Tasting Salt Part 4: Salt and the Food Industry

The food industry loves salt, it is a magic ingredient with the ability to change an unpalatable food to one that is flavoursome and appealing. As Heston Blumenthal stated, it is the most important ingredient in the kitchen.

Bread

Let’s take bread as a food that uses the multiple functions of salt.  Bread produced without salt has a vastly different taste to bread produced with salt – not only taste, but the texture is different, and 99.99% of consumers prefer their bread produced with salt.  It may seem hard to believe, but bread is the single largest source of salt in our diet; yet bread is not salty like potato chips are salty.  That is because the majority of salt is bound within the matrix and unavailable to activate our taste receptors.  It is within the bread matrix that salt has some functions, salt controls growth of yeast and promotes the development of gluten structure/texture in bread, as well as adding or enhancing flavour.  As a cook, baker or food manufacturer you would be crazy not to use salt.  The reason for salts continued (increased in the case of Australia, if you trust the recent data from Australian division World Action on Salt and Health (AWASH)) use in processed foods, given the multiple health reasons not too, is the multiple positive functions salt has in the food matrix.

Take meat and cheese products as examples, both are high in salt and if a manufacturer was making a reformulated meat product (chicken patties or similar), reducing the salt would adversely affect texture and require other additives to replace the water-holding, protein-binding, and fat-binding functions of the salt. In cheese, additional additives would be needed to help promote good bacteria and inhibit bad bacteria during fermentation and aging.   But what are the compounds that can replace the function of salt, and what is the cost, consumers may not be able to afford or willing to pay for a significant increase in the cost of salt reduced foods.  In addition, we must not forget the role salt plays in preservation, as it reduces water activity in foods and acts to control growth of pathogens and spoilage organism.  If salt levels are decreased, it will be necessary to use other preservatives to ensure safe foods with a reasonable shelf life.

From a food industry perspective, in addition to processing and safety challenges involved in producing low sodium foods, there is also an economic consideration. If it becomes apparent to a food manufacturer that consumers prefer a higher concentration of salt over the current concentration, salt may be added to that food at very little cost.  For example, the approximate price of salt is 34 cents/ kg, if food manufacturers wish to increase the salt concentration of bread by 5% the approximate cost would only be 0.000756 cents/100 g. Salt is very cheap and any substitute used will increase the cost of the product. Production of foods with reduced salt will require reformulation and additional associated costs of consumer testing and pilot plant tests.  Are we as consumers willing to pay the extra costs associated with reduced salt products, or are we willing to accept inferior products? Possibly not.  Are we willing to accept myriad new additives that will be needed to replace the functions of salt? Again, possibly not. While the flavour aspects of salt are undoubtedly the main reason why salt is in foods at the level it is, there are also technical reasons to maintain salt levels in foods

It is widely accepted we have a food supply that delivers too much salt for population health.  How to fix the problem is the issue.  The most effective strategy is to reduce the level of salt in manufactured foods, as they deliver 75% of dietary salt.  The food industry correctly states salt reduction is not easy to do, and there are costs involved. And we as consumers are likely unwilling to accept increased costs that will be involved with salt reduction.

One thing for certain, the last thing we need is food manufacturers increasing the current levels of salt in foods, as AWASH reported recently.  There is no need for more salt in bread, or increased levels in cereals. If voluntary food industry targets cannot be determined or met for specific foods, the next step should be to legislate maximum levels of salt in foods.  Perhaps this is needed, if so, start with bread at a maximum level of 800mg NaCl/100g bread – this is a good compromise value, the functionality the bread matrix is maintained, taste is fine and will be a significant step forward in reducing population salt intake.

As (hopefully) explained over the past 4 blogs, salt is a problem with no easy answer.

 

Also seen on Russell Keast’s blog http://russellkeast.blogspot.com.au/

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Tasting Salt, Part 3: Health

NaCl is an easy additive for the cook to use, as it is a cheap and convenient way to increase liking; therefore from a cooks perspective it is like magic powder, add NaCl to a food and the food becomes more palatable.  To health advocates NaCl is a slow working poison, added to foods in excess, slowly killing the population via myriad disease conditions.

