In Asia it is not uncommon to eat fruit with salt or even soy sauce. From my own experience, and via friends, I known that fruits such as mango, guava, honey dew melon, watermelon, nashi pears and papaya are eaten with salt. Interestingly salt is used both for ripe and unripe fruit – the latter is especially the case for mango and guava. With unripe fruit I can imagine that the primary motivation is reduction of bitterness. I’ve previously blogged about salt and coffee and how salt in tonic water reduces bitterness – the mechanisms are the same. In addition to the bitterness suppression low concentrations of salt will enhance sweet taste. [1] This would certainly be an advantage in unripe fruit. In ripe fruit there is hardly any bitterness left (or at least I presume that is the case), so here the salt may serve a different funtion. Could it be to balance the sweet taste and give a more savory and complex flavor? Perhaps it could also be explained as increased sensing by contrast amplification?


Nashi pears (Asian pears) are delicious when served in a bowl of salty water!

One particular combination of fruit and salt that I remember from growing up in Taiwan is eating slightly unripe guavas with a beige powder. We would either sprinkle the powder onto the fruit or simply lick it from our hand. The powder had a savory flavor and was a little salty. I can’t remember the name, but from a couple of google searches I’m quite sure that it was a dried plum powder – li hing mui (or just li hing). I see that it’s available from several sellers on Amazon (In fact I just ordered a pack from Hawaii – if it’s the same I used to eat with guavas as a child it will bring back a lot of memories when it arrives!). I found a couple of blogs showing guava with plum powder and masala salt which suggests that there are probably several spice powders used together with guava. The Wikipedia entry on guavas also mentions them being eaten with soy sauce and vinegar (occasionally with sugar and black pepper) on Hawaii, and with a pinch of salt and cayenne powder/masala in Pakistan and India.

Guavas taste even better with a salty/savory dip! For the picture I combined ground star anis with salt and sugar.

As I started to search for combinations of fruit and salt I was overwhelmed by all the different combinations I found. Salt (and other salty food items) are often mixed with other ingredients such as chili or lime. Here’s a small selection of what I found in no particular order:

salt + sugar + chili (Prik-kab-klua)
salt + sugar + chili + lime (Muối ớt)
salt + chili sauce
salt + masala
salt + cayenne
soy sauce
soy sauce + vinegar (+ salt/pepper)
fish sauce
fish sauce + sugar + chili
fish sauce + black pepper
tajin = salt + chili + lime juice
kiam-muy-hoon/kiamuy
li hing mui (dried plum powder)
dried plum powder + sugar
bagoong (salted shrimp paste)
prosciutto
…

One of the few many salt + fruit combinations that has made it to Europe: prosciutto ham with honey dew melon (and some drops of balsamico syrup)

Other more specific fruit/salt/savory combinations I found were:

bananas and guavas with salt and fresh pepper (served in India)
chili salt with fruits such as Granny Smith apples, plums or oranges.
peaches with chili/lime/salt
pomelos with salt and red chillis
Hawiian margarita with Ling Hi Mui powder
…

It seems that eating fruit with salt is far more common in warm countries where an additional intake of salt is recommended due to perspiration. (Update: Lisa comments on her Swedish blog that it could be due to the fact that there are more supertasters in Asia – they are more sensitive to bitterness, hence the additional use of salt) And I admit that my craving for salt does increase when it’s warm. But there is more to this than physiology – the few combinations I have tried are indeed mouth watering – even when tested in cold Norway. And thinking about it, it is really fascinating how plain table salt – one of the simplest (chemically speaking) ingredients we have in the kitchen – has such a repertoire in combination with fruit. There is certainly a lot to try out in the kitchen now – and perhaps some inspiration from Asia for chefs as well?

If you know about or have tasted other fruit + salt combinations, please leave a comment in the section below

Reference:
[1] Keast, R. S. J.; Bresling, P. A. S. “An overview of binary taste-taste interactions” Food Quality and Preference 2002 (14), 111.

