‘Many of the sensations of good food come from low-level bitter polyphenol compounds...’

In practice, most of these things are encountered in dilute form, which means they are tolerable. In fact, in the proper concentrations, they can be tasty. Many of the sensations of good food come from low-level bitter polyphenol compounds tickling your taste buds just enough.

The warm mouthfeel of red wine is a restrained bitterness, as is the mild astringency of tea (why many people have it with milk), both of which are polyphenols called tannins. Try drinking olive oil straight. It will create a bitter note at the very back of your throat (the polyphenol is oleocanthal, and it blocks inflammation as effectively as ibuprofen).

Items that might not be eaten uncooked, such as garlic, are likely to be good nutraceutical vectors, as are things only eaten in small amounts. Pepper and chillies are obvious, but so are herbs and spices, which would be overwhelming if concentrated, but, used correctly, they form the backbone of hearty eating.

The yellow spice turmeric, the base of a curry, is one of the best-known nutraceuticals and one of the first options people turn to when they want to add a nutraceutical kick to their intake. Pomegranate is another standout. But the richest part is the fibrous skin, which is too bitter to eat (and the reason juice, which draws from the skin as well as the palatable interior, is a tastier option).

Fruit seems different, as it is an excellent example of the whole concept, particularly anthocyanins in purple berries and resveratrol in grapes. But fruit is sweet (the bitterness in red wine mentioned above comes from seeds and stems left in the fermenting juice).

The answer is that fruit is only sweet when it is ripe, and the plant wants you to eat it (fruit is nature’s way of getting seeds dispersed via the bowel of an animal). When it is young and green (and the plant isn’t ready for you), it is sour. Ripening breaks up some of the healthy and repellent molecules, but by no means all. It principally overlays them with sugar — much like a chocolate bar. Anyone who has tried the dark varieties of chocolate, which are high in healthful polyphenol cocoa solids, understands how bitter chocolate can be. Sugar makes it edible.

The necessary implication here is that most useful nutraceutical options, if they can’t be masked by sugar, have to be processed. That is one of the imperatives behind cooking — moderating overwhelming flavours. Commercial processes do the same. Pomegranate juice is pasteurized for shelf life, which kills a lot of the goodness, but shelf life is not the only consideration. It would be undrinkable otherwise.

Cacao beans are piled under their trees to ferment before starting the road to becoming a chocolate bar (sugar alone doesn’t do it). Tea is heated to break down the tannins. Coffee is roasted.

These steps cost a lot in healthful molecules, but the price has to be paid. Even enthusiasts won’t hold their noses for too long. Fortunately, sensible processing still leaves plenty of goodness to be absorbed. And plenty of options to discuss next time.