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Polpettone di Tonno
The no-bake tuna loaf that meant summer was here

No oven, no heat, made the day before and kept cold. My mother made this when the Campanian summer made cooking impossible. We ate it at the table and sometimes carried it to the beach in paper.

Polpettone Tonno

It has been roughly forty years since I last had this dish the way my mother made it, which puts it somewhere in the mid-1980s. She made it in summer, when July and August in Caserta meant a heat that made turning on the oven a serious commitment, and the kitchen already retained enough warmth from the previous day. The polpettone di tonno required no oven at all. It was cooked by boiling, which sounds strange for something called a loaf, but which produced a result that was firm, sliceable, and entirely suited to being eaten cold. You boiled it, you let it cool, you put it in the refrigerator overnight, and the next day it was ready.

My father did not eat this. Fish was not his category, and a cold tuna loaf would have confirmed everything he suspected about seafood. On nights when she made polpettone di tonno, he would have pasta with tomato, or something simple from what was in the kitchen. The rest of us ate the tuna loaf with mayonnaise and lemon, sometimes with a salad of green beans and tomatoes from the garden. There was something about the combination of cold tuna, the slight brininess of capers, the olives cut into the mixture, and the mayonnaise that worked very specifically in summer heat. Nothing about it would be improved by warmth.

The beach version was even simpler. My mother would wrap the slices in wax paper, pack them into the bag with everything else, and they survived the drive to the coast and the first hours on the beach without any trouble. A thermos bag if we were organized. Paper napkins, a lemon wedge in a small container. Eating cold polpettone di tonno on the beach with sand on your hands is one of the more specific sensory memories I have of those summers.

She wrapped the loaf in baking paper and twisted the ends closed the way you close a candy. That was how it held its shape while it boiled. When you unwrapped it cold the next morning it came out perfectly cylindrical and you sliced it like bread.

The technique is not complicated but it is specific. You combine mashed potato with well-drained canned tuna, eggs, Parmigiano, breadcrumbs, capers, black olives, and parsley. You mix it to a cohesive mass, shape it into a cylinder on a sheet of baking paper, wrap it tightly — twisting the ends like a large candy wrapper — and tie it with kitchen string. Then you lower it into a pot of cold water, bring it to a boil, and cook it at a steady but gentle simmer for thirty to forty minutes. The potato in the mixture gives it the starchy structure that holds together without drying out; the egg binds; the rest provides the flavor. You cool it completely before refrigerating, and you never slice it warm. Warm, it falls apart. Cold, it is its own thing entirely.

I have been trying to reconstruct this from memory and from the infographic below, which captures the preparation more faithfully than I could have on my own. The details I remember clearly: the capers had to be desalted and dried, the tuna had to be the kind in olive oil and properly drained or the mixture would be too wet, and my mother always added a small amount of grated lemon zest that I have not seen in other versions but that made it smell unmistakably of summer. I am not certain I have fully replicated her version since. I am getting close.

Why boiling keeps a tuna loaf moist — and what the potato actually does

Cooking the loaf by boiling rather than baking keeps it surrounded by water vapor and liquid the entire time, which means moisture can only flow into the loaf, not out of it. Baking in a dry oven works the opposite way: the surface loses moisture rapidly, which is useful when you want a crust but counterproductive when you want a moist, sliceable cold preparation. The boiling method produces a texture closer to a terrine than to a meatloaf — firm but not dry, with a clean cross-section when sliced cold. The potato performs a specific structural role here. Mashed potato contains high levels of amylose and amylopectin — the two forms of starch that make up cooked potato's matrix. When the loaf cools, these starches retrograde (recrystallize), creating a firmer gel structure that holds the loaf together at refrigerator temperature. This is why cold polpettone slices cleanly and warm polpettone does not — the starch structure is only fully set once cold. The egg proteins contribute additional binding through coagulation during cooking, but the potato is the structural foundation. The canned tuna in olive oil adds fat-soluble aroma compounds — primarily aldehydes and esters from the fish oil — that are what gives this dish its specific cold summer character: savory, slightly briny, with that particular sweetness of good tuna in oil.