One of the good things about living in Oslo are the coffee bars. Norwegians drink a lot of coffe (a healthy dose of 9.9 kg anually per capita, only second to the Finnish) and perhaps that is one reason why there are so many coffee bars around. One of the best (if not the best) is Tim Wendelboe at Grünerløkka. Tim Wendelboe is a previous WBC champion (2004) who now owns a coffee bar and a micro roastery bearing his name. If you visit Oslo and the Grünerløkka area you should definitely walk the additional 200 m from the crowded “Kaffebrenneriet” at Olaf Ryes plass to his shop. And if you live outside Oslo you can buy freshly roasted coffee directly from his website and read more about his coffee adventures in his blog. If you read Norwegian you might also be interested in his recent book “Kaffe”. I’ve enjoyed a lot of coffee from Tim Wendelboe, both in his shop and as beans at home on my Rancilio, and having finished my post “A pinch of salt for your coffee, sir?” I decided to send Tim an email and ask him about his experiences with salt and coffee. I got a very kind reply were he invited me to come and do some tests in his shop. Now that’s an offer I couldn’t refuse!


The coffee roaster is literarily right in the middle of Tim Wendelboe’s coffee shop at Grünerløkka in Oslo.

In his email reply Tim mentioned that he had heard about salt and coffee, but that he’d never done systematic experiments with it. Interestingly, he also mentioned that in Ethiopia it’s common to serve salted popcorn with coffee! What fascinates me the most from all the comments to my last post is how salt-in-coffee is done more or less around the world. It seems as if many know of it, but hardly ever talk about it!

Measuring the small amounts of salt needed is easy with an analytical balance with a 0.0001 g readout, whereas it is impossible on a scale with a 0.1 g readout (which is what you would typically find in a coffee bar). Therefore, as a preparation I had practiced a little at my work, measuring out salt with a standard spatula. When heaped I’d get around 45 mg of salt, when leveled I typically got 15 mg and with the spatula visible all around the salt I managed to repeatedly weigh out about 10 mg of salt. With this I was ready for some experimenting.

A traditional coffee pot (designed by Grete Prytz Kittelsen) was used for the first extraction.

We started off with a coffee from Square Mile Coffee Roasters, a Colonia San Juan. This is a darker roast compared to Tim’s typical roasts, and he suggested this could be a good starting point to test how salt affects bitterness. Measuring out 65 g of a relatively coarse grind, allowing it to steep in 1 L hot water for 5 min + 1 min (after stirring) and dividing the prepared coffee in three, we then added about 45 mg salt to the first 300 mL of coffee. To the second third we doubled the amount of salt and kept the last as a reference. The first observation was that even at 150 mg/L (corresponding to 45 mg/300 mL) the effect of salt is very noticeable. Tim’s immediate response was that the coffee with salt had lost some of it’s structure, appeared less acidic, had somewhat less bitterness, but at the same time was richer and heavier in the mouth. He’s a pro with years of cupping experience whereas I had my very first go with the cupping spoons, so I’ll never get my experiences down on paper like that. They were definitely different, yet both were drinkable. - This could maybe be useful for cold coffee drinks, says Tim. When cold, the bitterness of coffee becomes more noticeable. One way of combating this is by adding sugar. But with a general consumer trend towards less sugar, a tiny pinch of salt could maybe prove useful. Tim said he’d do more tests, and who knows – maybe this year’s summer special will be an ice coffee with a pinch of salt?

We continued with a newly roasted espresso which hadn’t finished it’s degassing yet, giving it some burnt aromas. The effect of salt (10 mg for a double espresso) were more or less like in the previous test. - It’s as if the one with salt is more viscous, says Tim, adding that he values acidity in espressos and that somehow the salt removes some of this acidity. From the litterature on binary taste interactions it is known that low/medium salt concentrations will enhance sourness whereas higher salt concentrations will suppress sourness. Based on this it sure seems as if we hit the “high” level with respect to sourness (but the experiments we did were of course in no way scientific). I tried one espresso with roughly 2-3 times the amout of salt (20-30 mg for a double espresso). When first tasting it carefully in the front of my mouth I felt it was almost sweet whereas Tim spit it out immediately. I then tasted it again towards the back of my tongue and this time I felt the salty taste too. Quite fascinating how the tasting technique gives different results. These tests also demonstrate how bitterness is linked to and influenced by sourness.

