell in your food that is not actually present may be an indication of sinus problems or a symptom of anxiety. If your food smells like ammonia to you, check and see if others detect the odor as well. If you consistently think your food smells like ammonia and others do not smell the odor, consult a doctor who can refer you to specialists who can determine the cause of this symptom.
References and ResourcesNew York Times; Safety of Beef Processing Method is Questioned; Michael Moss; December 2009
California Poison Control System: Food Poisoning and Safety
Purdue University Animal Sciences: Meat Quality and Safety
Tempeh.info: Frequently Asked Questions
Open Journey; 18 Stinky Foods from Around the World; June 2010
AnxietyCentre.com: Anxiety Symptoms - Taste and Smell Symptoms