Masking bitter flavours

A major hurdle when replacing salt is the significant and intense chemical / bitter flavours that are clear when using salt substitutes. Humans have 25 identified different bitterness receptors on our tongues. Historically, this is very useful because in nature, most bitter compounds are toxic so our ability to detect bitterness is a matter of survival! Moreover, the bitterness taste has absolutely nothing to do with the saltiness taste. So they can (and do) change independently.

Research shows that many chemicals help us cover bitter flavours in foods, especially those related to salt substitutes. For example:
• nucleotides (see enhancement of saltiness blog 3) increase the impact of MSG
• adenosine monophosphate reduces KCl bitterness
• some companies produce special confidential flavour additives that block bitterness
• yeast hydrolysates help disguise bitterness

There is a lot of research known and still being conducted into bitterness blockers and maskers. These are designed to fool our tongues and to make sure many of these 25 bitterness receptors on our tongues simply don’t notice anything at all.

Novel introductions of sodium replacers

Everyone working with salt reduction tends to use sodium as the best indicator of the salt content. In fact, not all sodium in foods comes from salt. So there has been another series of new products introduced to replace sodium as opposed to replacing salt as such. .

For example:
• replacement of sodium bicarbonate in baking with potassium bicarbonate
• modification of polyphosphates in meat products to reduce the amount of sodium in the chemical structures

In addition there are some dairy salts that can help in enhancing saltiness in foods and these are replacing sodium chloride.

We are starting to see a range of new modified chemicals like this coming into the industrial marketplace, specifically to replace sodium in formulations.

For people with CKD, many of these ingredients / additives contain potassium, or phosphorus. These changes create more challenges and especially hidden problems, as neither of these chemicals is required to be identified or quantified on any consumer label.

Increasing saltiness delivery

We know a lot about salt taste and how to maximise it by providing an intense salt hit on our tongue. Let’s look at some ways this can be done using smart new technologies.

For products that contain solid salt particles (such as potato crisps), the finer the particles, the saltier the taste. Hence and the larger and more visible the grains of salt the less salt taste. The big crystals of salt don’t even dissolve in the mouth before it has passed the tongue and been swallowed.

Technology means we can now make ultra-fine particles of salt, which you may hear described as nanosalt. Although they are so small as to be invisible, they have a huge impact on perception. The taste is extremely salty, even in very low concentrations. Changing from big salt crystals to ultrafine salt can easily result in more than 50% reduction for the same salty taste! This technology has just been patented by UK researchers and will be available from Tate & Lyle sometime in 2012.

In most food the salt is already dissolved and is normally distributed throughout the product. Clever researchers in The Netherlands have managed to make bread which has layers of salt. While the majority of the bread has almost no salt at all, some layers have a high level. When we eat the bread, these salty layers give a salt hit on the tongue and we think all the bread is salty. In actual fact, the overall salt content of the bread can be very low.

Another new technology is to create different concentrations of salt by using emulsions. Emulsions are naturally common in food; they are fat and water mixtures, such as butter, margarine, mayonnaise etc. Salt is only soluble in water, not in fat. We can make one water-in-fat emulsion (ie small droplets of water, surrounded by fat) which has no salt. Then use this to make a second emulsion using a small amount of salty water. The new, combined emulsion tastes salty, as we taste only the salty water, while the bulk of the product has no salt at all. In fact, the overall salt content of that combined emulsion can be extremely low.

The background to this type of salt reduction is smart food manufacture. This is truly salt reduction (not substitution) and the food products are very advanced. While this is still experimental, there are some exciting prospects for future development.

Salt replacement

Whilst we have really good replacers for fats and sugars, there are no good substitutes for salt.

Our best opportunity is with potassium chloride (KCl). Unfortunately this has a bitter, chemical taste and many people cannot tolerate it. Among the many proprietary salt replacers on the market almost all use KCl to replace SOME of the salt. They contain other additives, such as magnesium sulphate, ammonium chloride, MSG and amino acids. All these additives must by law be clearly stated on the labels of these salt replacers as you can buy them in the supermarkets.

However, two things are important to note:
• these salt replacers still contain sodium chloride, normally as the primary ingredient (so you only reduce salt, not replace it!)
• these formulations almost always contain large amounts of KCl which can be dangerous for people with chronic kidney disease because of the potassium. For historic reasons, potassium is not normally declared on nutrition information panels, so you will never know it’s there. See a further note below.

As alternatives to KCl, some manufacturers (especially industrial food manufacturers) reduce the sodium chloride concentration in food and replace it with calcium chloride, magnesium sulphate, or some very special (and expensive) salts containing a lot less sodium chloride.

This brings me onto a serious MYTH. Some people, especially chefs, have been promoting sea salt as being low sodium. The various salts you can buy, whether sea salt, rock salt, big granules of salt or superfine salt, ALL contain the same amount of sodium chloride and all work exactly the same way, giving you exactly the same sodium content per gram in your food, all of which has the same activity in the body. The marketing and promotion of differences is completely without scientific evidence or fact. In particular, large, visible grains of salt on the food may not fully dissolve in the mouth so the food tastes less salty than it really is.

There are however two types of special salt that contain only 40-50% sodium chloride, the balance being mineral salts from the sea. These salts are:
• Oshima Blue (Japan)
• Icelandic sea salt (40% sodium chloride)

They are made using very special processing techniques and by analysis can be proven to contain less than 50% sodium chloride. You don’t find these salts in the supermarket or your specialty salt shop, and if you can find them, they are jolly expensive.

Finally, a special warning for people with chronic kidney disease. Some food manufacturers use salt replacers (especially containing KCl) to reduce sodium content in their manufactured foods. While the labels show a reduction in sodium, they do NOT quantify the increase in potassium. In fact, it may not even be clear on the label that a salt replacer has been used at all.

If you are required to reduce potassium in your diet (as many of us are required to do) this is now becoming a very significant source of new and hidden potassium in the diet. Food manufacturers are so busy promoting ‘low salt’ or ‘low sodium’ that they dont always make it clear HOW they have managed to do this. Be careful! Look for transparency in labelling: if reduced sodium has been claimed on the label, has the manufacturer put the content of potassium in the nutrition information panel?

Enhancement of saltiness

It is possible to use food additives other than salt to give the sensation of increased saltiness. While these additives themselves are not necessarily salty, they make salt taste saltier. By using such additives, the amount of salt can be reduced, but the salty taste remains roughly the same. These additives are used extensively as flavour enhancers. They include:

Amino acids
glycine
L-lysine and L-arginine
hydrolysed protein
amino acid mixtures
glutamates (especially MSG)
L-ornithine
dipeptides, tripeptides

Nucleotides
5ʹ-ribonucleotides
disodium guanylate
disodium inosinate
inosine 5ʹ-monophosphate (IMP)
5ʹ-guanidyllic acid

Lactates
sodium, potassium and calcium lactates

Trehalose

Alapyridaine
(N-(1-carboxyethyl)-6-hydroxymethyl-pyridinium-3-ol)

Each has its own unique set of E numbers, but they can also be disguised on food labels in terms such as ‘meat hydrolysates’, or ‘vegetable hydrolysates’.

Just because they are called food additives they are not necessarily bad or unnatural. Many are completely natural. For example, the lactates are chemicals found in fermented dairy products (cheese, yoghurt). Glutamate, which has mistakenly obtained a bad press as MSG, is in fact the most common amino acid (protein building block) in foods and in our bodies. It is the single most common amino acid in our blood and is the one that passes our blood:brain barrier. MSG is naturally high in foods such as tomatoes, mushrooms and many vegetables.