The study, published in the Journal of Sensory Studies, explored the use of soy sauce to reduce salt intake in daily food preparation by replacing all or some added salt with naturally brewed soy sauce – without producing changes in consumer acceptance.
The researchers, from the National University of Singapore and soy sauce manufacturer Kikkoman, replaced added salt with natural soy in three model foods: salad dressing, tomato soup and stir-fried pork – finding in consumer acceptance tests that replacements between 33 and 50% were acceptable to the consumer whilst reducing levels of salt.
“It was possible to use soy sauce to reduce added salt by 33–50% as the amount of NaCl in soy variant is lower than the salt variant for the same pleasantness,” said the researchers, led by Lai Peng Leong of the National University of Singapore.
“The method can be used by food industries to produce reduced salt products or by consumers at home,” they added, noting that the percentage of salt reduction achievable may be higher in populations with regular prior exposure to soy sauce in their diet.
Leong and his colleagues noted that the relationship between the high salt consumption and hypertension has led to dietary recommendations to reduce salt in foods globally – with pressure from governments, charities, and consumer action groups for manufacturers to reduce salt levels in foods.
However, salt reduction in processed foods is often difficult to achieve due to the technical challenged associated with removing salt, and the reduction in acceptability of many reduced-salt foods.
The research team noted that many flavour enhancers, especially umami flavours, which are able to enhance the saltiness of food when used together with salt, have been shown to reduce the amount of salt needed in certain foods.
“The aim of this study was to determine whether it was possible to use soy sauce to replace sodium chloride in some foods consumed in Singapore without decreasing consumer acceptance of these foods,” said Leong and his team.
The research team replaced added salt with naturally brewed soy sauce (Kikkoman Food Europe B.V.) in the three model food systems. The authors stated that all other ingredients were ‘held constant’ during the research, “except for the quantity of salt and soy sauce added into the foods.”
Leong and his co-workers reported no significant loss in the pleasantness –“which is the most important factor when it comes to consumers' acceptability” – when soy was replaced for salt in any of the products at levels between 33 and 50%.
In the case of stir-fried pork, the pleasantness is increased in the presence of soy sauce, they noted.
“This article shows that it is possible to reduce salt in foods without compromising the taste intensity and pleasantness of the food by replacing salt with naturally-brewed soy sauce,” said the researchers.
Source: Journal of Sensory Studies
Published online ahead of print, doi: 10.1111/j.1745-459X.2011.00357.x
“Using naturally brewed soy sauce to reduce salt in selected foods”
Authors: F.W. Goh, Y. Itohiya, R. Shimojo, T. Sato, K. Hasegawa, L.P. Leong