The world has a salt issue. Excessive salt intake is the leading cause of diet-related mortality globally, leading to nearly two million deaths each year, according to the World Health Organization (WHO).
While salt is essential in small amounts for vital bodily functions, such as nerve impulses and muscle movements, excessive dietary sodium is associated with increased blood pressure, which can lead to cardiovascular diseases and loss of bone density.
The WHO reports that the average daily sodium intake in adults stands at 4,310 mg per day, equivalent to 10.78 g of salt, which is more than twice the recommended limit of 2,000 mg of sodium (5 g of salt) per day.
Globally governments have committed to cutting national sodium intake by 30% between 2013 and 2025, but progress has been slow. To date, only a handful of nations have implemented robust sodium-reduction strategies, despite it being a key step towards meeting UN Sustainable Development Goal 3.4, which is to reduce deaths from noncommunicable diseases.
Cured meats
In some wealthy countries, such as the United States and Australia, pre-packaged foods account for more than 70% of the salt in diets. To help solve this issue, researchers at food manufacturer Kikkoman Corporation, headquartered in Noda, Japan, are striving to decrease sodium content in processed foods, while creating new low-sodium condiments for consumers.
Some of the processed foods with the highest sodium content are cured meats such as salami and bacon.
Salt not only amplifies the natural flavours of meat, but also interacts with other taste profiles unique to processed meats. Beyond taste, salt also plays an important role in the production of these products. It affects the solubility of essential proteins, influencing texture and moisture retention.
Salt also acts as a natural preservative. Through osmosis, it draws water out from both food and harmful microorganisms, preventing spoilage.
Takuya Sato in the Kikkoman Europe R&D Laboratory, based in Wageningen, the Netherlands, says the company’s researchers have been working with the University of Wisconsin-Madison in the United States to find ways of reducing sodium in cured meats.
One of their first joint studies was a project investigating whether replacing salt in frankfurters with soy sauce lowered sodium levels.1 In the experiment, they added salt or soy sauce during emulsification, a procedure for blending in the fat evenly across the meat. The results showed that substituting salt with soy sauce led to a 20% reduction in salt content without affecting the extent to which people found the frankfurters tasty.
In another study, published in 2018, the researchers found that combining fermented flavour enhancers, in this case a form of modified soy sauce, with potassium chloride, helped to reduce salt content by a further 35%, without compromising flavour. They then tested the combination in meats such as bacon and a dried beef product known as jerky, and found that certain quantities even led to a heightening of salt-like sensations among consumers.2
In addition to processed meat, Sato’s team succeeded in reducing sodium levels by 40% in bread by replacing salt with a fermented soy-based flavor enhancer.3 As bread and cured meat rank among the top 10 sources of sodium for adults in the US, “it was very meaningful to obtain significant results in these foods,” he says. In further work, Sato hopes to explore the effects in protein alternatives.
Individual choices
Meanwhile in Japan, condiments are a major source of sodium, contributing to nearly 70% of total intake. Even though soy sauce accounts for less than 20% of daily sodium intake, technologies to reduce sodium content in soy sauce are under discussion.
In 2020, Kikkoman began selling a line of soy sauce that achieved a 66% reduction in sodium. “This was a huge milestone that took a decade to achieve,” says Asahi Matsuyama, executive director of the R&D division at Kikkoman.
One of Kikkoman’s sodium reduction methods was inspired by extracting salt from seawater; they use an ion exchange membrane to extract salt from soy sauce brewed using regular methods. Using this technology, a more intense aroma and umami was achieved. New packaging technology also helped maintain the aroma for longer.
In Japan, one in two adults have high blood pressure, according to the Ministry of Health, Labour and Welfare. While many follow medical advice to cut down on flavouring or shift to low-sodium substitutes, alternatives need time to take off. “But consumers get used to the flavour of low-sodium product after a certain period of time, even though they find the alternatives less salty when they change,” notes Yasuharu Nakajima, managing director of the corporate planning division at Kikkoman.
He emphasizes that the company has looked for balance where consumers show similar preferences for regular and low-sodium soy sauces in blind taste tests. “Satisfaction with food choices is key to sustainable changes in diet,” he says.
“From an SDG perspective, food has a different role to play than medicine. Food should contribute by offering enjoyment for both people with and without dietary restrictions,” says Matsuyama.
Catering to diverse dietary needs
Kikkoman launched its first low-sodium soy sauce in 1965, when the University of Tokyo’s Department of Medicine requested the development of a condiment that retains the fragrance and umami of soy sauce, but with significantly less sodium for hospital settings. The product became available for regular shoppers in the 1970s.
Beyond its low-sodium offerings, the company also caters to other dietary needs. One of these is gluten-free soy sauce, which replaces soy and wheat with peas. Another is halal soy sauce, in which they modified the fermentation process to inhibit alcohol production.
In March 2023, Kikkoman introduced its first soy sauce alternative made from tomatoes for the United States market, which targets consumers seeking allergen-friendly condiments. Tomatoes are rich in glutamate, an umami compound that also gives soy sauce its savoury taste.
Asahi Matsuyama, an executive director at Kikkoman, adds that one of soy sauce’s advantages is that it’s already a complex product made mainly using the koji moulds, Aspergillus sojae and A. oryzae, along with a diverse range of microorganisms. “This brewing method uses the abilities of diverse bacteria to create something sophisticated and balanced,” he explains. “There’s tremendous room for creativity, be it in raw materials or combinations of microorganisms.”
For more information visit Kikkoman's website.
