These are the companies that supply different parts of the school lunch in Prince George's County:

Mazo-Lerch. An Alexandria-based wholesale grocery business, which just celebrated its 50 anniversity. The company, an institutional supplier, wholesales dry and frozen groceries. It is a family-owned corporation with about 140 employees in both its Alexandria and Richmond locations and with sales of about $20 million to $25 million.

Embassy Dairy, Southladn Corporation, a Texas-based conglomerate which includes 7-11 convenience stores, acquired Embassy in about 1965. The Embassy division, with about 200 employees, moved from the District to Charles County about a year and a half ago. Embassy also supplies milk to the D.C. schools.

Washington Beef (Kolker Brothers). Located in northeast Washington, Washington Beef has about 150 employees and sales of about $17 million. It is a family business, started in the 1930s, and an institutional supplier that provides beef, lamb, veal and pork to major restaurants in the area as well as to institutional such as schools.

Tastykake. A division of Tasty Baking Company in Philadelphia, which also has divisions for graphic arts, toys, cookie distribution and frozen desserts. Tasty Baking Company had sales of about $157 million and about 2,200 employees in 1976. It was founded in 1914.

ITT Continental Bakery.Manufacturer of Wonderbread and a division of ITT. Had sales of $1,181 million and 28,000 employees, according to the 1977 Dun's Million Dollar Directory.

Abbotts Dairies. A division of Fairmont Foods, a Houston-based corporation involved in milk, ice cream, snack food, bakery products and grocery chains. Fairmont Foods had sales of $515 million and 8,972 employees, according to Dun's.

Various vendors provide fresh fruits and vegetables, which cafeteria managers buy themselves. "We find it more economical to buy on an as-needed basis than to bid for produce," said food services director C. Anthony DiMuzio. "We don't have to have refrigeration to handle it, and we don't have to buy in larger quantities than needed. Some schools wouldn't use a case of lettuce a week," he said.