Elaine Sciolino: In cod they trust, but should it be salted or frozen?

COD, the salted, cured, dried, smelly kind, may be the closest thing this country has to a national symbol. Bacalhau, as the fish is called here, is to Christmas Eve in Portugal what turkey is to Britons.

Treasured since the 16th century, when Portuguese fishermen first brought it back from Newfoundland, it bore the nickname fiel amigo – faithful friend. Its correct preparation is a source of pride, a sign of respect for family values.

Every Portuguese, it seems, likes to boast that there are 1,000 recipes for bacalhau and that the people here eat more of it than do those anywhere else in the world.

"The greatest friend of Portugal is bacalhau," said Fernando Santos, an officer of the Friends of Bacalhau, a club that has 46 chapters around the world, hosts salt cod lunches and distributes cod-decorated neckties, badges, baseball caps, T-shirts and flags. "It has always come from afar, but it is part of our identity."

So as Christmas approaches, the rush is on to find the best-quality salt cod at the best price before supplies dwindle and prices soar. But the preparation – a ritual of soaking stiff, smelly slabs of fish in cold water that must be changed every few hours for two to three days before cooking – is less romantic than it once was. These days, more Portuguese are opting for frozen bacalhau.

"Frozen is the best, frozen is the future," said Goncalo Guedes Vaz, managing director of Rui Costa e Sousa, a major producer of both frozen and traditional bacalhau, at the company's state-of-the-art processing plant in this northwestern port city. "Women have no time to stay home and soak. So we do the job for them. Traditional cod soon will be a thing of the past."

Frozen, ready-to-cook bacalhau accounts for as much as 25% of the bacalhau sold in Portugal. In the year and a half since Rui Costa e Sousa has been freezing part of its catch, frozen cod has grown to about 2,000 tons, or 17% of its production. Within five years, the company says, it wants that figure to hit 50%.

"Look at those loins," Guedes Vaz said, pointing to fishy flesh in one of the processing rooms. "We do this much better than you can do it at home. We have total control."

To prove it, Guedes Vaz has set up a small corporate dining room, where Isabel Santos, a chef with no formal training but a lot of loyalty, prepares the company's premier frozen brand, Sr Bacalhau (Mr Cod), in half a dozen different ways.

"I used to make bacalhau the old-fashioned way, but since I discovered Senhor Bacalhau here, I am faithful only to him," she said.

The divide is on display in the retail markets in Lisbon, the capital. In the city's main supermarket, hundreds of salt-encrusted bacalhau piled high in one section compete with vast frozen cases of bacalhau in another. They receive equal praise. "I really don't see much difference in the quality," said Ana Dinis, the fish department saleswoman. "Frozen is more expensive, but frankly less salty, more reliable."

Every family has a horror story of the relative who spent days preparing bacalhau only to serve it too dry or too salty. In other words, inedible.

The changing culinary habits of the Portuguese are mourned as a loss of a part of the country's culture. "Frozen tastes nothing like real bacalhau, properly prepared," said Jose Bento dos Santos, a winemaker and the host of a television cooking show. "I doubt the next generation will know it, just as it will not know the taste of real strawberries or melons."

That view is shared on Rua do Arsenal, the old working-class shopping street for traditional bacalhau in the Baixa section of Lisbon. Although many of the shops have shut in the past 25 years, there is still so much salt cod here that the street greets passers-by with the smell of salt brine and pungent old fish.

"I never ate the frozen stuff, but I hear from people who have that it's disgusting," said Fernando Pereira, who sells nine grades of the stiff, salt-caked whole fish in his shop, King of Bacalhau, alongside dusty bottles of port, absinthe, whisky and olive oil, open sacks of beans and grains, and packages of cod cheeks, face and tongue.