Joseph C. Longridge, 75, a retired food broker who was active in Prince George's County civic and charitable organizations, died of a cardiovascular ailment Monday at Leland Memorial Hospital in Riverdale.

A food broker for more than 45 years, he sold to institutions such as schools and government installations. He retired about four years ago.

Mr. Longridge, a Democrat, served as councilman at large for College Park and chaired the Prince George's General Civic Improvement Committee during the 1950s.

In 1953, he was chairman of the March of Dimes program for the mass inoculation of children against polio in Prince Georgehs County. He was campaign chairman of the Tuberculosis Association in 1962 and served on the board of the Heart Fund during the 1960s.

He was a director of the Prince George's Chamber of Commerce and the University of Maryland Alumni Council, and had been president of the Rotary Club of College Park and the business and public administration alumni of the University of Maryland.

Mr. Longridge had received an outstanding citizen award from the Lions club.

He was a native of Barton, Md.,and a graduate of the University of Maryland.

Survivors include his wife, Katherine A., of the home in Hyattsville, a daughter, Katharine L. Barnes, of Baltimore; three sisters, Oma Neff, of Morgantown, W.Va., Mary M., of Barton, and Inez Pearson, of Los Angeles; a brother, Kermit C., of Idaho, and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the St. Andrews Episcopal Church Memorial Fund in College Park.