While a Virginia Senate committee was voting down a bill to cut in half the state's sales tax on food earlier this week, another measure giving restaurant owners a $1.5 million-per-year tax break on their liquid purchases cleared the legislature with little fanfare.

The measure, which Fairfax Sen. Clive DuVal branded "special interest legislation of the worst kind," is one of nearly a half-dozen tax bills designed to help business groups and wealthy individuals that has won approval from the General Assembly this year.

Besides restaurant owners, the winners include coal companies, banks, oil companies investing in gasohol projects and luxury boat owners. Their success, legislators say, is a reflection of the impact lobbying has in Richmond.

"Every successful tax repeal measure has had at least one highly paid efficient lobbyist pushing it and that's the bottom line," said Sen. Dudley Emick (D-Botetourt). "At the same time, there's no such thing as an organized citizens' lobby -- it just doesn't exist."

As other tax-cutting bills were dying under claims that they would strip the state's tax coffers of too much revenue, lobbyists for special interests were able to dodge such complaints. Some items:

Coal companies won a state sales tax exemption for heavy equipment used outside their mines. (They already had an exemption on machinery used in the mines.)

State-chartered banks won a major reduction in their annual franchise tax payments.

Buyers of boats more than 15 feet long also got an exemption from the four percent state sales tax. In return they were saddled with a two percent title tax, which in effect cuts their purchase taxes in half.

The willingness of the assembly to create such tax benefits has angered some legislators. "The message we send home is that it's irresponsible to cut taxes for people, but it's responsible when it comes to corporations," said Del. Warren G. Stambaugh (D-Arlington).

Stambaugh, working almost single-handledly, managed to kill a bill today that would have given companies building gasohol plants a 10 percent write-off of expenditures on their state income taxes. Addressing the house, he referred to it as "the Texaco tax break bill." It was defeated 65 to 28.

Critics say the restaurant liquid bill, which eliminates the $2-per-gallon tax that the state charges liquid-by-the-drink sellers, is a prime example. The bill was cosponsored by Sens. A. Joe Canada, whose Virginia Beach constituency includes scores of restaurateurs, and Peter Babalas of Norfolk, a lawyer whose clients have included a number of restaurant owners.

Both pushed hard for the bill, as did J. William Doswell, a professional lobbyist who during last year's two-month session reported earning $15,000 lobbying for the Virginia Restaurant Association, the interest group behind the Canada-Babalas bill.

The Senate Finance Committee first killed the bill by a 10 to 4 vote with indignant senators condemning the idea of giving the restaurant owners a $1.5 million annual windfall. But the committee reversed itself the following week after the association members and Doswell went to work.

"Everyone's got restaurants in their districts and suddenly they were getting lots of phone calls and restaurant people visiting thier offices," said Fairfax's DuVal after the committee approved the bill 7 to 6.

Three committee members who had opposed the bill said they were convinced to change their votes by Canada's argument that the tax cost so much to collect that it made little or no money for the state and localities. A fourth opponent, Sen. William A. Truban (R-Shenandoah), took a walk during the second vote.

"I had to go to the bathroom," Truban said later, denying he had been persuaded to duck the vote. But other senators credited the lobbying campaign by Doswell, who could not be reached for comment today. The bill went on to pass the Senate narrowly, then won easy approval from the House of Delegates.

Like the restaurant bill, the sponsors of most of the other tax-break measures gave compelling rationales for their bills. Del. Richard Cranwell (D-Roanoke County) said his mine equipment sales tax exemption bill simply gave coal companies the same tax break other manufacturers have. House Majority Leader Thomas W. Moss of Norfolk, who has hundreds of boat owners in his seaside district, contended that by establishing a title system his bill would make it easier for local revenue officials to track down boat owners who had been avoiding paying annual personal property taxes on their vessels.

In the case of bill reducing the bank franchise tax, proponents argued that the 9 percent tax on the capital of state-chartered banks scheduled to take effect in 1982 had only been designed to produce extra money to cover possible losses expected from court-ordered refunds of another tax that state courts had declared illegal. Since lawsuits over the old tax had been settled, some legislators contended the franchise tax should be reduced to its previous one percent.

Special interest groups also were successful in killing bills that would have raised taxes on their products. A bill allowing two impoverished Southwest Virginia counties to increase local cigarette taxes to pay education went down to its annual defeat after tobacco lobbyists argued it could hurt the industry. Oil company lobbyists worked to kill a companion measure that would have allowed the same counties to levy a special tax on properties leased for oil and gas exploration.