The science of salt reduction in food
how can this compound - so important in the preparation and storage
of food - be replaced without the consumer tasting the difference?
The health implications of high salt intake are backed up by research from a wide range of sources.
Numerous scientists are convinced that high salt intake is responsible for increasing blood pressure (hypertension), a major risk factor for cardiovascular disease (CVD) - a disease that causes almost 50 per cent of deaths in Europe.
CVD is reported to cost the EU economy an estimated € 169bn ($202bn) per year.
In the UK, Ireland and the USA, over 80 per cent of salt intake comes from processed food, with 20 per cent of salt intake coming from meat and meat products, and about 35 per cent from cereal and cereal products. Reduction of salt in these products represents a major technological and safety challenge to producers.
Despite the obvious impact on taste, salt performs a wide variety of other functions. In processed meat products, for example, salt is involved in activating proteins to increase water-binding activity, improves the binding and textural properties of proteins, helps with the formation of stable batters with fat, and also extends shelf-life with its anti-microbacterial effects.
Eoin Desmond, research manager at Irish blending company AllinAll Ingredients and author of a new review in the journal Meat Science (doi: 10.1016/j.meatsci.2006.04.014), told FoodNavigator.com that the reduced salt product market is still niche with cost being a major, if not the major, obstacle for low-salt products.
Despite these current restrictions, the technology is developing, and according to Desmond, there are three initiatives available to reduce the salt content of meat products, each with technological limitations and considerations.
The first option is the use of salt substitutes, most notably potassium chloride (KCl). However, blends of half-half KCl-NaCl have metallic, bitter tastes with markedly less 'saltiness'. Replacement blends of the salts in the range 25 to 40 per cent potassium appear best to avoid noticeable impacts of the flavour.
Higher concentrations of KCl can be used, but masking agents need to be added to cover the adverse taste.
Commercial low-sodium salt replacers are currently available, like Lo salt, Saxa So-low and Morton Lite Salt. Another example is Pansalt, a salt replacer that is reported to have almost half of the sodium replaced with KCl, magnesium sulphate and the amino acid L-lysine hydrochloride. This last ingredient is said to enhance the saltiness of the and mask the tastes from potassium and magnesium.
It should be noted though there are concerns with salt replacers for certain sections of the population, like people with type-1 diabetes, kidney problems, and heart failure, due to the increase in potassium load on the body.
The second approach to salt reduction is the flavour enhancers, such as yeast extracts, nucleotides, and monosodium glutamate. "Taste enhancers work by activating receptors in the mouth and throat, which helps compensate for the salt reduction," explained Desmond.
The third alternative for salt reduction is the optimisation of the physical form of the salt, making it more taste bioavailable and therefore reducing the amount of salt needed.
Research has looked at how crystal size and shape affect the perception of salt, including investigating flake salt or granular salt. The flake type has been reported to be more functional, in terms of protein solubilisation, binding and increasing pH.
"A number of companies, such as Morton Salt and Cargill Salt, manufacture various forms of salt and claim that they can be used at reduced levels and therefore there is potential to reduce the sodium content in products," said Desmond.
And only recently, as reported on FoodNavigator.com, Indian researchers announced that they had perfected a method of making round salt, producing a product that doesnt cake. It is not clear however if such round salt could be used in meat or baking products and the researchers have not performed any studies on differentiated taste.
"Research is continuing to look at various flavours, in particular more savoury/umani taste to enhance the flavour of reduced salt products," said Desmond.
But Desmond said that for the recommendations of salt reduction to be met there needed to be industry and government agencies working together, as we are seeing in some countries like the UK and Ireland. Re-education of consumers was also going to be a challenge.
"A reduced salt product which is left on the shelf or to which customers add salt at the table will not benefit anyone."
