Multiple emulsions may unlock sodium reduction options

Scientists from the University of Guelph and Ryerson University report that by formulating less stable emulsions alongside more stable emulsions could provide ‘pockets’ of saltiness in the mouth, while the overall sodium chloride levels of the emulsion is reduced.

“Our hypothesis was that ‘less stable’ emulsions would be perceived as saltier than ‘more stable’ emulsions, given that ‘less stable’ droplets would rupture and release their saline cargo upon oral processing when compared to ‘more stable’ droplets,”​ explained the researchers.

“As a result, more NaCl would be released near the oral mucosa, where the taste receptors and oral shear are most prevalent.”​

According to findings published in the Journal of Agricultural and Food Chemistry​, tests of their hypothesis showed that emulsions more prone to destabilization had a greater salt perception irrespective of their initial salt load.

“The knowledge gained from this study provides a powerful tool for the development of novel sodium-reduced liquid-processed foods,”​ wrote Matthew Rietberg, Dérick Rousseau, and Lisa Duizer.

Salt​

Salt is of course vital and is necessary for the body to function, but the average daily salt consumption in the western world, between 10 and 12g, vastly exceeds recommendations from WHO/FAO of 5 grams per day to control blood pressure levels and reduce hypertension prevalence and related health risks in populations.

And with 80 per cent of salt intake coming from processed foods, many countries have initiated salt reduction program, with many holding up the UK’s Food Standards Agency as the torch bearer for national initiatives.

The benefits of a salt global salt reduction strategy were given blinding clarity by a meta-analysis published in The Lancet Chronic Diseases Series​ in 2007, which concluded that reducing salt intake around the world by 15% could prevent almost nine million deaths between 2006 and 2015.

The topic remains controversial, however, with a prestigious Cochrane​ review concluding that salt reduction did not impact cardiovascular disease risk. However, this was subsequently slammed in a re-analysis of the same data in The Lancet, with the authors of this paper stating that salt reduction does provide a significant reduction in cardiovascular events.

Regardless of this ongoing debate, public health policy in many continues to advocate salt reduction, and the food industry continues to explore ways of reducing the salt content of its products without detrimentally affecting consumer liking.

Formulation​

The new study fits into that category. Rietberg, Rousseau, and Duizer prepared water-in-oil emulsions containing a saline-dispersed aqueous phase.

By varying the mass fraction aqueous phase (MFAP), salt level, and the concentration of surfactant concentration (polyglycerol polyricinoleate, PgPr of the emulsions they could influence the saltiness perception

The most important factor to correlate with saltiness was the emulsion MFAP, said the researchers.

“These findings have clear implications for the development of salt-reduced foods and highlight the delicate balance between ensuring adequate emulsion stability during the lifetime of a processed food and the requisite oral destabilization to ensure appropriate saltiness perception,”​ they said.

“If this balance is not found in a formulation, poor shelf stability and/or suboptimal salt taste perception will be the result.”​

Source: Journal of Agricultural and Food Chemistry​​
Published online ahead of print, doi: 10.1021/jf2051625
“Sensory Evaluation of Sodium Chloride-Containing Water-in-Oil Emulsions”​
Authors: M.R. Rietberg, D. Rousseau, L. Duizer