Thursday, October 22, 2009

Umami: In Search of the Fifth Flavor

I think I can remember in grade school learning how there are four tastes: sweet, sour, bitter and salty. (Incidentally, there was a girl I went to college with whom I called "Salty" -- that might sound obscene, but it's not. Someone gave her that nickname for "throwing salt in people's game." Now I guess it just sounds stupid. Anyway...) I even remember seeing a little diagram that showed where the tastebuds that detected these different flavors were located on your tongue. It turns out that like so much we learned in school (glass is a liquid, really?!) that diagram was bullshit. There are taste receptors all over your tongue that can detect any of the tastes; just try putting some salt on the tip of your tongue where the sweet tastebuds are supposed to congregate.

Also, everybody now agrees that there is a fifth taste called "umami." Umami's been around for awhile: I think I first read about it around 5 years ago. I started thinking about umami again earlier this month after I mentioned it to Amanda and realized that I still wasn't really sure what this taste sensation is like. So I decided to write a blog post and to try and get a better idea what umami is all about. I also wanted to find some examples of foods which illustrate this elusive fifth element of taste.






The Four Classic Tastes

Before we start on our quest to uncover the secret of umami, maybe we'd better make sure we have a good grasp on the four classic tastes. Sweet and salty are no-brainers -- sugar makes food sweet and salt makes foods salty --, but how clear are we on the difference between sour and bitter?

Sour is the flavor that characterizes those ingredients which chefs say add acid to a dish such as lemon and vinegar. The sour tang is what makes greek yogurt (and skyr) taste different from regular ole Dannon/Danone yogurt; it is also what distinguishes buffalo mozzarella from cow-milk mozzarella. The sour taste sensation is basically your tongue detecting something acidic (i.e. something with a PH level below 7.0) in the food you're eating such as citric acid, a chemical compound present in citrus fruit. Citric acid levels are much higher in lemons and limes than they are in oranges, tangerines and grapefruit which explain why they are more sour. Meanwhile, the acid in vinegar is called acetic acid (acetum is the Latin word for vinegar. In Italian the word is aceto.).

The bitter taste, on the other hand, is your tongue detecting some other kind of chemical in the food you're eating. Bitter foods include a lot of greens which are used in Italian cuisine such as dandelion greens, escarole, broccoli rabe (one of my mom's favorite foods) and what we in the States call arugula (the Brits call it "rocket" and in Italian it's usually called "rucola"). Also olives and brussel sprouts. Bitter drinks include coffee and tonic water (it's the quinine that makes tonic water so bitter). Scientists say that our tongues' bitter taste receptors are the most sensitive. The evolutionary reason for this, and for why most people find overly bitter foods unpleasant, is because many toxic substances trigger this taste sensation. Another interesting fact is that there are a couple of chemicals which trigger a bitter taste sensation for some people and not others. These people are sometimes called "supertasters."


The Discovery of Umami

The story of umami begins in 1908 at Tokyo Imperial University. There a chemist named Kikunae Ikeda was studying dashi, the kelp broth which is a basic ingredient in Japanese cooking, and he managed to isolate glutamate (i.e. glumatic acid) as the chemical which gave it its characteristic flavor which he dubbed "umami" (旨味) after "umai" (うまい) which means something like "delicious" or "savory" in Japanese. Ikeda went on to find that glutamate was also present in other savory foods, and in 1912 he presented his findings to the International Conference of Applied Chemistry in Washington, DC stating that “those who pay careful attention to their tastebuds will discover in the complex flavor of asparagus, tomatoes, cheese and meat, a common and yet absolutely singular taste which cannot be called sweet, or sour, or salty, or bitter…."

After this it was discovered that other chemicals such as guanylate which is found in shitake mushrooms and inosinate found in bonito (dried fish) flakes were also associated with the umami taste. More recently, in the '70s and '80s, studies by scientists in other countries have confirmed that umami triggers a distinct neurological response from the other tastes (like saltiness) and that the human tongue has seperate umami taste receptors. Since then, awareness of "umami" as the fifth taste has spread in the culinary world. It was even featured in one of the challenges on this season's Top Chef where one of the cheftestants helpfully defined it as "you know... it's umami... it's the fifth flavor." Thanks for clearing that up!


The Taste of Umami

So that's all great but what does umami actually taste like? Some attempts to translate the term into English have yielded results such as savoriness, meatiness, heartiness and brothiness. As these words suggest, umami is actually much subtler and harder to pin down that sweet, salty, sour and bitter. Further complicating the picture is the fact that umami foods are often salty as well, so you need to try to put the saltiness aside and focus on what else is there. That said, in order to really understand the umami taste sensation I think we need to discuss (and eat) some different foods which are rich in umami.


Foods Rich in Umami

Broths usually have an umami taste whether we're talking about beef broth or vegetable broth. In addition to Japanese style soups made with kombu kelp, shitake mushrooms or bonito flakes, french onion soup is also very umami.

A lot of dried and fermented foods also tend to have a strong umami taste. Marmite/vegemite, the yeast extract spread "enjoyed" by Britons and Australians, is very umami (in addition to being very salty) as is Worcestershire sauce, fish sauce (made from fermented anchovies), soy sauce and oyster sauce. Fresh oysters and shitake and enoki mushrooms contain umami flavors which are intensified when they're fermented or dried. Other umami foods include nori seaweed (encountered in sushi rolls and seaweed salads), caviar and salmon roe, parmesan cheese, and tomatoes (that's why they call them "beefy").

