Chemical Canvas

There are three reliable ways to become intolerable at dinner: ask for the wine list before sitting down, enquire after the coffee’s processing method, and hold a square of chocolate to the light as if expecting a watermark. Each announces a person whose pleasure has acquired paperwork. I confess my sympathies lie with the intolerable.

On their table, wine arrives with a château, coffee with an altitude, and chocolate with a cacao percentage set in type large enough to be legible from a neighbouring tax bracket. Acidity becomes praise, fermentation small talk, and water a subject on which sensible people develop indefensible positions. I have let coffee cool because it had more to say at thirty-five degrees, an act of patience unavailable to several people I love.

Members of this sensory minor aristocracy recognise one another by the pause. A wine drinker, a coffee obsessive and a serious eater of chocolate hold the substance in the mouth, allow it to change, search for a fruit absent from the ingredients, attach a word, offer the word to the table. At some point one of them says cherry; the others lean in, and the host begins to regret dessert.

The anthropologist Susan Terrio underwent the formal initiation in Robert Linxe’s Saint-Honoré boutique. A silver tray arrived carrying four dark bonbons, two milk ones and a bottle of cool water. Linxe announced the tasting as an apprenticeship, instructed her to let each piece melt slowly, then left to take an important telephone call. Terrio remained alone with the chocolates and the knowledge that she was being examined. Her palms began to sweat.

When Linxe returned, he asked which chocolate she preferred and why. Terrio chose the first dark ganache, a house speciality called the Quito. He congratulated her judgement, then explained that a person who knew how to judge wine could judge chocolate: length on the palate, body, acidity, bouquet, finish. He had served chocolate and marked the paper in wine[1].

Chocolate had entered the cellar and immediately asked to see the guest list.

Coffee, chocolate and wine are dense mixtures of many compounds. Each is a chemical canvas, prepared and textured enough to invite several readings. Processing marks it; the taster brings attention, language and the occasional inherited prejudice.

Chemically, each is a crowd. Analytical instruments can record dozens to hundreds of volatile compounds, depending on the product, sample and method used to examine it. Concentration, threshold and ratio determine which compounds reach perception. A survey of food aroma research found roughly 230 recurring key food odorants among some ten thousand known food volatiles. Individual foods drew their characteristic patterns from groups of three to forty compounds[2]. The specialist term is matrix, a word suggesting that lunch has acquired border control.

One recurring pigment is furaneol, whose name sounds like a municipal arts grant. Aroma studies have found it active in dark chocolate, in four commercial Arabica coffees and in a Marselan wine; assessors associate it with caramel and strawberry. In Muscat Bailey A grapes, a furaneol glucoside can release the free odorant during alcoholic fermentation. A single molecule arrives with three biographies, embedded in three matrices, surrounded by three sets of neighbours[3].

A prepared canvas has weave, ground and drag. Chemistry supplies these through concentration, volatility, solubility and threshold. Each matrix sets a new price for sensory admission[4]. Wine, having spent several centuries perfecting admission prices, was always going to understand.

The raw materials have already acquired long biographies. Grapes, coffee cherries and cacao pods carry variety, place, weather and harvest into processing. Microbes transform grape juice into wine, coffee fruit during post-harvest fermentation, and the pulp surrounding cacao beans. Coffee and cacao pass through heat, where roasting produces new aromatic compounds from precursors laid down earlier. Wine continues through fermentation, ageing, oxygen and, sometimes, toasted oak. Conching edits chocolate again, allowing volatile compounds to leave according to their physical properties[5].

By the time any of them reaches a table, it has endured a sequence of living organisms, controlled neglect and people charging for the story. The story is frequently excellent, which is how they get us.

This helps explain the ceremony. Wine is swirled. The crust on a cup of coffee is broken and inhaled. Chocolate is allowed to melt. Temperature, movement, fat, water and alcohol govern the release of volatile compounds, so the sensory picture changes through time. The experienced taster learns where to wait: coffee as it cools, wine as it opens, chocolate as it softens. Once an enthusiast acquires a notebook, ordinary swallowing becomes a reputational risk.

People who love these things can be exhausting in precisely the same way. They are happiest when pleasure has prerequisites.

