A Pinch of Culinary Science

by Anu Inkeri Hopia

  17

  Can You Cut Down on the Salt Without Affecting the Taste?

  Consumer statistics and nutrition science tells us that we eat too much salt, 8–10 grams a day, twice the amount that we should. But what can you do? Salt tastes too good! In addition to being salty and, as such, very likeable, salt is a flavor enhancer on a deeper level than just the salty taste itself. In a research study published in Food Technology in 1985, Marianne Gillette described an experiment where respondents were to evaluate chickpea soups with various levels of salt. She found that the addition of only 0.3% salt, much lower than the usual content in such soups, resulted in the soup being experienced as more salty, sweeter, richer, more balanced, and with a larger overall flavor. The soup was also experienced to have less off-flavor, less metallic taste, and less bitterness. Compared to the same soup without salt, the panel even experienced the soup to have a thicker or richer texture! The first thing we can infer from Gillette’s paper is that various tastes affect each other when they’re experienced in the same mouthful. Based on a review article about such taste–taste interactions, Norwegian food blogger and chemist Martin Lersch made a figure that visualizes how tastes have been shown to affect each other (see figure).

  Taste–taste interactions

  ^The tastes enhance or suppress each other depending on concentration of the tastants. For instance, the figure shows that sweet taste at low and medium concentrations suppresses bitterness—and that this effect goes both ways. The figure is based on an illustration by Martin Lersch published in his blog khymos.org.

  These interactions are by no means simple or straightforward. As one example, salt in low concentrations may accentuate sweet taste, like when you add salt to sweet buns or the mentioned chickpea soup described by Gillette. Did your grandma advise you to add a pinch of salt in sweet dishes “to remove the watery taste?” But higher concentrations of salt can have the opposite effect and suppress the experience of sweetness. When it comes to bitterness, the sensation of salt seems to suppress the experience in both low and higher concentrations. Indeed, the word “salad” is said to have its origin from the word salt: the ancient Romans seasoned their occasionally bitter salad greens with salt, perhaps to suppress bitter taste. And salt promotes the pleasant taste of umami.

  Salt seems to have some magical powers over the sensory properties of food. If we need to cut down on the salt, do we simply have to accept that our food must be less tasty, a self-imposed asceticism where flavor is sacrificed on the altar of health? Or does there exist some sort of “hedonistic solution?” Perhaps knowledge about how we experience salt can be of help to maintain the good taste and, at the same time, reduce the intake of salt?

  Can we get used to less salt? Cutting down on salt is a bit like quitting smoking. Many have tried, and even succeeded, with the ascetic strategy. Others have tried and resigned, while others again don’t bother trying in the first place. In a dinner party, this situation could easily result in the person who has given up, or is indifferent to her or his salt intake, having to humbly ask the host to bring the salt to the table. Or, in fear of offending the host, accept that the food is experienced as somewhat bland. This everyday experience has support in science. In a doctoral thesis from 1988, Patricia Elmer showed that preference for salt subsided slowly when the research subjects cut down on the salt. Those who cut the salt by 30%, which is a rather radical change, preferred less salt after some time. But this change was slow: after three months the respondents had changed their preferences so that their perception of the “ideal” salt level was 15% lower than before the experiment. After half a year, it had reached a 20% reduction, and when the experiment ended after just over a year, the perceived ideal level was reduced by 25%. Conclusion: asceticism does work, at least to a certain extent.

  Does preference for salt vary between countries and cultures? There is research to support this notion. When researchers compared the recognition threshold among people from Myanmar and South Korea, they found that there was a considerable difference between the two groups. People in Myanmar, used to eating food rich in salt, had a higher threshold (0.17%) for recognizing salt taste whereas the South Koreans, with a traditionally low-salt diet, could recognize the salt in concentrations of 0.10%, which is the commonly reported minimum threshold for what is noticeable for humans. Indeed, the researchers link this, among other things, to the presence of refrigerators in the two countries, as salt is a preservative in non-refrigerated foods. Imagine what the threshold was 150 years ago, when preserving food by salt was a common practice (practically all meat and fish was highly salted) in many places?

  Furthermore, research shows that we use less total salt when we add it at the table compared to adding it during cooking. So even if the host who made the low-salt dinner put the salt shaker on the table, inviting the guests to add salt to taste, we’d probably come out with lower total salt consumption. A reason that this leads to less salt consumption might be that salt on the surface of the food is felt more intensely compared with salt dissolved in the water phase of the food. However, things are never as straightforward as they seem. Dissolved salt in, for instance, a stew will slightly change the properties of the water solution in such a way that aromas are more easily released, resulting in a dish with more intense, or less bland, flavor. For those versed in chemistry: aroma compounds are often rather nonpolar and volatile, and dissolving salt increases the water’s polarity and decreases water activity. This results in the water being less able to dissolve some aroma compounds, which are then more easily released, which we consequently experience as increased flavor. Finally, salt present during cooking may very well change the course of the cooking process. In one of our porridge cooking experiments we observed that adding salt before cooking led to a porridge where the milk became slightly curdled, whereas adding salt after cooking produced a porridge with a more homogeneous liquid part. Indeed, adding the salt after cooking gave a more preferable porridge. Also, salt makes a great difference when baking bread and cooking pasta, as it contributes to reinforce the gluten network (see Chapter 15 on cooking pasta).

