Last year wholesaler Booker created a media furore by announcing that it was to start supplying sandwiches with a 14-day shelf-life to convenience stores and foodservice outlets.
The secret was to use oatmeal bread, mix all fillings with a slightly acidic mayonnaise, do away with salad and flush the packs with carbon dioxide and nitrogen.
On the continent consumers wouldn't bat an eyelid about the prospect of a two-week old sandwich. As Jim Winship, director of the British Sandwich Association, points out: "In Europe, they sell sandwiches with a 30-day shelf-life."
In the UK, though, bloggers, tweeters and food columnists were up in arms, outraged that consumers might be unwittingly buying what in their opinion were miserable creations that served only to maximise profits for retailers and manufacturers.
This British obsession with freshness and suspicion of packaging technologies probably explains why most sandwich producers stick to a much shorter shelf-life, even if the cost is more frequent deliveries.
Tanya Everest-Ring is marketing manager with Raynor Foods, a Chelmsford-based sandwich maker whose motto, fittingly, is 'we cut sandwiches ... not corners'.
"We could improve the shelf-life by modifying the atmosphere of our sandwich packs, but we don't," she says. "Consumers don't want to buy a sandwich that has been sat on the shelf for six days. They know a lot about sandwiches as they make them at home and they know that a sandwich made five days ago won't be fresh."
To ensure its sandwiches are always fresh when they reach consumers, at Raynor Foods, bread is delivered daily at 2am and sandwiches are made throughout the day. "We also use the highest quality packaging we can get to give a three-day shelf-life," says Everest-Ring.
All of Raynor Foods' customers are within a 100-mile radius, enabling sandwiches made the previous day to be delivered early each morning via the firm's own fleet of vehicles.
"If we started supplying companies further afield, we would lose the flexibility our customers value and which means we can replenish them, if, say, they have a power-cut," says Everest-Ring.
Adelie, the parent company of Food Partners and Buckingham Foods, has a similar view on sandwich shelf-life. "Extending shelf-life slightly would certainly help to manage waste more effectively and there have been some very interesting packaging developments over recent years," admits chief executive Chris Thomas.
"However," he concedes, "there is a fine balance to be struck as we know that food-to-go consumers are looking for freshness and could well be 'switched off' if we pushed the shelf-life out too far."
Like Raynor Foods, Adelie ensures sandwiches are as fresh as possible when they reach customers via daily deliveries using its own fleet of vehicles, and in Adelie's case, delivery spans a far wider geographical area.
"Because we have our own fleet of over 200 vans across our nationwide chilled distribution network we are able to make deliveries to our customers on a daily basis, seven days a week," explains Thomas. "The vast majority of our deliveries are made between 10pm and 7am in the morning, ensuring our customers are able to keep the chiller cabinet fully stocked during the key breakfast and lunchtime trading periods."
Consumer prejudice isn't the only argument against deploying modified atmosphere packaging (MAP). There are also some technical issues in terms of its effect on certain ingredients. Most consumers take freshness cues from a slice of tomato or a leaf of lettuce. While meat, cheese and bread are effectively 'dead', produce is still 'alive', or at least respiring. It needs the oxygen that MAP removes or else it will wilt, which is why produce packaging uses a permeable micro-perforated film to allow the exchange of gases. Meats, breads and other non-respiring ingredients need barrier films, which are not permeable.
While MAP can increase shelf-life by as much as 30 days, it seems the key to success lies in a short not a long shelf-life consumers want freshly made sandwiches. And that's not all they want.
Packaged sandwiches have been around since the 1980s, and in that time they have evolved from a lunchtime product into a 'grab and go' snack for any time of day. Hand in hand with this trend has been the expansion of the market to include products like sushi, wraps and portable breakfast cereal pots.
Explaining how Tesco has adapted to 'all day demand', a spokeswoman said : "At Tesco we always want to make sure our customers can buy what they want, when and how they want it. Many of our customers are busy and want high quality, good value food on the go, which we've already been providing for decades with our sandwiches, salads and ready meals."
More recently, the spokeswoman said Tesco had looked at new ways of giving customers a whole array of on-the-go products throughout the day and had introduced a trial of its Food to Go concept in two stores.
"Food to Go offers customers in Chester and Sandhurst breakfast options like porridge in the morning, sandwiches and sushi at lunch time and ready meals and hot chickens in the evening," said the spokeswoman.
Tesco and the other multiples might be taking all the glory for delivering what the consumer wants sandwiches throughout the day and a greater variety of 'grab and go' products but behind the scenes, it is the supply chain that is making that happen; from sandwich producers to distribution providers and packaging suppliers.
At Raynor Foods, for example, these changes in consumer demands have been met through new product development. "We've increased our offering of breakfast and 'man' sandwiches such as bacon and egg, as well as tortilla wraps, which have become more popular, perhaps because they are very tightly bound so easy to eat on the go without dropping," says Everest-Ring.
NFT claims to be the UK market leader in chilled food and drink distribution and is responsible for the distribution of Greencore's sandwiches to Marks & Spencer. The contract requires Greencore to produce on average 250,000 units daily for delivery to depot.
This presents a significant logistical challenge: to provide a cost-effective and reliable method of collecting and delivering substantial volumes of time-critical sandwiches on the same day, often within a 12-hour window.
With such high-volume turnover, Greencore has a tight daily operational schedule, which means it needs a logistics partner with the vehicle availability and systems capability to perform consistently and reliably.
"Pre-packed sandwiches are one of the most time-critical products in a supermarket. It's imperative we ensure the vehicles arrive on time at Greencore's depot and then when loaded, reach the retailer within the 15-minute booking window set," says Dale Fiddy, sales and marketing director at NFT.
"We have the networks in place to overcome any challenges, such as bad weather, and we keep our customers informed of progress for efficient forward planning. We run a completely transparent operation that gives manufacturers and retailers complete visibility of their order, from when it is picked in the depot, during transit, and when the delivery is received and ready to invoice,"
NFT also custom-built a chilled double-deck trailer to provide Greencore with the most cost-effective way of delivering to depot. Each trailer is capable of handling a third more sandwiches on each journey, which means that Greencore is able to despatch product more quickly, freeing up space in its holding area.
The holding area isn't the only part of the factory where sandwich producers are looking to free up space.
According to Kevin Curran, director of Tri-Star Packaging, sandwich producers are adopting a Just-In-Time (JIT) approach to production, and consequently pressurising their suppliers to hold more stock to maximise production space.
"Sandwich producers are pushing pressure back up the supply chain and making it tougher for suppliers like us as we have to take on more space to hold stock," he says. "Instead of a weekly delivery of, say, 100,000 sandwich packs, we are having to do two deliveries of 50,000 packs."
What's more, sandwich packs are no longer limited to triangular wedges.
"Bloomer bread is quite trendy at the moment," says Curran. Tri-Star has created its Artisan range specifically for these more rustic style sandwiches. "By making sandwiches on bloomer bread and packing them in an Artisan bag, retailers find they can charge twice as much as they would for a standard triangular sandwich."
Curran says the expansion of the grab and go market has also fuelled demand for packaging to accommodate a variety of products.
Innovations from Tri-Star have included the Deli-Topper: a two-piece plastic pot for keeping two components separate until the point of consumption. Possible uses could be for crudités and hummus or salad and croutons.
In August, Tri-Star launched the Nibble Box: a range of compartmentalised boxes for holding anything from pasta to tapas or tortilla wraps.
"Compartmentalised trays seem to be gaining ground," notes Curran.