Flavour: A User’s Guide to Our Most Neglect Sense, by Bob Holmes (I read the UK edition, hence the spelling mismatches you might notice).

This is one of those pop-science books, written by a journalist, that catches the imagination but probably requires some caution. It appears well researched and has copious cited sources, which is very good, but also contains some dubious claims that do not inspire confidence. This, for example, seems relatively arguable:

Sometimes, these experiments point to another noteworthy fact: Smells and tastes often go together differently for different cultures. For example, caramel odor doesn’t enhance sweet tastes for many Asian people, who are likely more used to encountering caramel in savory dishes instead of the sweets that Westerners are used to. The same thing happens with benzaldehyde, the main component of almond aroma. It enhances sweet tastes in Westerners, who usually encounter almond in pastries. But for Japanese, benzaldehyde enhances umami taste, because almond is a common ingredient in savory pickles.

Flavour, page 93 (ebook edition)

I have never seen any “savory pickles” with almonds in Japan. I have seen savory snacks with almonds in them here, though, so perhaps it’s just a simple mistake of which savory thing?

That being said, the fundamental arguments of the books are hard to refute: that our sense of flavor is primarily focused in our nose, and that it is formed by a complex arrangement of genetically influenced physical sensory apparatus and a vast array of cultural influences, such that the likelihood of two individuals having an identical sensory experience of the same flavor is almost impossible, but that shouldn’t get in the way of enjoying and exploring it.

There are many points in this book where I found myself cackling with glee as they reinforced things that I had been increasingly seeing myself about the obsessions of the gourmet/wine/sake world, like how even the most vaunted experts are working with flawed apparatus that can only accurately identify three or four aroma compounds at a time (see p. 52), or how flavor really only exists in the head:

Gordon Shepherd puts it best: “A common misconception is that the foods contain the flavours,” he says. “Foods do contain the flavour molecules, but the flavours of those molecules are actually created by our brains.” Thought itself, in other words, is one of our flavour senses. The brain constructs flavour by piecing together inputs from virtually every one of our sensory channels, plus inputs from thought, language, and a host of other high-level processes like mood, emotion, and expectation. That makes flavour a remarkably complex and changeable concept. It’s a wonder we can talk about it coherently at all.

Flavour, p. 104

The changeability is the real crux. Tasting exercises try to turn this infinitely variable and subjective sense into something objective and reliable, but it just isn’t. And there is more and more evidence that even the “pros” are simply better trained at putting words to their sensory experience, not actually better at sensing.

One particularly fascinating episode comes from winemaker and former oceanographer (a scientific minded person, in other words) Bob Hodgson of California. He noticed that he was completely unable to predict how well his wines would do in contests.

With his scientific turn of mind, Hodgson started to wonder why the very same wine could garner a high score last week and a low one this week. Could you really trust the judges’ scores, he wondered? Hodgson must be a persuasive guy, because somehow, he managed to convince the California State Fair to let him find out.
Judges at a big competition like the California State Fair taste about 150 wines every day, organized into 4 to 6 “flights” of 30 wines each. The wines within a flight are presented in identical glasses marked with identifying codes, so that no judge knows the identity of any wine he or she is tasting. Each judge individually—no discussion at this stage of the judging—gives each wine a numeric score on a 20-point scale. (Actually, the fair uses a 100-point scale like the ones you sometimes see on the shelves at your local wine shop. But any wine that’s halfway drinkable scores at least 80 points, so for all practical purposes it’s a 20-point scale.)
With the collaboration of the contest organizers—but unknown to the judges—Hodgson arranged that for one flight per day (usually the second), three of the thirty wines would actually be identical samples, poured from a single bottle of wine but given different code numbers. If judges’ scores are a true reflection of a wine’s quality, then you’d expect these triplicate samples ought to receive identical scores—or at least somewhat similar scores, allowing for a little bit of imprecision in the judges’ ratings.
The results were shocking.16 “We did everything we could to make the task easy for the judge: same flight, same bottle. And nobody rated them all the same,” says Hodgson. Only about 10 percent of the judges scored the three samples similarly enough that they awarded the same medal to each. Another 10 percent gave wildly different scores, giving one glass a gold and another a bronze or even no medal at all, and the rest fell somewhere in between. And that wasn’t just because some judges are better than others: judges who were consistent in one year were no more likely to be consistent the next year.

Flavour, pp 105-106

Hodgson himself found that his experience of his own wine was often largely guided by outside influences as much as what was in his glass. So, in conclusion:

All this points to an uncomfortable conclusion: If trained judges and experienced winemakers don’t consistently prefer one wine over another, then maybe there’s no real basis for calling some wines great and others merely good. And that may be how it really is, though it’s hard to find many wine people who will agree.

p 106

The gist of so much of this can really be summed up by saying: our enjoyment of a thing is only partly contingent on the thing itself, and most of it is based on the situation around our enjoyment. Our mood, the weather, the glasses we’re using, the people we’re with, it’s all part of it.

One particularly visceral section is a long quote from flavor chemist and wine expert Terry Acree on the subject of wine pairing, which I think almost certainly has much to teach us about sake pairing, as well:

What does it mean to “go together”? My mother was an interior decorator, and when I was about five, I walked in and said to my mother, “My favorite color is red.” And she said, “No it isn’t, kid. That’s the stupidest thing I ever heard of. Nobody has a favorite color. Color has a place, and you have to find out where it belongs and where it doesn’t belong. It can only be your favorite if it’s in the right context.” So the first thing I’ve got to say about wine and food pairing is that it’s completely contextual, and almost entirely individual. It makes no sense to write a book on wine and food pairing, except to say there is such a thing as wine and food pairing, and go figure it out for yourself, because it’s your own pairing that counts.

Flavor, p. 192

If flavor truly is this complex experience influenced by almost countless variables both internal and external, ranging from genetics to mood to the weather, then trying to build bedrock principles to guide that experience is a futile thing that only works if everyone involved agrees to just nod and go with the flow–an experience I often find myself having during guided tasting.

The ending message of this book is exactly what I find myself trying to tell people about sake: Be mindful, and enjoy it in your own way. Or, as he says

Remember, even expert perfumers and flavourists can’t accurately identify more than three or four aromas from a mixture. In something as complex as wine, that means the experts’ flavour identifications miss the mark pretty often. (You can easily verify that by comparing two critics’ reviews of the same wine and noting their lack of overlap.) The bottom line is that accuracy doesn’t matter. What’s important is that coming up with a description forces me to pay attention, and paying attention enriches my flavour experience. It slows me down, so that meals become a time for dining, not merely for eating.
There’s a world of flavour out there waiting, and it’s ours to enjoy.

Flavour, p. 224