In the general population, 75% are
considered “tasters,” who experience a bitter taste of PTC, and 25% are non
tasters. The non-taster effect is considered a recessive genetic trait. The “taster”
trait is assigned to the “PTC gene” TAS2R38 discovered and so named in 2003. But this isn’t the only gene involved in bitter flavor,
in fact over 30 genetic markers have been identified as involved in bitter
taste. Nevertheless, the PTC gene is so reliable that it was used in paternity
tests in the 1940s and onward until more complex DNA tests were invented. And
the trait varies somewhat with ethnic origin, at least in Europe. Large studies
performed in various countries of Europe (with N>100, as high as N>1000)
found non-taster rates as high as 37% in Slovenia and as low as 16% in Uẑice,
Serbia.
On the other hand, those other 30 genes
certainly affect bitter taste as well. In a very small study (n=8), Henkin
& Gillis (1977) served a pie made from the fruit antidesma bunius berries. Two people stated the pie was “extremely bitter
and inedible.” The other six people found the pie “pleasant tasting, enjoyably edible
and sweet.” The researchers then did the PTC test. The two people who found the
pie bitter found PTC not bitter, whereas the other six people who thought the
pie sweet turned up bitter on PTC. Obviously PTC tasting status had nothing at
all to do with who thought those berries tasted bitter. Only eight people, well
I guess by now we have a larger sample pool just on a 2014 New Amerykah pie. How
many of you finished off your cake and how many put it away hoping for better
days?
Maybe the whole business of what tastes
bitter or sweet has something to do with childhood. Studies of babies have of
course shown a preference for sweet tastes, and formula feeding versus breast
feeding apparently merited enough study of effects for tastes later in life. In
a study controlled for PTC gene variation, however, young children who were
asked to taste items and then assign the bitter ones to Oscar the Grouch and
sweet ones to Big Bird showed no racial or cultural differences between each
other.
Interestingly, the children and mothers were studied with regard to
bitter turning sweet, what we tea drinkers might consider “huigan.” Apparently
this aspect of bitter tasting is also genetic. The researchers did conclude
that children may be more alike to one another, because the children differed less
from one another than they did from their mothers. Why then did children differ
from their mothers? The study was inconclusive as to whether development of
taste is affected by aging or by what is called “forced experience.” That is, the
idea that we develop tastes based on what we are given to eat with no choice
involved. In that theory, eventually we develop our adult taste preferences based
on what our parents gave us to eat when young.
I can certainly see this effect in my
own family. My mother cooked plain meat and served raw vegetables most days. (She
was an Adele Davis mom, and in truth really wasn’t much of a cook). When my
father remarried, I couldn’t adjust to my stepmother’s heavy sweet gravies and
casseroles. In turn, I served my son plain meats and fish with raw vegetables,
and his taste as an adult remains the same. My relatives complained he wouldn’t
eat the casseroles and gravies when he visited. But my son still eats raw
vegetables of all sorts daily with relish, and only reluctantly will eat cooked
veggies even at the age of 25 when supposedly his taste should “mature.” I
prefer mine raw or steamed lightly as well. To a large extent, two generations
of my family are affected by the “forced experience” of one person.
But let’s go back to the berry pie. Why
would one person decide that pie tastes sweet and delicious, and another person
can’t stand to eat it, especially when PTC taster status did not factor into
the conclusion? The truth is taste is complex, and if bitter taste truly
involves 31 genes, the factors play out in such a confusion of individual differences
that perhaps calling taste “subjective” is functionally the most useful. How useful
is it to say “well my taste here is due to my 31 genetic markers?” even though
such a statement is certainly quite “objective.”
An interesting theory I read is that the
development of sour and bitter taste may
have something to do with specific environmental adaptations designed to
identify poisonous plants and avoid them. We know that plants develop
bitterness as a way to protect themselves from insects. So perhaps my idea of sour
or bitter is connected with not eating that poison sumac in the yard (though I
rather relish the stick marrow). But my
poison sumac may not grow where you live, and you have something else you must
avoid eating in your yard.
