Time was, the ritual of the cork was one of the hallowed traditions of restaurant wine service. The waiter arrived with the bottle, removed the foil capsule, worked the worm of the corkscrew into the cork, and slowly withdrew the cork, producing that satisfying “thwock.”

Then came the ritual pour, so the person who ordered the wine could determine if it displayed an “off” aroma.

That little wine-drinking ritual in which the waiter pulls the cork and pours an ounce for the person who ordered the wine remains intact. But the original purpose has been altered as the trend moves away from real cork as a bottle closure.

A chemical in the cork can ruin a wine. If a cork is affected with even just a tiny amount a chemical called 2-4-6-trichloroanisole (TCA for short), the aroma of mold or wet dishrag is the result. TCA can ruin a bottle of wine, and what wine lovers say is that the wine is “corked.”

Cork, the product of a tree (the bark of the cork oak tree), varies in quality and is susceptible to taint problems. Though it has been used for hundreds of years to seal bottles of fine wine, for decades, some 4-to-5 percent of all wines were ruined by TCA contamination.

But as wine consumption increased and the demand for cork rose, more marginal cork was used to make the wine-bottle stoppers, and that led to an increased incidence of “off” bottles — in some cases, double what it had been. And that led to the development of alternative closures.

One was the aluminum screw cap. It simplified the opening of a bottle of wine and was taint-free — but it was used primarily on cheap wines, and its image was diminished.

At the same time, a number of the world’s cork-makers came up with a solution of sorts. They began to use ground-up cork that was treated to lessen TCA potential. Glued back together into a plug that would seal wine bottles, these were called “agglomerate corks.”

Many of them worked fine until one company, then called Sabate, began to deliver agglomerated corks to wineries worldwide in a way that seemed to exacerbate the tainting problem. These Altec-brand corks seemed to be infected with a tiny amount of TCA. After a while, the word was out: Altec corks gave wine a unique, Altec-TCA tainted character.

Because of this, many wineries began to experiment with synthetic closures, made of plastics or resins. In 1989, St. Francis winery in Sonoma Valley made a test run of some synthetic corks that proved acceptable. But soon some problems were seen with some of the synthetics. One was elasticity. There was concern that over time, they would lose their grip inside the bottle and fail. Also, a few of the synthetics were hard to remove from bottles.

Moreover, some wine makers believed that natural cork permitted red wines to age better than a synthetic or a screw cap. So, despite the risk of TCA taint, they stayed with cork.

The controversy persisted. On the one hand, few producers of top-quality wines would risk using a closure other than cork. Screw caps were especially anathema. Yet there were some significant examples of closure adventurers.

• New Zealand wine makers, virtually nationwide, adopted the screw cap, and soon its acceptance as a closure for fine wine began to be recognized. Australians now increasingly are using screw caps, especially for early drinking wines.

• Bonny Doon Winery in Santa Cruz declared that the cork was dead and switched its entire line of wines to screw caps.

• Napa Valley star cabernet sauvignon producer PlumpJack and great Aussie shiraz maker Giaconda were just two of the super-premium brands that gave buyers a choice: cork or screw cap.

• Domaine Chandon began to use a crown cap (like those once found on soda bottles) for its super-premium étoile wines.

• Sabate eventually was sold to a new group of owners, who changed the company name to Oeneo. Today, the company’s Diam agglomerated corks seem to have solved the TCA problem by using a supercritical carbon-dioxide treatment process to treat the ground-up cork.

Still, getting consumers to accept alternative closures hasn’t always been easy. Some of the strongest early opposition to screw caps came from wine stewards and sommeliers in restaurants where the ritual of the sample pour to determine whether the wine was “off” or not was placed in jeopardy.

The reason was economic: They believed that if the wine server no longer did the “hard” work of removing the cork and if the ritual pour was unnecessary (because screw capped wines are almost never corked), the gratuity might suffer.

Today, however, the use of screw caps is on the rise, acceptance is growing and Diam’s agglomerate corks are now rated among the best alternative closures. And numerous synthetic closures are widely touted as perfect solutions because they are inert and inexpensive.

Wine of the Week: 2007 Villa Maria Unoaked Chardonnay, Marlborough ($16) — This stylishly fruity New Zealand wine, sealed with a screw cap, is fresh and lively with a tropical fruit aroma and superb freshness, with a depth few grapes can deliver. A delightful quaffing wine or one to serve with lighter seafood dishes.

Dan Berger resides in Sonoma County. Berger publishes a weekly newsletter on wine and can be reached at danberger@VintageExperiences.com.