Eating-less-salt-m

If salt is a poison then why are we allowed to use it as a food ingredient?  The answer lies in the rate we consume NaCl, and if you over-consume there are consequences (to help with quantities mentioned in this article, 5g NaCl is equivalent to 1 teaspoon).  It is calculated that human species evolved with intakes of 1.8g NaCl/day, in comparison we now consume >9g NaCl/day, with approximately 75% of intake coming from processed foods.  As a result there has been a 400% increase in NaCl consumption during recent human history.  The excess consumption of NaCl is the source of the problem identified by health advocates who have suggested an adequate intake of between 1.2-2.3 g NaCl, and an upper limit of approximately 6 g NaCl for chronic disease prevention.  It is important to note that it is the Na or sodium portion of NaCl that is implicated in the adverse health effects, but for simplicity, I will continue to use NaCl.

Evidence that excessive NaCl intake has an adverse effect on blood pressure regulation is well established, as is the relationship between raised blood pressure and cardiovascular disease.  In a confusing twist, the link between NaCl intake and cardiovascular disease is more tenuous, but we presume that chronic excessive NaCl intake increases blood pressure, which in turn increases incidence of vascular diseases. It is reported that approximately 30% of Australians are diagnosed with high blood pressure (hypertension) and for every known case of high blood pressure it is believed that there is one case that goes undiagnosed.

Excessive NaCl consumption is a big problem, to illustrate the effect excessive NaCl consumption has on public health, consider this; a 3g/day reduction in dietary NaCl would have the same effect on rates of heart disease as a 50% reduction in tobacco use, and a 5% reduction in body-mass index among obese adults.  Also, a 5 g/day increase in dietary NaCl is calculated to increase the risk of stroke by 13-32% and heart disease by 50-61%, with the higher risk associated with overweight/obese individuals.  Excessive NaCl intake has also been linked to gastric cancer via enhancing H.Pylori colonisation, and decreased bone density by increasing calcium loss from bones.  There have also been suggestions of a link between NaCl intake and obesity with an increase in dietary NaCl inducing thirst resulting in an increase of the amount of high kilojoule drinks consumed, consequently leading to excess energy intake.  The potential health benefits from reducing sodium are staggering and hard to believe more is not done to reduce NaCl levels in the food supply. But…. there is, of course, conflicting data and an investigation of NaCl intake over the past 50 years suggests NaCl intake has been stable.  Yet rates of cardiovascular disease have declined over the same period. Such inconsistency do not mean excess NaCl intake is harmless, it just means there are other factors involved in vascular diseases that have influenced disease rates.

NaCl intake seems a little like Russian Roulette, there is a chance that the bullet (NaCl) may not be in the chamber, but is it worth the risk when the only benefit appears to be better tasting food?  Perhaps the only effective way to have population based reduction in salt intake is government regulation, targeted to the foods that contribute most to salt intake – bread, processed meats.  That way all food manufacturers must adhere and no one manufacturer will have a competitive advantage by adding more salt.  This will strike stern opposition from food manufactures because……. That is for Part 4.

 

Also seen on Russell Keast’s blog http://russellkeast.blogspot.com.au/

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Tasting Salt, Part 2: Flavour

Why is NaCl, according to some cooks, the most important ingredient when cooking?  The reason is simple, added NaCl has a positive influence on liking and preference for foods.  And it is not just due to saltiness, although saltiness is one component. Apart from savoury foods where it appears naturally complementary, it is also added to caramel, chocolate and foods we associate with another taste, sweet.  Perhaps it is the subtleness of small amounts of salt in sweet foods we like, maybe the sharp contrast when you taste a some NaCl in a sweet food, or maybe it is something else.

