Starbucks Signature Tuna Melt Panini

The Starbucks Signature Tuna Melt Panini costs £7.10 and carries 481 calories with 28g of protein and 6g of saturated fat. Flaked tuna with Cheddar, mozzarella, red pepper and red onion in a stone baked ciabatta with sourdough.

6g of saturated fat is the lowest of the four hot signature items, well under the grilled cheese toastie at 9.6g and the ham and cheese toastie at 9.1g, despite carrying two cheeses of its own. Tuna is an unusually lean protein and it displaces cheese that would otherwise have to carry the filling.

Total fat at 13g is also the lowest of the hot items, and the 28g of protein matches the ham toastie exactly. That combination makes it the best protein to fat ratio in the sandwich category, which is not the reputation a melt usually has.

Fibre is the weak figure at 2g, the lowest of any sandwich on the menu. Ciabatta made with white flour carries very little, and there is no salad in this one to make up the difference. Salt at 1.5g is mid range, and carbohydrate at 62g is the second highest in the category.

A tuna melt divides people more than anything else in the case, and the reason is temperature rather than flavour. Cold tuna mayonnaise is familiar; heated, the mayonnaise loosens and the fish firms, which produces something quite unlike the sandwich version. Anyone who has only had tuna cold should expect a different food rather than a warm version of the same one.

Fish is the allergen that matters here and it sits alongside egg, wheat, mustard, rye and milk. No dietary labels apply. Prices reach £7.90 on delivery, which makes it one of the two most expensive sandwiches. The tomato and mozzarella panini is the vegetarian option at the same price with 30g of protein.