Merely: the salt

Certain things we do every day may seem so simple. For example, all we have to do in order to get a cup of coffee is to press a button and wait for a couple of moments. Another thing we consider simple, is salting of meat. It takes almost no effort and such a short time to be done. It is as simple as that.

But if you look behind the cover, you could find plenty of things making it everything but simple – blending the coffee in the exact ratio, pulvering it to the defined grain size, boiling the water, mixing it with milk, sugar and finally piping through the pump system to the cup – to name just a few. And there is so much happening behind this simple act of adding the salt.

Before we take a closer look at the salting process, it’s good to know why the salt (sodium chloride NaCl) is such an important ingredient.

Salt has a long list of beneficial effects on the food. For instance, the salt extends the freshness and shelf life of the food products. If we talk about details, the salt is responsible for lowering the water activity and by doing so the growth of microbes is prevented or significantly inhibited.

Salt is interactive

As we go further, we come to the taste of the food. Food differs not only in the degree of saltiness, but also in the intensity of other present tastes. This is because the salt ions are interacting with proteins, fat and other food compounds. Through this interaction, the structure of food compounds is often changed into the “tastier” configuration, making the salted food often more delicious than the unsalted counterpart. Besides the taste, the texture of the food can also be changed; for example the higher tenderness of the beef is achieved by the addition of salt in the combination with other procedures.

Salt is harmful

On the other hand, if excessively consumed, NaCl has a malicious effect to the human health. It may cause the increase of blood pressure, leading to a higher risk of heart attack. Talking in figures, the average salt consumption is 9 g/day, whereas WHO recommends 5 g/day. According to the data of health research organisations, approximately 95 % of adult men and 75 % of adult women exceed the upper limit.

The main sources of salt in our food are meat products (such as ham, sausages etc) and bread. This leads to conclusion that the content of the NaCl should be lower, which will diminish the delicious taste and longevity, and most probably increase the costs of production.

Is salt replaceable?

An alternative is to find an appropriate substitute for NaCl, which again is not an easy task, due to all the pros this mineral has. The aim of this substitution is to keep the “good” effects achieved (low bacterial growth, tenderness, taste etc) while removing the “bad” ones that can lead to health issues. While much is known about effects of salts on microorganisms and sensory properties, little is known about effects of substitute salts on food matrix, which are responsible for food texture, taste and water holding ability. A better understanding of the interaction of salt with the bio-molecules present in food, is one of the ways that can lead to the solution. This brings us back to the complexity of a food matrix.

Salt-water–proteins game

From the large group of bio-molecules present in food, we’ll focus on proteins in this article. When talking about interaction of NaCl with the food proteins there are 3 leading “players” – protein molecule, salt ions and water molecules. The water is of course inevitable, since it’s involved or even responsible for most of the processes in the living world. The proteins are bio-molecules with a long list of very complex functions, and their function is tightly connected to their structure. The protein structure again is highly affected by the versatile water molecules and the other highly charged particles, such are the salt ions. This structure influence is also working well in the different directions; the structure of salt ions is affected by water and so on. So this is a game of 3 “players” in which each of them affects the rest and is being affected by the rest in return. It is obvious that it’s not easy to determine which change is caused by one “player” and which is due to the combination of two or even all three.

Detective techniques

The area of protein-water-salt interaction has been studied and investigated for decades. Nonetheless, there are many theories that are trying to give an appropriate explanation, often disagreeing with each other. In the process of unscrambling this interaction, many powerful techniques of analysis have been applied. These techniques are developing rapidly together with the technology development.

Nowadays we have spectroscopic techniques (such as Raman spectroscopy, infra-red spectroscopy, neutron spectroscopy etc.), magnetic resonance techniques, and diffraction of X-rays, just to name a few of them. Each of these tools is able to provide us with a part of the whole image. Just like in a jigsaw puzzle, to build up the whole image, all the peaces that are gained from each of the techniques should be matched properly, in tune with the other pieces.

Detective magnifying glass: one of the instruments that are being used for unraveling the details of protein-salt-water interaction is this infra-red microscope.

Looking for a good substitute

One of the research projects (entitled LowSalt) in Nofima in Ås (The Norwegian Institute of Food, Fisheries and Aquaculture Research), is focused on this particular topic. This research is being conducted through collaboration with Sintef (Trondheim) and various Norwegian food industry partners (Mills, Nortura, Stabburet, SPIS-Grilstad, Finsbråten, Brødr Remø, Berggren). More precisely, in this research various analytical methods are used to further investigate the interaction between salt ions and meat proteins. The main idea is to better understand what is actually happening when NaCl is added to the meat, to further elucidate the interaction between salt ions and proteins. At the same time, the effect of NaCl is being compared to the effect of the salts that are taken as possible NaCl substitutes. In this way, the appropriate substitute should be chosen on the basis of the similarity with NaCl regarding the effect on the protein structure. The structure of proteins again is, responsible for many macroscopic qualities of the food that we are able to perceive.

Eventually, the appropriate substitute will be found, which will most probably be able to provide the beneficial effects to the food structure, its shelf life, taste, etc. On the other hand, the effects of that substitute to the human health are yet to be determined, especially if we continue with exceeding the necessary doses. So – it’s not as simple as it may seam, it’s not just the simple table salt- it’s actually quite complicated.

Raw materials and process optimisation  

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