Spaghetti

Spaghetti is dried pasta made from durum wheat semolina and water, extruded as a solid round strand and cut to a standard 25-26cm. The usual gauge sits between 1.7 and 2.0mm: Barilla's no. 5 is 1.75mm, De Cecco's no. 12 is 1.9mm. Those numbers are not an industry standard: each factory has its own scale, so one brand's no. 5 can be thicker than another's no. 7. Read the millimetres, ignore the number.

The name is the diminutive of spago, string. Before the nineteenth century the shape was called vermicelli, and in southern Italy it still is; when northern factories standardised their catalogues, spaghetti won and vermicelli slid sideways to mean a slightly thicker gauge.

What matters is the cross-section. A round solid strand has little surface per unit of weight compared with a ridged short shape, but an enormous number of strand-on-strand contact points. So the sauces that work are the ones that form a continuous film binding the tangle: an emulsion of oil and starch, a bond of egg and cheese, a finely passed tomato. A chunky meat ragù or a sauce of diced vegetables has nothing to grip and ends up at the bottom of the bowl with bare pasta on top. That is not tradition talking. It is geometry: the shape is engineering for the sauce.

Good spaghetti tastes distinctly of wheat: nutty, faintly sweet, occasionally like fresh toast. Bad spaghetti tastes of almost nothing and functions as a delivery system for whatever is on it. The difference is not the brand's marketing but the drying: slow-dried pasta keeps volatile aromatics that a four-hour, 95-degree industrial dryer burns off.

Texture is where the real argument happens. Properly cooked, the strand should offer resistance without being hard, and a cut cross-section should still show a faint chalky dot at the centre. Bronze-die pasta feels rougher on the tongue and holds a visible film of sauce; Teflon-die pasta feels slick, and the sauce beads off into a pool. One diagnostic: if the water turns thick and cloudy within five minutes, the pasta is shedding starch into the pot rather than saving it for the pan.

Four quarts of water per pound, salted once it boils, about a tablespoon and a half of coarse salt. No oil in the water: it floats, never touches the pasta and only helps the sauce slide off later. Do not break the strands; drop them in whole and push them under as they soften.

Now the part almost no box explains. The printed cook time assumes water boiling at sea level, at 100°C. At 1,000 metres water boils at roughly 96.7°C, at 2,000 metres at 93°C, and starch gelatinises proportionally more slowly, so you need one to three extra minutes. If you cook in Denver, Mexico City or the Alps and the pasta is raw on the timer, the pasta is fine and the physics is not.

And 'al dente' is not a preference. It is a state of the starch. As the strand cooks, water moves inward and the granules gelatinise along a front advancing towards the centre; al dente means that front has not yet reached the core, which is the chalky white dot you see in a cut strand. At that moment the gluten network is intact, the strand survives being tossed in a pan, and it releases amylose into the sauce where it belongs. Past that point the network fails, the starch leaves into the water instead, and you get pasta that is gluey outside and slack inside. It is also why al dente pasta has a lower glycemic index.

So: drain two minutes short of the box time, finish in the pan with a ladle of pasta water, and move the pan rather than stirring. That last two minutes is where the dish is made.

Use it for sauces that form a film: aglio e olio, where the emulsion is the entire dish; vongole, where clam liquor and pasta starch make the cream; finely passed tomato with basil; carbonara, off the heat before the eggs go in. Regional exceptions worth knowing are spaghetti alla Nerano with fried courgettes and provolone del Monaco, spaghetti all'assassina from Bari cooked risotto-style until the strands char, and spaghetti with colatura di alici from Cetara: oil, anchovy sauce, garlic, parsley, nothing to hide behind.

Unopened, dried spaghetti wants a cupboard that is cool, dark and above all dry, and the best-before date printed by the producer is the reference point; it is normally set two to three years from packaging. The fridge is the wrong place for it because it is humid. Once the bag is open, move what is left into an airtight jar or clip the bag closed, because semolina takes moisture from the air: pasta that has picked up humidity cooks softer, loses its bite sooner and can develop hairline cracks along the strands.

Over long storage the small amount of fat in the wheat germ oxidises and the smell shifts from faintly sweet to flat and papery; wholemeal spaghetti, which keeps more of the germ, gets there in months rather than years. Cooked spaghetti behaves differently: in a lidded container in the fridge it keeps two or three days, going firmer and drier as the starch retrogrades, and any sauce on it keeps being absorbed, so it softens where it is wet and stiffens where it is not.

Turn the packet over first. The ingredient list should read durum wheat semolina and water, nothing else. Then look at the strands through the window: bronze-die pasta (trafilata al bronzo) is pale straw rather than golden, matte, faintly chalky, with visible flour dust in the bag and a slightly rough surface. Teflon-extruded pasta is smooth, glassy and a deeper uniform yellow. Slow drying at low temperature is usually stated on the pack in hours; industrial pasta is dried in eight to twelve, artisan in twenty-four to fifty.

What gets confused with it on the shelf: spaghettini, vermicelli and capellini are thinner, bucatini are hollow, and brand numbering is not standard, so read the millimetre gauge rather than the number. Fresh egg spaghetti and spaghetti alla chitarra are a different product entirely. Whole wheat and gluten-free versions sit in the same bags. Price is a fair signal here: supermarket own-brand runs about £1 or $1.50 for 500g, while Gragnano IGP and named artisan mills run $5 to $9 or £3 to £6 for the same weight.

In the US, Barilla and De Cecco are in every supermarket at $1.50 to $3 a pound and make a perfectly good dinner. The meaningful step up is Rummo, Garofalo and Mancini at $4 to $6. Bronze-cut Gragnano IGP and small artisan producers (Faella, Setaro, Gentile, Afeltra, Martelli, Verrigni, Rustichella d'Abruzzo) run $7 to $14 a pound at Eataly, Gustiamo, Market Hall Foods and Amazon.

In the UK, Waitrose, Ocado and Sainsbury's stock De Cecco and Garofalo at £2 to £4.50 per 500g, which is £4 to £9 per kilo; Natoora, Vorrei, Vallebona and Seggiano ship bronze-cut Gragnano nationwide at £8 to £18 per kilo. In Italy the same artisan pasta costs €6 to €14 per kilo and supermarket brands €1 to €2.20.

Check the pack in this order: 'trafilata al bronzo' or 'bronze cut'; a slow-drying claim with hours and temperature stated; protein content, where under 12.5% predicts a strand that goes slack; and the IGP mark if you want Gragnano specifically. Pale and matte is right, glossy and bright yellow is not, and semolina dust in the bag is a good sign rather than a defect.

Gragnano, half an hour from Naples, is the pilgrimage. The historic factories along Via Roma, a street deliberately aligned with the wind that once dried the pasta in the open air, run tours and sell direct, and the town holds a pasta festival in September. Torre Annunziata, a few kilometres away, shares the same history and the same wind.

In Naples, spaghetti alle vongole belongs to Borgo Marinari and Santa Lucia, on the water. In Cetara on the Amalfi Coast, colatura di alici is the local anchovy sauce and spaghetti is the only dish that carries it properly. In Nerano, a hamlet of Massa Lubrense, the courgette-and-provolone version carries the village's name.

Bari does the heretical one: spaghetti all'assassina, cooked dry in the pan like risotto until the strands scorch. Rome is where spaghetti meets carbonara, gricia and cacio e pepe, in the trattorie of Testaccio and Pigneto, whether carbonara belongs on spaghetti or rigatoni is a live local dispute with no resolution in sight.