Actually, if this theory holds true, the
plants I’m truly evolved to avoid must be in northern or eastern Europe, rather
than the Americas, because I’m only a second generation born here. Two
generations isn’t really long enough for my genes to mutate very much. My
sister had her DNA profile done and assuming she is truly my sister I can
confirm from her results that I have the ability to taste pickle vinegar, I
have a lactose enzyme which means I can digest and enjoy bovine milk, and I can
smell asparagus in urine. And we learned that my grandfather was only 76%
Ashkenazi which means somebody fooled around at some point without telling
anyone, and subsequently everyone conveniently forgot.
In other words, we may believe we have
an ethnic or genetic experience that guess what, we may not truly have. My
sister swore she is lactose intolerant, one of the reasons she wanted a genetic
test done. But in fact she carries the digestive gene, so her problems with
milk must be due to another reason. This has to dampen pronouncements across
the board that cow’s milk is bad. We do know that persons of Asian descent may
lack the lactose enzyme, but this doesn’t mean we can conclude milk is poison
or bad for the body if some people have a real ability to digest it. In like
fashion, I don’t know if bitter taste is related to a skill of detecting
poisons in one’s ancestral setting, but when considering the lactose enzyme, at
least some environmental adaptation seems like a reasonable theory to me. One
wonders with all the movement of people these days, how adaptations like taste
will evolve in new directions in a few hundred years, and how difficult running
a restaurant might be at that point because so many variations in taste live
side by side.
Of course this is a tea blog so you all
know where this is heading. Most tea blog readers are asking a question of a
tea review: should I buy it?
While taste is not entirely subjective, the
objective factors are surely confounding enough to make them functionally subjective, in the end, when reading “advice” from supposed experts. I think enough
evidence here suggests that you can buy what you like without apology. You don’t
have to like sheng. You don’t need to appreciate shou. One person’s gyokuro is
another’s soggy wet spinach. And one man’s fabulous first steeping is another
man’s tossed storage brew. Nobody needs to apologize for their happiness with
Lincang tea, or for their distaste of smoky tuos or spore-filled heicha. For
sure one person’s dry storage is another person’s musty wet basement.
People shouldn’t feel inferior because
they are not on the “Sheng train.” You can adore your First Flush Darjeeling
and ignore anyone who complains. Beautiful, yes stunning teas of every sort are
ours to buy these days. If you get a tummy ache from a tea, why keep drinking
it? Buy another tea that makes you feel happy and relaxed. And nobody else’s 31
genes can tell you that yours aren’t experienced enough, or sophisticated
enough, sensitive enough or appreciative enough because that tea tasted like
crap. Your opinion is what matters, anything
else is group think.
And you don’t have to buy it. Unless you want to.
Requiescat in Pace
I loved the bitterness ramble! I read a book a while ago about people who love and crave bitter notes in food and how taste evolved, gastronomic history is a passion of mine so I geeked out a bit. But geeking aside you make many excellent points, tastes are so complex and varied, it's amazing and no one should feel down for not liking a tea/liking a tea.
ReplyDeleteConcerning milk, I've read an interesting theory that states that most people who get abdominal discomfort after drinking milk are not actually lactose intolerant,but the problem lies with milk processing. It seems that through centrifugation the size of the molecules decreases, thus allowing them to pass through the bowel unhindered and cause local inflamation. The problem can be solved by drinking fresh, unprocessed milk. The question of how easy it is to procure remained unanswered :)
ReplyDeleteYou are referring to homogenization. Fat is removed from milk and then re-added in the desired percentage. The bit you mention about the smaller particles is how the fat is removed, not unlike sieving.
DeleteI've had fresh milk, and depending upon what the cows eat and the farmer's handling, it can taste a bit gamey. Also, the cream rises rather quickly so you have to skim it unless you are drinking it immediately. The only way I will drink fresh milk would literally be my own cows or someone I know well. I wouldn't do it from a large production setting unless it is a taste test.
Aside from that, it might be the fat content for some folks. Perhaps they need higher fat content, the casein protein might be a bit too concentrated. The fat keeps the casein from curdling easily. If you've ever made a cream dish and tried using lower fat milks, compared to whole fat, when added to acids the whole fat casein will stay intact and creamy as long as you don't overheat the mixture. But low fat will curdle instantly in acid. So you don't get that creamy coating.
Thanks for commenting! Appreciate you thoughts.
Such an nice blog and useful detail about the products and all the information are very nice well done.
ReplyDeletebest product reviews