According to Waitrose, pre-packed sandwiches are more popular than ever with sales up 14 per cent compared to this time last year. While some of us frequently find ourselves hastily grabbing a sandwich from the chiller cabinet to eat on the hoof, others pick up their favourites on the way into work, leaving them stashed in backpacks until lunchtime comes calling.

But is there a noticeable difference in quality between a fridge-cold or room temperature sarnie?

Christabel Cairns, associate managing director of the Guild of Fine Food. says that temperature plays a crucial role in how food tastes: “For example, cheese is best eaten once it’s been out of the fridge for a short time. The same goes for charcuterie. In terms of fruit and vegetables, we keep them chilled to preserve them, but their natural habitat is ripening in the sun, so it follows that there is more flavour when at room temperature”.

While storing fresh food at a cool temperature (below 5C) is necessary to keep it safe for any extended period of time (over four hours) it can have a detrimental effect on the texture. Bread in particular becomes firmer, drier and less fluffy when chilled, though it will restore somewhat once returned to room temperature. As sandwiches are made up of different ingredients with a range of characteristics, deciding whether yours is best eaten chilled or at room temperature is not quite as straightforward as it sounds.

The taste test

We tasted five of the healthiest pre-packed sandwiches to discover at what temperature they were at their best. I began by sampling each one at a fridge-cold 4C, and then kept them wrapped at room temperature (19C in my kitchen) and tried them at 15-minute intervals noting the flavour and texture to establish the optimum time to eat each one.

Sainsbury’s Tuna Mayo

Optimum eating time: 15-30 minutes out of the fridge

Sainsbury's tuna mayo

This is a very simple sandwich made with oatmeal bread, skipjack tuna and mayonnaise. Straight from the fridge, it doesn’t taste of much. After 15 minutes, the creaminess of the mayo and the tuna flavour is more apparent as the sandwich warms up and the bread becomes less chewy. At 30 minutes, however, it starts to flop while the flavour remains pretty much the same. There’s no benefit in leaving this one out beyond half an hour.

Waitrose Classic BLT

Optimum eating time: 30 minutes out of the fridge

Waitrose Classic BLT

Sandwiches containing tomatoes always prove tricky. At cold temperatures, the tomato is tasteless. As it warms up, the flavour may improve slightly but the texture deteriorates, becoming soft and mushy which inevitably makes the bread soggy (though the layer of mayonnaise in this case adds some protection). I found that 30 minutes out of the fridge, once the flavours have fully developed but the sogginess is yet to set in, is the best time to enjoy a BLT.

Waitrose Roast Chicken Salad

Optimum eating time: 45 minutes out of the fridge

Waitrose Roast Chicken Salad

Straight from the fridge, it’s quite hard to detect the different flavours of the ingredients that are packed into this sandwich which include roast chicken breast, tomatoes, lettuce and cucumber. The flavours develop and the bread softens the longer this sandwich sits at room temperature making it much more enjoyable once it’s warmed up a little. And though it contains tomato, there’s only a small amount between the lettuce and chicken so it doesn’t result in soggy bread.

Boots Ham & Cheese

Optimum eating time: 30 minutes out of the fridge

Boots ham and cheese

This sandwich contains ham, cheese, pickle, lettuce and mayonnaise. Tasted straight from the fridge, the malted bread is surprisingly soft and the lettuce maintains some crunch but the cheese is hard and the only flavour comes from a slight twang of pickle. At 15 minutes the sandwich has developed a little more flavour but the lettuce is already starting to lose its crispness. Leaving it out for longer benefits the flavour and texture of the cheese but the oak smoked ham never really comes to the fore, even after 45 minutes.

Sainsbury’s Egg & Cress

Optimum eating time: 60 minutes out of the fridge

Sainsbury's Egg & Cress

A fridge-cold egg mayonnaise sandwich tastes very bland and unsatisfactory especially when compared to the soft and comforting qualities of the homemade version. After just 15 minutes out of the chiller, the mayonnaise regains some of its creaminess; at 30 minutes the bread recovers its bounce and the eggs shed their rubberiness (mostly). Of all the sandwiches tasted, the egg mayonnaise sandwich benefitted the most from being brought fully to room temperature.

The verdict

All the sandwiches improved in flavour and texture even after just a short while out of the fridge. In general, those containing salad needed less time so flavours could develop while retaining some crispness. Those with ingredients such as eggs and cheese tasted at their best when fully warmed up to room temperature. The edges of the bread dry out quickly so whatever temperature you plump for, be sure to keep the sandwiches air tight until you’re ready to eat.