When two compounds with different taste qualities are mixed a number of interactions may occur including suppression of bitterness by NaCl. NaCl also enhances sweetness at low concentrations, and through NaCl effect on bitterness, sweetness maybe further enhanced.  NaCl also has the ability to enhance aromas associated with sweetness (we like them) and suppress aromas associated with bitterness (we don’t like them).  In this situation, adding NaCl to a food has created saltiness, increased sweetness and sweetness associated aromas, all aspects of food that we like.  NaCl has also decreased bitterness and bitterness associated aromas, thereby reducing the negative aspects of food and also increasing our liking of food.  You start to appreciate the wisdom of Heston Blumenthal’s statement – but there is even more. NaCl also acts as a preservative and water binding agent in processed meats and influences on the texture of foods such as breads.

When you have one compound with so many positive influences on the flavour of food, and is cheap, convenient to use, and not acutely toxic, all this adds weight to being the cooks most useful ingredient.  In a way I agree with Heston Blumenthal, NaCl is the most useful ingredient for the cook, just as the hammer is the most useful tool for the builder.  Using an analogy, a builder (or handy person) faces a problem, the hammer is close by, the hammer becomes the solution; it is low tech, easy to use and it may work. The same happens with NaCl in the kitchen, perhaps it becomes the ingredient that is the solution to everything, it is at hand and easy to add some NaCl to every dish, at every stage of production. The accumulation of NaCl in a food adds up and there begins another problem. Much of the added sodium is trapped within the food matrix and unavailable to fulfill its role in taste, it becomes taste invisible (this will come up in Part 4 of salt).  Yet when the food is swallowed and the food matrix broken down, the NaCl is adsorbed and available for physiological function.

After consideration and remembering the old nutrition mantra, ‘everything in moderation’, I would qualify the Blumenthal statement that ‘salt is the most important ingredient for the cook’, by saying NaCl is the easiest ingredient a cook can use to increase liking of a dish. It is a process similar to delayed gratification, using excessive NaCl in the dish you are preparing may (not will) increase the liking of the dish, but the excess sodium may also cause detrimental health effects in a few years.  The evidence that we consume excessive sodium which is associated with many detrimental health effects.  That is for Part 3.

Overall, reducing sodium in foods has more influence than merely reducing saltiness and the interactions that occur may be complex. There are many gaps in our knowledge of taste interactions and this lack of base knowledge is a major constraint in developing successful strategies to modify sodium consumption.

 

Also seen on Russell Keast’s blog http://russellkeast.blogspot.com.au/

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Tasting Salt, Part 1

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The story of salt will be in multiple parts, due to the importance of the topic, and the complexity.  Salt, a.k.a sodium chloride, a.k.a. NaCl, a.k.a. sodium, is an essential element in the chefs or cooks toolbox to make things taste good. I read somewhere that Heston Blumenthal (one of the high priests of cooking, TV personality) stated salt is the most important ingredient in his kitchen. Why would that be the case? Below I begin the discussion on the many functions that salt has in foods, hopefully giving a clue to why such statements are made. Part 1 does not address the health issues and controversies around salt, just why we, as consumers and cooks, love salt. Also an explanation on terminology, I will use the term salty when referring to the taste we perceive, and NaCl when discussing salt (opps NaCl).

Taste perception is very complex, with highly sophisticated biological systems at work, but it can also be quite simple, put something in your mouth and you experience the taste/flavor of the food.  Salt taste is experienced when the concentration of NaCl in the oral cavity reaches a level that not only activates a taste receptor, but the signal sent from the receptor is strong enough to elicit a salty perception, meaning low concentrations of NaCl may be present in the oral cavity yet not elicit a salty taste.  There are multiple perceptual phases associated with salt taste perception and as the concentration of NaCl increases the detection threshold will be reached, the level at which NaCl in solution may be discriminated from water.  As the concentration of NaCl increases further the recognition threshold is reached, the point at which the quality (e.g., salty) can be identified.  As the concentration of NaCl increases still further, the intensity of saltiness mutually increases to a strongest salty intensity we can experience.  It then starts to activate another sensory system (not taste) and becomes painful.

Two factors dictate the level of perceived saltiness for a given concentration of NaCl: 1/ an individual’s sensitivity to NaCl (which is highly variable for all tastes), and 2/ the food matrix being consumed. To further explain: 1/ just because you find something too salty does not mean I will, as we have variation in the biology or physiology relating to taste processing.  And 2/, the food matrix will be important, potato chips are a salty food, they have NaCl at the surface of the chip, bread is not a salty food, yet it contains about the same amount of NaCl.  The reason for the difference is that the NaCl in bread is trapped in the bread matrix and unavailable for taste activation.  Therefore a salty food such as potato chips are not necessarily a food high in NaCl.

