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A Novel Salt Substitute: Smell

A few months ago I reported on a study done in The Netherlands that looked at the flavor effects of reducing sodium in bread. In addition to simply reducing the amount of salt in a slice of bread, they also tried using a salt replacement in the bread to see if that would be more acceptable to their study participants. The salt replacement they used is by far the most popular salt replacement: potassium chloride. The problem with potassium chloride, however, is that you can only use so much of it in a product before it starts to give that product a bitter, metallic flavor.

Researchers with Unilever, one of the world's largest food companies, have been looking at different ways they might reduce the sodium content in foods without compromising flavor. The flavor effects of reducing sodium in a food, they noted, isn't limited to reducing the food's perceived saltiness: it also affects other components of flavor as well as reducing the food's overall flavor intensity. Would other ways of boosting flavor help compensate for lower sodium?

As flavor researchers they were aware that the sense of smell has a strong interaction with and influence on the sense of taste. (Just try eating with your nose plugged and you'll see how strong that influence can be.) In fact, research has been done that shows that cheese tastes less salty if the taster uses nose clips during tasting.

They decided to test aroma enhancements on chicken and beef broth - both of which depend quite a bit on the salt they contain for fullest flavor (J Food Sci doi: 10.1111/j.1750-3841.2011.02198.x). Ten men and women tasted each of the following broths and rated them on salt intensity and overall intensity of flavor:

• Regular, full-sodium-level broth;
• Broth with 30% less sodium;
• Broth with 30% less sodium and added beef or chicken flavor (and therefore scent); and
• Broth with 30% less sodium, added beef or chicken flavor, and potassium chloride as a salt replacement

They found that the broth with less sodium and added flavoring was perceived to be almost as salty as the original, while the broth with less sodium, added flavoring and the salt replacement was considered to be almost indistinguishable from the original.

To go even further, the researchers gave the chicken broth to a trained panel of tasters - people who are able to discern the smallest differences in flavor and use a standardized set of terms to describe the flavors accurately. The tasters agreed that the reduced-sodium chicken broth was less "salty" and "umami" and had a lower "fullness" of flavor than the original, full-sodium broth - as you might expect, since salt is used as a flavor enhancer.

Adding only the salt replacement to the reduced-sodium chicken broth did not restore the "salty," "umami," and "fullness" scores and added a noticeable metallic flavor (remember, these are trained tasters). However, adding the extra chicken flavoring to a slightly lower level of salt replacement meant that the panel could only perceive a difference between it and the full-sodium original when they directly compared the two.

What this means for you

This is proof that sodium can be reduced without compromising flavor. It's encouraging to know that companies like Unilever are pursuing this kind of research. Many companies, such as Lean Cuisine, are already doing this by using potassium chloride in place of some of the sodium in their food. I look forward to other companies doing the same.

First posted: July 25, 2012