The World Health Organization recommends that per capita daily salt consumption should not exceed five grams, but average intake is between 9 and 12 grams, increasing the threat of hypertension, a major risk factor for cardiovascular disease. Food manufacturers have been under pressure to reduce salt content in their formulations, as it is estimated that 60 to 80 per cent of salt consumption comes from packaged foods rather than salt added at the table. This raises challenges in terms of functionality – as salt plays an important role as a preservative or to control the fermentation of yeast – as well as consumer acceptability.
The new study, published in the May edition of the Journal of Food Science, looked at the way saltiness and acidity interact with each other in low concentrations.
Although previous studies have examined acids as a way to enhance saltiness, the researchers chose to focus on vinegar, which has a high concentration of acetic acid, because it is already used in cooking, whereas pure acids are not.
Salt substitution
The researchers used a panel of 35 to 40 young female students and established their individual detection thresholds for both salt and vinegar in distilled water solutions. When vinegar was added to a salt solution at half the concentration of the detection threshold of each panelist, they found that the threshold level of salt detection was ‘reduced significantly’.
“This result strongly endorses the usual practice to substitute part of salt with vinegar to give a satisfactory salty taste in dishes,” they wrote.
Amino acids
The study looked at the effect of both rice vinegar and rice black vinegar on perception of saltiness and found that rice black vinegar had a more pronounced effect, most likely “because rice black vinegar contains more amino acids, thus more nitrogen than rice vinegar.”
However, contrary to previous studies, the experiment did not reveal a reverse effect: When salt was added to vinegar at half the detection threshold, there was no change in panelists’ detection levels of either component. The researchers wrote: “This is very interesting since this breaks the symmetry of the enhancement/suppression between saltiness and acidity commonly believed.”
The researchers said they also hope that their findings might help in the hunt for the elusive salty taste receptor, which is yet to be discovered, even though taste receptors for sweet, umami, sour and bitterness have reportedly been detected.
Source: Journal of Food Science
Vol. 74, No. 4, 2009, pp. 147-153
“Saltiness and Acidity: Detection and Recognition Thresholds and Their Interaction Near the Threshold”
Authors: Keiko Hatae, Fujio Takeutchi, Mariko Sakamoto, Yasushi Ogasawara, and Hirofumi Akano.