Canned food has acquired a somewhat downmarket image in some grocery markets in latter years; not so in France. Peter Crosskey investigates a thriving industry in a market where even top chefs are staunch defenders of the humble can opener.

Not only have food industry professionals been displaying and sampling their wares at SIAL this week; France as a whole has been enjoying la Semaine du Goût (Taste Week). This is largely an educational exercise, during which food producers go into schools and do hands-on food preparation with children of all ages.

It also contains elements of generic promotion by food industry sectors. There is a hint of national pride in the French view of canned food, which was celebrated on 19 October during national canned food day (Journée Nationale de l'Appertisé - JNA).

Canned, bottled and pouch products which are cooked in a retort are referred to eponymously as produits appertisés after the 18th century inventor Nicolas Appert.

Having spent his youth working in his father's inn, Appert rose through the ranks of Napoleon's army as a successful quartermaster during the French Revolution. Appert's process of cooking food in hermetically sealed bottles allowed Napoleon to deploy an army in any season.

Today, French per capita consumption of appertised food is one kilo a week and household penetration is 99.7%. Over the past ten years, a stagnating EUR350bn (US$378bn) market has become a gently swelling EUR400bn market.

Positive public awareness has risen substantially over the same period, too, thanks to the promotional efforts of the Union Interprofessionel pour la Promotion des Industries de la Conserve Appertisée (UPPIA).

Like the rest of Europe, French consumers are buying more convenience foods: sales of ready meals and lunchbox products are growing steadily. Using metal bowls with secure easy-peel foil lids, French canners have developed a complete category of ready-to-eat salad recipes using rice, cous cous and pasta.

Last year they sold nearly 20,000 tonnes (filled product, net of packaging) of these products on the home market. The French interest is in the eating quality of the contents rather than the packaging.

Appertised products are regarded as a valid ingredient for cooking, from Michelin star chefs down to works canteens. "Appertised ingredients take nothing away from a chef's creativity," explains Bruno Léger, operations manager for contract caterer Carquefou, which delivers thousands of municipal meals for the city of Nantes.

"To ensure that everyone knows what we serve up, our website lists the menus and nutritional data for all our sites," he adds. His task as head of UPPIA's foodservice arm is simplified by detailed analysis of the nutritional profile of core canned foods.

This has been carried out by UPPIA over the past six years, under the watchful eye of Docteur Jean-Marie Bourre, head of research at the French national medical research institute INSERM. This year's target for the growing online nutritional database is 35 food products.

Canned foods made possible historic expeditions in hostile environments. It was the sight of an astronaut eating canned carrots on a space station which sparked a 21st century quest for the nutritional value of canned foods.

Researchers are discovering hidden treasures in the process. For instance, the appertisation process confers specific nutritional benefits to tomato products. These are now known to be the best bioavailable sources of the heart-friendly compound lycopene. This fat-soluble antioxidant is what gives ripe tomatoes their red colour.

The heat of the cooking process breaks down cell walls, making the lycopene digestible, while the can prevents oxidation or light damage for the life of the unopened product.

"The result is that the amount of available lycopene in canned tomato products is more than 60% higher than in fresh tomatoes," explains Bourre. He remains a strong advocate of diversity in food sources, however, to ensure nutritional balance.

A world authority on the omega-3 group of fatty acids, Bourre is deliberating over whether canned sardines deliver more omega-3 than mackerel in white wine for the latest revisions to the database. "There is some leakage of fat soluble omega-3 into the oil, while in white wine, the mackerel will retain these fatty acids in its flesh."

Both species of oily fish are rich sources of omega-3. The aim is to deliver this benefit to the consumer.

Two hundred years ago, when the whole of France was in flux, Nicolas Appert sparked a global revolution in food preservation. Today this revolution is still going on, but the focus has shifted inwards.