Averting a threatened strike by area food industry employees, meatcutters and retail store clerks for most of Washington and Baltimore's major supermarkets yesterday ratified a new, three-year contracts with seven food store chains.

In separate meetings, Washington Local 593 and Baltimore Local 117 of the Amalgamated Meat Cutters and Washington Local 400 of the Retail Store Employees agreed to contract terms reached early yesterday. The agreements came after around-the-clock bargaining by union representatives, supermarket officials and U.S. mediators who were called into the negotiations last Friday.

The contracts, which cover about 30,000 supermarket employees represented by four unions, provide for a 50 cent across-the-board wage increase in each year plus cost-of-living raises and improvements in vacation and health and welfare benefits.

The old three-year contracts with Safeway, Food Fair-Pantry Pride, Giant, A&P, Grand Union, Lucky Markets and Memco expired over the weekend, and some unions had threatened to strike Tuesday unless agreement could be reached by midnight yesterday.

The contracts considered by the four locals are almost identical, according to one union spokesman, although there are some minor differences related to job grade and geography.

In Baltimore Local 117, for example, a journeyman meatcutter's hourly wage will increase to $9.09 by the third year of the contract. Retail store clerks and cashiers will be earning somewhat less, although no union spokesman was available to provide exact wage scale information.

In what was described as a major concession, the supermarket chains agreed to maintain health and welfare benefits at the existing level over the life of the contract and management agreed to pick up $1.1 million in preminums owed by the unions to Blue Cross.

The parties in the negotiations also agreed to terminate their contracts with Blue Cross/Blue Shield and to set up their own self-insurance carrier.

Additionally, the contract provided for five personal vacation days to be taken at an employee's convenience for any purpose and severance pay in addition to pensions.

Baltimore Local 692 of the Retail Store Employees, the fourth union covered by the agreements, was expected to meet last night to vote on the new contract terms.