How to make the ultimate Christmas turkey leftover sandwich, according to science
Easily upgrade your leftover lunch with some simple scientific tips from Dr Stuart Farrimond.
After a typically indulgent Christmas dinner, you’re usually left with a mountain of meat, stuffing, roast potatoes and the half-dozen pigs-in-blankets that not even Uncle Carl could squeeze in. Casting all this in the bin would be a profound waste and an environmental travesty: 1kg of food waste in a landfill produces the equivalent of 2.5kg of carbon dioxide emissions. There’s only one thing for it: all those leftovers need to be eaten!
Enter the Christmas leftovers sandwich…
You can forget the simple ‘leftovers crammed between slices of white bread’ recipe of yesterday, though. Nowadays, the ‘Christmas sandwich’ is the stuff of hipster coffee bars, delicatessens, supermarkets and corner shops alike. You can all too easily find yourself agonising over an endless choice of artisanal sandwiches, paninis and wraps loaded with prime turkey, organic sage and onion stuffing, and sickly-sweet cranberry sauce. There’s even an annual Christmas sandwich festival in London, where top chefs showcase their best offerings.
But in these belt-tightening times, it’s reassuring to know that with a bit of food science, you too can turn what was once pauper’s fare into a feast to rival the high street’s finest offerings.
Choose your bread
The first critical decision when you’re constructing the ultimate Christmas leftovers sandwich, is the bread. And the trick is to keep it simple. You can shun the crusty bloomers and posh brioche – the filling is the star of the show here.
My previous research has found that bread should be high quality but primarily serve as a soft, neutral vehicle for what’s inside. The total thickness of the bread should be about the same as that of the filling.
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Butter is more important than you might think
To each slice add a generous 1-2mm smearing of butter, which excites fat receptors in the mouth and enhances flavour, but also provides a waterproof layer to protect the bread from any liquid seepage and unpleasant sogginess from the filling.
Butter (which is more flavourful than margarine) allows flavour compounds to better disperse throughout and release their aromas, thus boosting the sandwich’s overall enjoyment factor.
The perfect size for the perfect sandwich
Always avoid the temptation to shoehorn as much as possible between those two slices. For maximum enjoyment, my research has shown that the total height of the sandwich should comfortably fit in the mouth, which works out at between 4.5cm and 5cm for most people’s chops.
Add the turkey
Turkey is the centrepiece of the classic Christmas sandwich, which presents a challenge because it’s perhaps the blandest meat going. Few people realise that turkeys are actually game birds, which have succulent and tasty meat – a far cry from today’s oversized broiler birds that are bred for lean bulk rather than fat and flavour.
A broiler turkey’s unexercised muscle and absence of fat reserves creates the perception of dryness and blandness.
Creating the perfect balance
As well as a goodly portion of fat (from the butter, if not the bird), a great sandwich relies on a balance of the basic tastes: sweetness, saltiness, sourness and umami. A steady hand is needed when applying the cranberry sauce – too much and it’s game over.
When the overall sweetness of each mouthful exceeds the equivalent of a 9 per cent sugar solution, food becomes sickly and unappealing. Stuffing is a must as it adds a little sweetness but also, and more importantly, gives much-needed depth – its sage and onion aromas waft up the back of the throat and into the nasal cavity, where it’s experienced as a burst of herby flavour.
Generally speaking, the more mouth sensations that are experienced with every bite, the more enjoyable the food is.
Don't forget seasoning
A good grind of pepper will give some pungent heat to titillate the mouth – the irritating chemical in black pepper, called piperine, stimulates hot-pain nerve fibres in the same way chilli does to create the illusion of heat.
If you’re feeling adventurous, add some leftover bacon for crunch and texture, an extra hit of saltiness and a powerful kick of umami – the savoury ‘meaty’ taste that makes soy sauce, Parmesan and cured meats so irresistible.
If you don’t use bacon and use unsalted butter, then season the meat with a sprinkle of salt. This amplifies all the flavours and boosts sweetness perception.
How many fillings should you include?
Forget all the trendy extras like Brie, chorizo, cabbage slaw and mayo. Research shows that a sandwich’s deliciousness and structural integrity plummets when you have over four fillings (3.6 being the optimum if that were possible!).
Serve with a side of salad for some freshness and much-needed healthfulness. Following the rules above, select your favourite ingredients and whatever you do, don’t subject your family to the bland turkey horror that marred my youth.
Final note: I recommend buying a heritage breed bird that has been bred to high welfare standards, if you want to discover real turkey flavour.