Are some flavour pairings known to work better than others (and if so, why)?

This is going to be kind of a rambly answer, partially copypasta from something I've written elsewhere:

Someone else said: An example is a sandwich that is made with roast beef, boursin cheese and caramelized onions.

Well.. that’s a fairly classic combination.

Here’s why, roughly.

Cheese contains a lot of the fifth flavour sense, umami. This sense is, roughly, ‘savoury’; that is, those things you eat that have a great deal of satisfaction, essentially. Tomatoes, cheeses, anything fermented–these are high in umami. One of the things that umami does is to heighten and enhance ‘meaty’ flavours in your food. So pairing cheese with beef becomes more than additive, it is multiplicative; the cheese enhances the flavour of the beef.

Likewise, caramelized onions are full of complex flavours due to transformation of the sugars within the onion. Consider the vast flavour difference between white sugar and caramel. The complex flavours arise from heating the sugars. This is, by the way, the real reason why you sear meat in a pan before roasting it in the oven. Browning the proteins in the meat is known as the Maillard reaction, and creates more complex, intensely savory flavours. Adding caramelized onions (or, classically with a roast, roasted potatoes and onions) plays off those flavours.

Moving on to ‘how the hell do they do that?’

Tasty food (ignoring texture) is built on two things: complement and contrast, similar to basic understanding of art.

Let’s start with the example given of duck and blueberries. These are flavours that contrast; the fatty meaty richness of the duck with the tart-sweet astringency of blueberries. Duck with fruit is a classic pairing from the mists of time; the acid of the fruit cuts through the unctuous mouthfeel of the fat while the sweetness offers a counterpoint to the savoury flavours found in duck meat, enhancing the flavour by contrast. There are, of course, infinite combinations of this. Consider very everyday examples: beer nuts (salty peanuts with a sweet coating), ice cream sundaes (cold sweet solid ice cream with hot slightly bitter liquid chocolate/fudge sauce), or the MetaFilter favourite of peanut butter and pickle sandwiches (soft creamy salty-sweet peanut butter with crunchy sour pickles). In each case, the contrasts enhance each other; in the duck example the sweetness of the blueberries makes the duck seem more savoury while the duck makes the blueberries seem sweeter.

Then there are flavours that complement each other. The easiest to understand is the combination of coffee and chocolate. Each brings dark, roasted, complex flavours to the table which marry incredibly well with each other because they match. And then there is (unless using wholly unsweetened chocolate) the contrast between bitter coffee and sweet chocolate, each flavour playing off the other.

So when you are looking at flavour combinations, you want to look at three things:

1) Flavours which contrast each other: sour/sweet, salty/sweet, fatty/acidic. The list goes on.

2) Flavours which complement each other (more below).

3) And the gestalt; flavours which both contrast and complement, as with the coffee/chocolate example.

Finding contrasting flavours is relatively simple. But note that you are not looking for diametric opposites, necessarily; the bitterness of asparagus is unlikely to pair nicely with the sweetness of caramel, for example. Which is why you really aim for the gestalt.

Finding complementary flavours, I think, is more difficult. In my view, what you are looking for is a flavour note that is common amongst two or more ingredients, while ensuring that none of the ingredients has wildly clashing notes.

Consider these three ingredients:

Turkey Cranberries Chocolate

The first two go together by way of contrast. Ditto the last two. And turkey with (unsweetened) chocolate would work very well–think about a mole sauce. But all three would (probably) not work well together without a lot of very careful finessing. There’s a theory about any three ingredients, but I can't remember the link.

end copypasta

To bring it to more quantifiable terms, McGee explores a lot about flavour pairing in On Food and Cooking, paying specific attention to volatile compounds which work well together. In many cases, it seems, foods which share compounds go well together; this is how Blumenthal put cauliflower and cocoa together, as they share a dominant compound (I cannot remember what it is). So there's that, when we're talking about aromas. My copy of McGee is currently with a friend, otherwise I'd cite you chapter and verse.

In terms of the five basic (primary) flavours you were talking about, I think it comes down to balance. Sweet is a flavour we are hardwired to seek out, as it promises high caloric input, a useful feature thousands of years ago. And the flavour of 'sweet' seems to balance out any other primary flavour; too sour? balance with sugar. Too salty? add sugar. Too bitter? add sugar. Umami itself seems to provide balance in many cases, and pairs especially well with salt (unsurprising given that MSG is a salt itself).

I'd really like to map flavours based on the primary/secondary/tertiary classification you've mentioned, and then look at popular pairings based on those characteristics.

No one really knows why certain flavors go well together. There are many theories having to do with sharing components, balancing, or tradition. Flavor is really a combination of taste (what your tongue senses) and aroma (what your olfactory epithelium way inside your nose sense). Recipes with two or more tastes in combination are common, but tastes need to be well balanced. Too bitter or too salty and the dish may be inedible. The aroma part is a bit harder.

Aroma comes from the many small molecules – the volatiles – found in food. With over 1000 odor receptors helping our brain distinguish between the safe and the dangerous, the good from the plain, coming up with a good theory for aroma combination has been hard. François Benzi from Firmenich, suggested at one of the Erice molecular gastronomy conferences (probably prompted by Heston Blumenthal) that if two food items share many detectable volatiles, then they should pair well together. This theory is the basis of the combinations you find at the FoodPairing web site. The theory is not the full story.

Humans are reluctant omnivores. Trying new food items once meant being prepared to endure unpleasant consequences, a lesson now imprinted in our brains. It takes us about two weeks of having the same thing to start liking it. The risk avoidance and the slow adoption lead to cuisines adopting a limited set of ingredients, often items that grow nearby. Over time, well tested imports finds their way into the mix, but over all they have been so stable that Elisabeth Rozin (married to Paul Rozin) introduced The Flavor Principle, an enumeration of the ingredients that give a cuisine its characteristic flavor.

Creating new flavor combinations requires balancing the traditional with a hint of novelty. In trying to learn to cook I have found that I can end up with a well appreciated dish if I concentrate on getting the taste right and use fresh ingredients (they are full of volatiles). To go beyond that requires talent and if it happens in a dish I enjoy my good luck.