To end it all we tried adding salt to espresso with steamed milk. It turned out that a dose of 10 mg for a double espresso was difficult to discern from the reference. We added more salt and were surprised how much salt could actually be added before it became noticeably salty. But it remains to be seen if salt will make any difference in the end when adding milk. With all it’s proteins, milk is so powerfull in altering the coffee flavor and damping bitterness that a little salt simply won’t make such a big difference.

Apart from the potential use in cold coffee the I guess one conclusion is that high quality coffee from a micro roastery is good by itself. There is no need for salt, but salt can be used to knock out some acidity (as well as some bitterness), resulting in a coffee which is more compact, not so fresh, but with a fuller taste, mellow … and simply different. But as always – more experiments are required. I also think that the effects of salt were best demonstrated with plain hot water extraction. Espressos are so overwhelming and strong that the taste buds quickly tire from tasting a couple in a row. Lastly, I’d also be willing to hypothesize that salt can do more for average (or even poor) coffe beans and/or poor extraction technique than with first class beans prepared in the best possible way. And if you’re in doubt wheter there is a large difference between the quality of coffee beans, take a look at the picture below.

Coffee beans are pale green before they are roasted. The difference between good beans (top left) and bad beans is significant, as Tim showed me. If you think the bad beans are discarded – think again. They’re sorted out one by one and end up in your super bargain coffee!

I prefer my coffee black, and politely decline when offered milk and sugar. However, if offered salt I would probably smile and say “Yes, please!” Salt???! It turns out that adding salt to coffee is not as weird as it may sound at first. There is a tradition for adding a pinch of salt to coffee in Northern Scandinavia, Sibir, Turkey and Hungary. And when available, such as in coastal areas where fresh water from rivers mixes with the salt sea, one would simply use brackish water when preparing coffee. This water typically has a salt content of 0.5-3%, which is lower than the average 3.5% in seawater. This results in a more intense taste and more foaming. And if living far from the sea, the Swedish food blogger Lisa Förare Winbladh let me know that in Northern Sweden one would deliberately add salt if using melt water from glaciers for making coffee. But tradition aside, is there a scientific explanation of this widespread tradition of preparing coffee with addition of salt?

The first thing that comes to mind is that salt reduces bitterness. And to be more precise it is the sodium ion (Na⁺) that interferes with the transduction mechanism of bitter taste. But interestingly the mechanism behind this is not fully understood! One of my very first blog posts was about tonic water and how one by adding salt can suppress the bitter taste and make tonic water more or less sweet. It’s a fascinating experiment that you should try at home. Expect to use about 1,5-2 g salt for a glass with roughly 1,5 dL (150 g) of tonic water. It’s a good idea to start with a little salt and taste it as you go.

Try adding a little salt to tonic water – the effect is quite surprising: The characteristic bitterness from the added quinine disappears!

Bitterness is an important flavor in coffee, but under less-than-optimal extraction conditions it can be too dominant. Generally bitter tasting compounds are less water soluble than other coffee flavors, hence the bitter compounds are extracted towards the end of the brewing. High temperatures (close to boiling) and long extraction times also favor bitterness. In that respect the coffee percolator is known to produce rather bitter, over-extracted coffee due to near boiling temperatures, and such coffee would most likely benefit from a little salt! And before the percolator came the ground coffee was just put into the boiling water and then left to settle. I can really imagine how brackish water could actually benefit

But the salt need not be reserved for over-extracted coffee. I’ve tried using salt both in a drip coffee maker and in the filter basked when pulling an espresso. The tests were very un-scientific, but the tiny amount of salt does dampen bitterness and change the coffee taste (but the coffee does not have a salty taste). Since I lack cupping experience, I certainly lack the language to describe how salt influences the taste, so I leave it up to you to try it out! And maybe some baristas with cupping experience can fill me out on this and do some tests?