  On British crisps. Those who have had potato chips in the United Kingdom, the Brits say “crisps,” may have noticed that some producers have printed “ready salted” on the plain salt versions. Why “ready salted” and not simply “salt” like, probably, the rest of the world would say? Yet another of those British oddities? Historically, the British crisps were packed unsalted, and you had to fish out the small packet of salt lying among the crisps and add the salt yourself before enjoying the snack. At some point, a producer got the idea that s/he could take the effort of adding the salt and use this in marketing the product. Thus, the British “ready salted” crisps were born. Do you think the crisp lovers among us would eat less salt if we were to add the salt ourselves? ×

  Reaching everybody. If the goal is to reach the whole population, the health authorities can probably not expect everybody to display the willpower that the ascetic strategy requires. Research has shown that pure health marketing reaches only a small part of consumers, whereas most of us simply turn our backs on purely health-marketed products. And if you are a restaurant chef, it is probably poor business to try to educate your guests by telling them that your food, albeit bland, is at least healthier. But perhaps we can use research-based knowledge and the taste–taste interaction diagram for our own and others’ benefit. If the figure is correct and representative for everyday use, it should be possible to add a small or medium amount of something sour, which should in turn enhance the experience of saltiness in the food. But balancing the amounts carefully is important, because, as the diagram shows, a high level of sourness may have the opposite effect. A home experiment could be to make identical batches of meatballs where both have less salt than given in the recipe but then adding a small amount of lemon juice or vinegar to one batch. Will the meatballs with lemon juice or vinegar taste saltier? If so, you may have found a way to reduce salt withou
t compromising on flavor.

  Furthermore, the figure implies that saltiness is promoted by umami in medium to high concentrations. Adding MSG (monosodium glutamate, common in many seasonings mixes) is obviously an alternative because it is one of the ultimate umami-tasting substances. However, MSG contains sodium, which is the component in salt we want to reduce. The relative amount of sodium is lower in MSG than in regular table salt, so there would be some limited benefit so long as you don’t use a comparably higher amount of MSG. An alternative that circumvents this problem is to team up with foods naturally rich in umami taste as listed in the info box.

  Smell can affect salt taste. The intensity of salty taste can also be enhanced by some smells. Sometimes you may get the notion that something smells sweet. This sounds a bit odd as sweet is a taste happening on the tongue and not in the nose, and sugar has basically no smell in and of itself. As described in an earlier chapter, we make connections across the senses. This type of dialogue between the senses is the result of experiences accumulated in life. Strawberry jam is sweet and thus the smell of strawberry jam could lead to thoughts of sweetness. A very convincing research study carried out by the French researcher Thierry Thomas-Danguin and coworkers showed that respondents experienced tasting water with a small amount of sardine aroma to taste slightly salty compared with plain water, even though neither water samples contained any salt whatsoever. And the panel experienced that water with a small amount of salt tasted saltier when a small amount of sardine aroma had been added. Some health promoters and health authorities suggest adding herbs and spices to compensate for reduced salt, but it is difficult to find solid support for this in published research. We would think that researchers in the future will find links between taste and smell, as shown in the sardine aroma experiment, to also include certain herbs and spices as salt-enhancing. But, on the other hand, why wait for the researchers when we can play with these combinations today in our own homes?

  Umami-rich foods. Some foods are naturally rich in umami taste, which could also boost the experience of salty taste. Some of these contain salt, but they might still contribute to a reduction in the total intake of salt:

  – Chinese cabbage, especially as fermented kimchi

  – Fermented soy products, soy sauce

  – Hard and stored cheeses, such as parmesan

  – Green tea

  – Meat, especially dried-cured ham

  – Mushrooms, especially dried shiitake

  – Potatoes

  – Seafood, like fish sauce, anchovies, sardines, salted squid, clams, mussels, and oysters

  – Seaweed, especially Japanese kombu

  – Tomatoes, especially ripe or dried tomatoes ×

  Trusting industry? Even though taste–taste and taste–smell interactions may be effective, it can be difficult to make use of them in everyday cooking because the effects may rely on tweaking very fine balances to make it work. Historically, a large part of the excess salt we ate came from industrially prepared foods and not from the meals we cooked from scratch at home. In many cases, this is still the case. In fact, according to the Norwegian health authorities (2016), a way to reduce your salt intake would be to prepare the food yourself, from scratch. However, salt from industrially prepared food is not only about TV dinners, freeze-dried soups and stews, frozen pizzas, and so forth. It is just as much about the things you put on your homemade packed lunch: pâtés, cheeses and sandwich ham. So, regardless of whether you buy your lunch at a café or you bring your own sandwich, you may have a high-salt meal. If the salt-reduction project requires that the population starts making their own cheese spreads, hams and pâtés, we are probably more in the realm of fairytales than realities. Then it would be much easier to make the industry reduce the salt content in their food, and indeed many manufacturers work seriously on this. Health authorities worldwide have for some time put pressure on the food industry to decrease salt levels. Although this approach is not straightforward, promising initiatives exist. For instance, in 1975, the health authorities and the industry in Finland agreed to reduce salt content in industrially prepared foods, and by 2002 the salt intake had decreased on average by three grams per day. Similar results have been seen, for example, in the United Kingdom. In the United States, the Food and Drug Administration have developed targets for American food manufacturers, in the European Union, a “Salt campaign” has been initiated, and the World Health Organization has its salt reduction program targeting both industry and the population in general. Still, the industry and professional food services have to make the food taste good—otherwise consumers won’t buy their products. A fine balance indeed. Luckily, many of the larger manufacturers have research and development divisions that spend resources on developing low-sodium recipes. And if you can claim “less salt, the same great flavor,” you may contribute to the customer’s health while also being a successful food manufacturer. But while people in some countries usually bring their cold, packed sandwich lunches from home, people in other countries have their hot lunches prepared and served by professional kitchens. Thus, salt-reduction strategies also need to align with the eating habits and food culture of the population.