The food additive MSG (monosodium glutamate) is the most common spice used to enhance foods' umami taste.  MSG gets a bad rap for being artificial and for its unappetizing, chemical name, but its actually produced by fermenting carbohydrates.  A lot of people also claim they have a vague allergic reaction to MSG, e.g. that it gives them a headache, that it makes their fingers feel puffy or numb, or that it causes asthma-like symptoms.  I'm not 100% anti-MSG, but one time when I was at the supermarket with Nicole I found one of those giant spice containers (like you might get garlic powder or red pepper flakes in) filled with MSG and we were both like "Gross! Who would buy that?"   


Primal Strips Meatless Jerky


Speaking of umami... I noticed last week that at the healthy food/juice place where I like to get lunch (the Juice Joint Cafe of Vermont Avenue) they started selling these vegan jerky strips. I was kind of intrigued by these and the flavors that stood out were Thai Peanut with Seitan and Hot & Spicy Shitake Mushroom. So yesterday I decided I was going to go for it and try one. I was actually leaning towards the Thai Peanut but Nicole (perhaps the only other person I know who would be intrigued by the prospect of vegan jerky strips) convinced me to go for the Hot & Spicy Shitake Mushroom ("I do love hot & spicy," I remember typing). So anyway I bought some with lunch and ripped into it later that afternoon.

The taste was... interesting. I remember thinking "wow that's umami!" Shitake mushrooms and soy sauce are ingredients #1 and 3, respectively. To tell you the truth, I'm not sure if I liked it: the flavor is complex, and I can't say whether I might grow to enjoy it (this happens to me all the time. I have ambiguous feelings about some new food, but then later I start to think about it, and then to sort of crave it, and then I try it again and pronounce that I love it. I'm weird, I know.) or maybe I'll end up deciding that it's just nasty. Next time I'm going to try the thai peanut; I bet that will be less complicated.


Conclusions

So I feel like I have a bit of a better idea what umami is all about now. I still don't really know how to describe it -- calling it meaty or brothy is really just saying that meats and broths have this taste, I guess savory is slightly more evocative. I do feel, however, even though my concept of umami is fuzzy that I enjoy and actively seek out foods which have this taste. If you want to go on your own quest to figure out the essence of umami I'd recommend you try something like vegemite, an authentic Japanese soup (like miso soup) with a dashi base and/or with shitake or enoki mushrooms, or maybe a good French onion soup. If you can find it and you're adventurous you can even try that "interesting" Primal Strips Hot & Spicy Shitake Mushroom jerky and let me know what you think.


For additional information, I direct you to the Umami Information Center.


Images: Umami map taken from umami information center; dashi photograph found on humble bean blog; marmite photo; marmite photograph taken from ryansgoblog; hot & spicy jerky photo taken from primalspiritfoods.com .

3 comments:

nola32 said...

this arugula is so bitter! it's like my algebra teacher on toast.
oh and i'm totally a supertaster (or so says the bbc!)

Rafael said...

Our sense of taste doesn't just warn us about foods that are unripe or may be poisonous, it also gives our brain preliminary information on the type of nutrients that will need to be digested.

Umami compounds, i.e. early metabolites of selected amino acids, basically announce that easily digestible protein is on the way. Saliva production goes up, stomach enzymes are produced etc.

However, the thyroid, heart etc. also become more active. After all, back in the stone age, protein was scarce and humans would sometimes have to fend off wild animals and/or other humans. A unexpectedly large dollop of glutamates can therefore result in an "umami high", which is best dealt with via some exercise after the meal, amourous or otherwise.

Protein that has been denatured via drying, heating, acidulation, brining, solution in alcohol and/or fermentation with benign bacteria or molds is more bioavailable than raw meat or fish. Moreover, if done correctly, it also greatly reduces the risk of food poisoning.

Another factor is surface area to volume: higher means peptides in the stomach can break down the proteins into amino acids more quickly and completely. Hence, protein that arrives in liquid, pasty or at least easily chewable form is greatly preferred.

Hence, an protein-poor but umami-rich amuse-bouche or starter course will prime the body for a protein-rich main course. It doesn't much matter if it's lean, it doesn't even need to have a lot of umami itself. Even something bland but "healthy", e.g. poached chicken, will taste better and be more filling if the body is suitably primed. This is true even if the portion is (much) smaller than you are used to. Voilà, nouvelle cuisine.

However, if an umami-rich starter or the later courses in the meal fail to deliver the promised protein, you can end up with the old "fool me once, shame on you, fool me twice, shame on me" scenario. The brain concludes that umami isn't all it's cracked up to be and the related receptors are numbed down. Ergo, it takes ever-higher levels of umami seasoning to replicate the original kick. At some point, Chinese restaurant syndrome kicks in and your taste buds are ready for rehab.

Summary: whenever you eat something that is new to you, including umami-rich stuff, your brain is learning. Often, the initial hunch proves correct. However, there's nothing at all weird about being a little ambivalent about the initial experience. As long as the nutritional promise is kept and there are no adverse health effects, the brain will eventually give the new food a firm thumbs up.

Hence the term "acquired taste". See toddlers for details.

Meeg said...

Very interesting! This reminds me of how some people suggest that artificial sweeteners mess you up because they send your body/brain the message that you're about to get some sugar, but then when the sugar never comes your body/brain become confused about how it should interpret the signal in the future.