NaCl adds saltiness to foods, depending on the amount you add, the food matrix and individual taste will depend on the level of saltiness you experience, e.g., 50 mM NaCl in liquid is saltier than 50 mM NaCl in solid food. This doesn’t adequately explain why NaCl is the most important ingredient in Blumenthal’s toolbox.   That can wait till Part 2.

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Figure 1:  (Keast et al. 2004)

It is not only perceived saltiness and concentration of NaCl we investigate in this study, but also an individual’s hedonic response to NaCl in foods. Hedonic responses to NaCl in foods will follow and inverted U shape in response to increasing intensity (and concentration) with an initial increase in liking as the perceived intensity increases until an optimum liking  or “bliss point” is reached (Figure 1) (McBride 1990).

Environmental factors are believed to play a major role influencing an individual’s sensitivity, liking and consumption of salty foods (Keskitalo et al. 2008; Mattes 1997; Wise et al. 2007).  Sodium reduced diets have been shown to increase an individual’s NaCl taste sensitivity in foods and subsequently decrease liking of higher concentrations of NaCl in various foods (Bertino et al. 1982; Blais et al. 1986). However, no association was found between usual dietary sodium intake and NaCl taste sensitivity (Pangborn and Pecore 1982) bringing into question the relevance of NaCl taste sensitivity to dietary intake. Actual sodium intake may have little relation with perceived saltiness due to various taste interactions or structural effects in foods that modify the perceived salty taste elicited by NaCl.

References:

Bertino, M., Beauchamp, G., Engelman, K. (1982). Long-term reduction in dietary sodium alters the taste of salt. The American Journal of Clinical Nutrition, 36, 1134-1144.

Blais, C., Pangborn, R., Borhani, N., Ferrell, F., Prineas, R., Laing, B. (1986). Effect of dietary sodium restriction on taste responses to sodium chloride: A longitudinal study. The American Journal of Clinical Nutrition, 44, 232-243.

Keast, R. S. J., Dalton, P., & Breslin, P. A. S. (2004). Flavour interactions at the sensory level. In A. Taylor (Ed.), Flavour Perception (pp. 228-255): Blackwell Publishing

Keskitalo, K. (2008). A matter of taste: Genetic and environmental influences on responses to sweetness. National Public Health Institute, Finland, Academic Dissertation.

Mattes, R. (1997). The taste for salt in humans. The American Journal of Clinical Nutrition, 65(2), 6925-6975.

McBride, R. L., & Finlay, D. (1990). Perceptual integration of tertiary taste mixtures. Perception and Psychophysics, 48, 326-330

Pangborn, R., Pecore, S. (1982). Taste perception of sodium chloride in relation to dietary intake of salt. The American Journal of Clinical Nutrition, 35(3), 510-520.

Wise, P., Hansen, J., Reed, D., Breslin, P. (2007). Twin study of the heritability of recognition thresholds for sour and salty taste. Chemical Senses, 32(8)

 

Also seen on Russell Keast’s blog http://russellkeast.blogspot.com.au/

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The Deakin University Sensory Lab

The Deakin Sensory lab is located at the Melbourne campus of Deakin University, Australia. We are housed in the School of Exercise and Nutrition Sciences, within the Faculty of Health and consist of a team of researchers and students (PhD, Masters and Honours students) who are investigating various aspects of taste, flavour and acceptance of foods.  We have state-on-the-art facilities for undertaking sensory research, descriptive analysis and consumer testing.  Topics currently under investigation within the lab include bitter taste in foods, fat taste sensitivity, sweet and carbohydrate taste, irritation of oleocanthal (found in olive oil), compounds in strawberries that drive liking, and food compounds that stimulate satiety. For further information, please follow us on Twitter (@DeakinSensory) and see our website at http://www.deakin.edu.au/health/ens/.

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