In stead of just using plain salt with coffee, cured ham would signal rafinesse if served in central Europe, whereas in Northern Sweden there is a tradition for serving dried meat with coffee. The Swedish author Mikael Niemi describes this in his novel Popular music from Vittula:

“… and then the pièce de résistance among all the sweetmeats: a hard, brown lump of dried reindeer meat. Salty slices were cut and placed in the coffee, chunks of coffee-cheese stirred in, and white sugar lumps were held between the lips. And then, fingers trembling, we all poured the coffee mixture into our saucers, and slurped our way to heaven.”

With cured ham, apart from the salt-coffee interaction, one also has the combination of meat and coffee. From previous flavor pairing rounds TGRWT #1 and #5 (chocolate/coffee and coffee/meat respectively) we have seen that coffee and meat in some ways approach each other and are actually a good combination. A secret tip BTW is to add a little coffee to your beef stocks for extra depth and richness – this works because coffee shares many impact flavors with browned meats due to the Maillard reaction.

Now I’m curious – are you aware of coffee-salt combinations in your own country? Please tell me about it! And if you try a pinch of salt in your coffee – how did it taste?

Update: Read about my tests of coffee with salt at Tim Wendelboe’s coffe shop

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Some articles that discuss the role of sodium ions (Na⁺) in suppression of bitter receptors:

Breslin, P. A. S; Beauchamp, G.K. “Suppression of Bitterness by Sodium: Variation Among Bitter Taste Stimuli” Chemical Senses 1995, 20, 609-623.

Breslin, P. A. S; Beauchamp, G.K. “Salt enhances flavour by suppressing bitterness” Nature 1997 (387), 563.

Bresling, P. A. S “Interactions among salty, sour and bitter compounds” Trends in Food Science & Technology 1996 (7), 390. (free download)

Keast, R. S. J.; Breslin, P. A. S. “An overview of binary taste–taste interactions” Food Quality and Preference 2003, 14(2), 111.

In addition to suppression of bitterness, salt can enhance sweetness at low concentrations and umami flavors at higher concentrations (more about this in part 5 of “Practical tips for molecular gastronomy”).

Rob Mifsud, perhaps best know for his Hungry in Hogtown blog has interviewed Hervé This. At the end of the interview Hervé lists 10 elements of basic kitchen knowledge. Some may seem obvious, but they are not, according to Hervé. Here’s the list so you can judge by yourselves:

1. Salt dissolves in water.
2. Salt does not dissolve in oil.
3. Oil does not dissolve in water.
4. Water boils at 100 °C (212 °F).
5. Generally foods contain mostly water (or another fluid).
6. Foods without water or fluid are tough.
7. Some proteins (in eggs, meat, fish) coagulate.
8. Collagen dissolves in water at temperatures higher than 55 °C (131 °F).
9. Dishes are dispersed systems (combinations of gas, liquid or solid ingredients transformed by cooking).
10. Some chemical processes – such as the Maillard Reaction (browning or caramelizing) – generate new flavours.

A very simple chemical that neutralized/modifies bitter taste is salt – and the best thing is that you don’t have to be a supertaster to test this. For a simple experiment, take tonic water, taste it and then stir in some salt (start with 1/2 teaspoon). Taste it again – if you can still taste the quinine, add a little more salt. At one point the bitter taste has almost disappeared! This principle might work for cucumbers and melons as well, but of cource there could be totally different taste mechanisms responsible for the bittertaste in the two cases.

It might sound strange to add salt, but in Asia, it is not uncommon to eat different fruits with salt. I am aware of unripe mangoes, guavas and honey dew melon are eaten with salt, a salty spice and soy sauce respectively. Also – some people add a small amount of salt to the water when brewing coffee – this reduces bitterness and rounds of the taste. One last example is how salty food can make a young red wine with plenty of tannins more pleasent to drink. Tannins (polyphenolic compounds) can be both astringent and bitter, depending on their molecular weight (low molecular weight tannins are predominantely bitter whereas larger molecules are more astringent).

BTW, this has also been treated scientifically. See for instance: Breslin, P. A. S; G.K. Beauchamp, “Suppression of Bitterness by Sodium: Variation Among Bitter Taste Stimuli” Chemical Senses 1995, 20, 609-623 (link).