How Does Salt Preservation Work in Meat?

[bobsmith76]

I was reading this post regarding meat preservation.
http://answers.yahoo.com/question/index?qid=20061022184303AALaiDt

Basically, salt draws out the water from meat which keeps insects away since insect are attracted to water.

There's one point that is glossed over: how does salt, which is NaCl draw out or absorb water? What is the chemical reaction that breaks water down? How does salt on the surface extract water in the center of meat?

 

[Borek]

I haven't read the linked text, so I am not going to comment on that. But salt doesn't break water down. Read about osmosis.

 

[256bits]

The salt preservation inhibits bacterial growth on the surface of the meat, whether that be from airborne bacteria landing on the surface or bacteria deposited by insects.

To some extent you do the same when you buy strawberries and coat them with sugar - it is done not just to add a sweeter taste, but to allow the strawberries to last longer.

 

[cbwerner]

There are actually a couple of variables with meat. If it is a whole muscle (i.e., not a ground sausage - salami) then salt is sufficient for curing as it will act on the exterior quickly both killing bacteria with its salinity and on the interior by drawing water from the meat by osmosis thus creating a condition where bacteria can't grow. The exception here is the fat, which while preserved can still go rancid if exposed to light for some time.

With salami, ground sausages, salt is not sufficient. Think of e coli as an analogy - you don't need to worry about it grilling a steak since it can only exist on the exterior, so grilling a steak rare is no problem. But with ground beef, where the exterior has likely moved to the interior, it's a problem, so burgers need to be cooked to at least medium to be safe.

Similarly, salami are plagued by botulism. Botulism comes from spores that create bacteria that in turn secrete the venom that causes botulism, which is a very bad disease. But for the spores to create the bacteria, they need 2 conditions - 1. temperature between 40d F and 140d F (I might be off on the latter), and 2. An anaerobic environment (no oxygen) - i.e., the inside of a sausage.

Salt is not sufficient here (still used, but needs some help). To kill the spores requires sodium nitrite, which is delivered either directly as sodium nitrite or in combination as that plus sodium nitrate in longer curing sausages as the nitrate decomposes to the nitrite which is the actual working chemical. Actually, I think the nitrite is the key as saltpeter (Potassium Nitrite/Nitrate?) use to be used way back when. But saltpeter keeps a good man down. ;)

Regardless, NaCl is the king of preservatives. If you have more curiosity on this, search on "charcuterie" - the art/science of preserving meats.


Chris.

 

[LudusRex]

I would like to clarify and expand on the process of salt and meat preservation mentioned in the post. Salt, or sodium chloride (NaCl), does not actually "draw out" water from meat. Instead, it works through a process called osmosis.

Osmosis is the movement of water molecules from an area of high concentration (in this case, the meat) to an area of low concentration (the salt). When salt is applied to the surface of meat, it creates a hypertonic (high concentration) environment, meaning that there is a higher concentration of solutes (salt) outside the meat than inside. This causes the water molecules inside the meat to move outwards towards the salt in an effort to balance the concentration on both sides. This movement of water helps to remove excess moisture from the meat, making it less hospitable for bacteria and insects to grow.

Furthermore, salt also inhibits the growth of bacteria by making the environment too salty for them to survive. Bacteria need water to thrive, so by removing water from the meat, salt effectively prevents bacteria from growing and spoiling the meat.

In terms of how salt on the surface can extract water from the center of meat, this is due to the process of diffusion. Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. As the salt on the surface of the meat draws out water, it creates a concentration gradient within the meat, causing water to move from the center towards the surface to balance the concentration.

It is important to note that the effectiveness of salt in preserving meat also depends on the type and amount of salt used, as well as the temperature and humidity conditions during the preservation process. Too much salt can actually have the opposite effect and draw too much water out of the meat, making it tough and dry.

In conclusion, salt preservation works through a combination of osmosis and diffusion, creating an environment that is unfavorable for bacteria and insects to grow. It is a simple yet effective method of preserving meat that has been used for centuries.