  However, it would be rather defensive of us to sit passively and expect that the food manufacturers should solve this whole issue for us. Building on knowledge about taste, smell and connections between senses (multisensory correspondences), we may start making a difference in our own kitchens as well by:

  – Experimenting with flavor combinations that could enhance salty taste: use a small amount of something sour, or try adding an umami-rich ingredient.

  – Instead of adding salt, use ingredients with aromas that are often associated with salty taste, such as sardine/anchovies, low sodium soy sauce, and fish sauce.

  – Use less salt when cooking and add salt at the table. However, this will give a different taste perception than a ready salted and balanced dish.

  – When enjoying salt-rich food, such as a pizza, use side dishes with little or no salt such as a fresh salad. This would give a lower average salt concentration in the meal as a whole.

  – Reflecting on the flavors we experience while enjoying food; it isn’t snobbish to talk about what you’re experiencing while eating even though some would claim otherwise.

  The salt experiment. We wanted to test if some of the research-based knowledge on taste–taste interactions and taste–smell interactions could be made to work in our own kitchens. Is it possible to reduce the amount of salt and compensate with some other taste or smell? We went ahead to design an experiment that tested if adding small amounts of sour taste, umami taste, or herb aroma would make a dish taste saltier. We did two parallel experiments: one with beef bouillon and the other with fish bouillon. This way, we were able to test this in two foods that were very similar but with different flavor profiles. In both cases we made a base bouillon without salt, divided it into four parallels and added different combinations of flavor ingredients. The participants were to blind taste the samples and rank them in order of least salty to most salty. The salt level was identical in the four, near the threshold of being noticeable as having salty taste. If any of the other ingredients did actually affect the experience of saltiness, these samples should taste saltier than the one with only salt. The four parallels contained: a very small amount of MSG (parallel A), a little herb that would impart a mild aroma commonly associated with salty dishes at the same time imparting little or no taste on the tongue (parallel B), only salt for comparison (parallel C), and a very small amount of vinegar (parallel D).

  Bouillons for blind tasting A

  0.3% salt + MSG (umami taste); total Na+ is identical to the other samples

  B

  0.4% salt + herb commonly associated with salty taste (beef bouillon: parsley, fish bouillon: lovage)

  C

  0.4% salt

  D

  0.4% salt + 0.05% vinegar (sour)

  ^Four different beef bouillons and fou
r different fish bouillons were prepared, each with different salty-taste-enhancing ingredients, to study how the added (non-salt) ingredient affected the perception of salty taste.

  The effect of tastants and aroma on salty taste

  ^The samples with a mild herb aroma and sour taste were perceived as saltier in the beef stock, while the result was the opposite in fish stock.

  The results are shown in the diagram. The participants tasting the beef bouillon were quite clear about the herb-and vinegar (sour) parallels being saltier than the other two: saltiness and savory aroma seemed to increase the perception of saltiness. However, the parallel experiment done with fish bouillon gave the exact opposite result. The effect may perhaps be product/context dependent. Is this effect real and, if so, how come? Could it be that the flavors of meat and fish bouillon respond differently to the added ingredients? This is not unlikely as bouillons are complex mixtures of many chemical substances that produce a complex range of flavors. The proper research experiments showing such taste–taste interactions are often carried out in very carefully controlled environments, sometimes with basic water solutions with minimal amounts of other ingredients added. In our, more relaxed and naturalistic context, subtle differences are not that easy to pick out. Maybe this is the explanation why we did experience a difference in the mild beef bouillon, but not in the fish bouillon, which often has a more prominent flavor.

  Anyhow, the beef bouillon experiment tells us that there might be validity to such salt-reduction strategies, but the fish bouillon experiment shows us that they are not necessarily straightforward to apply. It certainly shows us that the world of everyday life is complex and not easily reduced to controlled lab experiments. On the other hand, it is one of the simplest of things to experiment with flavors if the only thing you need to do is to add a few drops of vinegar or some leaves of an herb to make an experiment. As long as we stay curious and continue experimenting at home and in labs, these formal and informal inquiries could maybe, in themselves, help us cut down on salt. At least, they will give us many nice experiences.