The recipe

Polpettone di tonno napoletano -- the no-bake tuna loaf from Naples, step by step
Polpettone di tonno napoletano — boiled in paper, sliced cold, served with mayonnaise and lemon — click to enlarge.
300 g, well drainedCanned tuna in olive oil
400 g, boiled and mashedFloury potatoes
2, wholeEggs
3 tbsp, gratedParmigiano Reggiano
3–4 tbspFine breadcrumbs
a handful, pitted and slicedBlack olives
2 tbsp, desalted and driedCapers
a handful, choppedFresh flat-leaf parsley
optional, half a lemonLemon zest
to tasteSalt, black pepper, olive oil
to serveMayonnaise and lemon wedges
1
Boil the potatoes whole in salted water until completely tender. Peel while warm and mash thoroughly — no lumps. Let cool slightly but work the mixture while the potato is still warm enough to be pliable.
Floury varieties (like russet or a dry yellow potato) produce a firmer result. Waxy potatoes make the mixture too sticky.
2
Drain the tuna very well — press it against the strainer. Flake it into a large bowl. Add the mashed potato, eggs, Parmigiano, breadcrumbs, olives, capers, parsley, and lemon zest if using. Season with salt and pepper. Mix until cohesive.
The mixture should hold its shape when pressed. If it feels too wet, add another tablespoon of breadcrumbs. If too dry, a small drizzle of olive oil.
3
Lay a large sheet of baking paper on the counter. Transfer the mixture onto it. Shape it into a cylinder roughly 20–22 cm long and 8 cm in diameter using your hands. Press firmly so it holds together.
4
Roll the cylinder up in the baking paper, then twist both ends tightly like a large candy wrapper. Tie each end with kitchen string. For extra security, wrap again in a second sheet of paper or in plastic wrap before the final string tie.
The tighter the wrap, the better the shape. Any loose sections will expand unevenly during boiling.
5
Place the wrapped loaf in a pot large enough to hold it flat. Cover with cold water. Bring to a boil, then reduce to a steady medium simmer and cook for 30–40 minutes, turning once halfway through if the loaf floats.
6
Lift the loaf out carefully. Let it cool to room temperature without unwrapping. Then refrigerate for at least 3–4 hours, or overnight. Slice cold, 1.5–2 cm thick, and serve with mayonnaise and lemon.
Do not attempt to slice warm. The loaf is only properly set once cold, and it slices cleanly then.

How to serve it

At the table, cold
Sliced thick with mayonnaise on the side, a few lemon wedges, and a salad of green beans and tomatoes. This is the full version. Nothing else needed.
At the beach
Wrapped slices in wax paper, kept in a cool bag. Eat with bread, a lemon wedge, and whatever else is in the picnic. It holds for hours without losing anything.
In a panino
A thick slice between two pieces of rosetta or a crusty roll, with a smear of mayonnaise and a few leaves of lettuce. One of the better summer sandwiches.
Made the night before
This is not a compromise — it is the correct version. The overnight refrigeration improves the texture and lets the flavors settle. It is always better on day two.

My father never ate this, which meant there was always more for the rest of us. I remember that as a fact without any complaint attached to it. He had his pasta with tomato, we had the tuna loaf with mayonnaise, and that was summer dinner in Caserta in July. I have been making it for my daughters and getting close to the right result. The lemon zest is the detail I am most sure about. Everything else I am reconstructing from memory and from the smell when the paper wrapping comes off a cold loaf the next morning — which is its own kind of specific and recognizable thing.

Buon appetito — e portalo in spiaggia.

More from the collection
Insalata di riso
The other great Italian summer cold dish -- rice salad with everything in the refrigerator.
Insalata di patate e fagiolini
The salad that goes alongside -- green beans, potato, tomato, olive oil.