The chemistry of sausages!

Do you like sausage ? Salami ? Meat ? Ham?

And do you know what come together with them ?

Food additives ...

Widely used to prolong life´s food sodium nitrite/nitrate is added into these products. 

For centuries humans has been preserving their food with the use of salts in order to prevent growth of certain types of bacteria that cause spoilage. Indeed, in presence of this salt, bacteries find a dry environment and die. 

Sodium nitrite delays growth of anaerobic bacteria, such as Clostridium botulinum, avoiding the rancidity and also prevents the release of bad odors during storage of the products.

But is it possible to know if is there nitrite/nitrate in certain product when you buy?

Yes! Pay special attention to the color. If it is pink is because there is nitrite/nitrate in your sausage, salami or ham.

And why is pink?

I'll explain :

Basically sodium nitrite/nitrate ( NaNO2/ NaNO3 ) is converted to nitric oxide (NO). This oxide combines with myoglobin , the protein responsible for transporting oxygen and gives the natural red color of meat . The result is the formation of a complex called nitric oxide myoglobin that keeps this red color longer.

According to the Committee of Experts on Food Additives ( JECFA - " Joint Expert on Food Comitte Aditives ) FAO / WHO ( Food Agriculture Organization / World Health Organization) were reassessed IDA limits to nitrite and nitrate ions. The acronym IDA is defined as the amount of a substance expressed in mg/kg body weight , that can be ingested daily for all of your life, without causing harm to human health .

Therefore, the IDA values established for sodium nitrite are 0 to 0.07 mg/kg body weight and nitrate ions limits are 0 to 3.7 mg/kg body weight. According to the literature a lethal dose of nitrite was 330mg/Kg body weight.

The problems caused by excessive intake of nitrite and nitrate is the possible formation of methemoglobin and the formation of N-nitro compounds.

Little complicated these names, isn´t?

Let´s understand it:

These ions are absorbed by the gastrointestinal tract (stomach and intestine system), but nitrate is rapidly eliminated by renal system (kidney) . Nitrite combines with hemoglobin , the blood that carries oxygen cell by oxidation of ferrous ion to ferric ion . When this happens there is the formation of methemoglobin ( MetHb ) preventing oxygen transport. However, for our lucky, another enzyme called NADH-Methemoglobin reductase, which is found in red blood cells, converts them back into hemoglobin .

As you can see , this process is reversible . At low concentrations. Higher levels , this reduction system becomes saturated, and therefore raises blood levels of MetHb.

It is noteworthy that in children under 3 months of life, this process is very fast. Only a few grams is necessary to intoxicate a baby. So, all mothers who is reading this text, it would be advisable not eat so many products like these, in the period of breastfeeding.

Normally nitrite is eliminated by urine, which can be observed by its color change when you eat some hot dogs, for example. However, when nitrite poisoning occurs, the most common symptoms are: abdominal pain , dyspepsia, headaches and weakness. There are studies that relate intake nitrosating compounds (nitrate and nitrite) and intragastric formation of N -nitrosamines with gastric, liver and esophageal cancer.

There are some products at grocery stores without these preservatives, but it is better for you avoid them anyway. But if it's too hard do not resist a sausage or a hot dog take some following precautions :

1 ) Read the label. Sodium nitrite sometimes appears with the acronym E250 and E251 for sodium nitrate. Try to identify them and reduce their consumption ;

2 ) Increase your intake of antioxidants and garlic foods because they have chemicals that inhibit the formation of nitrosamines ;

And boil the product. So you pull out of some ammounts of preservatives and helps kill remaining bacterias.

Hope it helped you! It is just a tip!

You are what you eat! ;)

Barbara Francisco
Industrial chemistry


References :
DUARTE , MT Evaluation of the sodium nitrite content liguiças frescal and baked kind sold in the state of Rio de Janeiro . 2010.
SCHUDDEBOOM , Nitrates and Nitrites in LJ foodstuffs . 1993
Epley , R.J ; ADDIS , P. B. ; WARTHESEN JJ Nitrite in meat . Animal sceince.1992