Salt Reduction? … don’t forget fermentation!

For some people, taking salt out of their favourite foods is like taking the joy away from taste and flavour. For others, salt reduction has proved to be one of the toughest challenges faced by the food industry in recent years. Each new set of tougher salt targets generate ever decreasing circles for manufacturers to work in; making it harder to not compromise shelf life and taste. Some food categories are fast approaching the nite limits of how much salt can be taken out whilst retaining palatability. It is widely known that elevated sodium levels can lead to hypertension and potassium chloride salt substitutes can negatively impact people suffering from kidney problems. However, the fact remains that both sodium and potassium are essential minerals for basic bodily function and cannot be excluded from a balanced diet. Therefore, where further salt reduction is not feasible, should the industry consider an alternative approach based on achieving optimum balance between sodium and potassium intake?

To retain acceptable shelf life in salt reduced foods, one may need to find ingredients that naturally enhance flavour whilst performing the “solute” function of salt to compete for “free” water and thus restrict micro-organism growth and spoilage. Currently, it is common to see savoury recipes use ingredients with naturally occurring glutamates to give a clean label flavour enhancement. These can range from the relatively expensive “trendy” ingredients like seaweed to a tried and tested yeast extract you would find in any kitchen cupboard. Curiously enough, traditional processing methods with the ability to deliver natural flavour enhancement have recently come back into vogue. One such example of this is the natural fermentation of sugars into acids using yeast or bacteria.

The products of fermentation have a wide application from controlling acidity for shelf life to naturally enhance savoury flavours as well as improving nutrition and digestion. The calcium lactate facilitates lactic acid to penetrate into bacterial cells un-dissociated to give an anti-microbial effect. Firstly, once inside the cell the lactic acid dissociates to lower the bacterial cell pH and in turn the cell uses more energy to counteract this effect. Secondly, the lactate also disrupts the glycolytic pathway that generates energy for bacterial cells. The net result of both interactions is to slow bacterial cell growth and multiplication.

The goal of any fermentation process is simple; make sure there are more friendly bacteria than harmful bacteria at the end of the process to achieve the desired product intrinsic parameters and organoleptic profile. The probiotic benefits arise primarily from the promotion of lactic acid production from friendly lactobacilli during fermentation which helps to preserve the vitamin & enzyme content of the food, increase nutrient bio-availability and give better conditions for digestion. Fermentation is a process that does not always rely on added salt to work but getting levels right is important. Adding too much slows the rate of fermentation but adding enough can help to draw out moisture and promote a crispier texture in foods like vegetables.

At this point, a clear distinction needs to be made between fermented and pickled foods as they do not always yield the same result. For example, the pickling of vegetables requires an acidic medium (such as vinegar or combinations of organic acids) to control pH and thus give a preservation effect. However, if you were to take the same vegetables and ferment them using a starter culture and salt, your finished product would yield more enzymatic and probiotic bene ts not possible with pickling. By contrast, the lower pH of pickled foods ends up disrupting the digestive process, making it harder for gastric juices to break down food. For a vegetable pickled in vinegar, only the vinegar is fermented (not the vegetable) and therefore you get a finished product that has a different taste and texture to a fermented vegetable.

Kimchi is a Korean vegetable dish that relies on the fermentation by-products of lactic acid bacteria to promote probiotic qualities such as good retention of mineral content. However, the addition of salt to this recipe has always prompted concerns in a country where the average daily sodium intake is amongst the highest levels worldwide (5000 mg/day). Therefore, between 2007 and 2012, the Korea National Health & Nutrition Examination Survey collated data regarding kimchi consumption and its effect on sodium intake levels. The study concluded that high consumption of kimchi was not directly associated with a prevalence of hypertension. They believe this was due to high potassium intake from vegetables within kimchi neutralizing the effect of elevated sodium intake on blood pressure levels. Therefore, this was an example where the fermentation process allowed the vegetable to retain good potassium content and this counteracted the effect of added sodium (from salt) in the recipe.

A Harvard Medical School paper from 2009 outlined the key reasons for sodium and potassium balance. Kidneys help to regulate mineral balance by flushing out excess sodium via urine but this also has the effect of removing potassium. If potassium levels are low, the body tries to hang on to both it and sodium; this leads to the osmotic imbalance that eventually increases blood pressure and forces the heart to work harder to achieve adequate circulation. Too much sodium stops blood vessels from relaxing and contracting easily plus it can also over-stimulate growth of heart tissue; all of these responses are exacerbated with low potassium intake. Therefore, the study in this paper suggests that decreasing sodium and increasing potassium needs to be done simultaneously (not in isolation) to combat hypertension and heart disease.

Hence, the sodium-potassium balance approach is something people need to start considering when looking at salt levels within diets; simple reduction is not always the answer for every food category. Fermented foods like sauerkraut, kombucha and beverages like kefir are very much publicised for giving health benefits owing to the variety of friendly microbes present to improve the human gut microflora. Currently, there is an open source crowd funded project called “British Gut” whose aim is to identify the composition of gut micro ora of people in the UK. It is hoped this information will help to identify ways of improving gut microbiome and thus reduce health related problems linked to poor diets. So, the next time you consider options for salt reduction, remember to trust your “gut instinct!”

Sources

By Tayab Haq,
Brenntag UK & Ireland

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