Connoisseurship eventually requires a government. In the 1980s, Ann Noble and her colleagues gave it a circular form with a standardised vocabulary and aroma wheel for wine. The coffee world later produced a “living lexicon” of 110 attributes, each furnished with a definition, a physical reference and an intensity anchor. A chocolate study began with more than one hundred descriptors generated by consumers and organised a final wheel of 61 terms across appearance, aroma, texture and flavour[6].

A wheel turns an elusive smell into an object people can point at. The coffee lexicon calibrates woody with a Popsicle stick; blackberry arrives with jam; dark chocolate requires cocoa powder and a chocolate bar. Pleasure had acquired office supplies, reference standards and a procurement process.

The circles overlap before anyone prints them. Coffee’s lexicon contains winey, fermented, cocoa and dark chocolate. French chocolate connoisseurs borrowed body, acidity, bouquet and finish from wine. Wine supplied the hereditary titles; coffee and chocolate promptly created peerages of their own. A person moving among the three fields encounters familiar fruit, flowers, nuts, spices, smoke, leather and earth, followed by a new set of rules for deciding when each word has earned its place.

In 2016, Ilja Croijmans and Asifa Majid studied wine experts, coffee experts and regular consumers. Each expert group showed heightened awareness of odours in daily life. Wine expertise appeared in agreement and specific source terms for wine. Coffee expertise appeared in a source-based strategy for coffee. Across the groups, tasting followed the same sequence: inspect, smell, taste, name, compare[7]. Years of training had made sensation communicable and everyone slightly worse company.

A descriptor is a proposal carrying mild social pressure. When someone says cherry, the word sends everyone at the table back into the glass to search for the resemblance. The wheel supplies coordinates, repetition steadies them, and conversation lets the picture travel. The confident taster says Morello. The rest of the table updates its records.

Colour can lay down the first wash. In a famous experiment, fifty-four Bordeaux oenology students described a white wine coloured red with an odourless dye. The dyed wine recruited red-wine vocabulary into their accounts. The eye had prepared a field of possible objects before the odour received a name[8]. Colour had brought its own sommelier.

I recognise the mechanism. Once apricot is said, a small orange fruit begins filing its claim before I lift the glass.

The odourless dye, the word apricot and the wheel begin organising the chemical signal before anyone names it. Learned categories, visible cues and remembered objects decide which likenesses surface. A chemically crowded drink can sustain several faithful readings.

Kathryn LaTour and John Deighton took the canvas almost literally. After interviewing Master Sommeliers, they ran a series of studies with wine, coffee, chocolate and beer enthusiasts, asking how people learn to recognise complex tastes. Beginners worked with analytic grids; developing enthusiasts treated flavour as a temporal narrative and drew its shape[9]. Sensory science had exhausted the tasting grid and issued drawing paper.

In one experiment, 122 chocolate enthusiasts tasted an artisanal dark chocolate containing cranberries and almonds, then represented the experience as a “summary story”; a beer group completed a parallel task. The researchers pooled the groups for the recognition result. Across that analysis, visual narrative improved later recognition. Flavour now had a line on the page.

One Master Sommelier told the researchers that “everybody paints the lines differently,” with the serene confidence of a profession that can say lines over lunch and send an invoice. A tasting note gives the entry, the middle and the finish a shape another person can follow.

Odour is unusually gifted at opening old pictures. In studies of autobiographical memory, smells have called up earlier memories and a stronger sense of being carried back into them. A word such as blackberry can gather a calibrated reference, one unreproducible summer and the weather stored with it[10].

Wine people, coffee people and chocolate people have made the same peculiar agreement: they will keep looking at an invisible picture, preferably in company and at some expense. There are easier clubs to join, several with jackets.

At the end of the table, the coffee has cooled, the chocolate has softened and the wine has warmed. Someone says cherry. Three heads incline by a fraction. The host checks the label, which offers geography, alcohol and no practical assistance.

On the next exhalation, volatile compounds from the cooled coffee, softened chocolate and warmed wine take the same route behind the palate towards the olfactory epithelium[11]. Three elaborate cultures have built wheels, cellars, clubs and cupping laboratories around that short anatomical passage.