Clinton L. Brooke, 78, an authority on nutrition and cereal chemical, died Jan. 1 at the Fairfax Nursing Home after a long illness.

Mr. Brooke, who had traveled extensively abroad in connection with his work, had lived in the Washington area since 1963.

Born in Minneapolis, he attended the University of Minnesota and started work as a chemist at the Minnesota State Testing Mill in 1921.

Three years later he went to Sweden to install one of the first flour mill laboratories in that country at Uppsala.

Later, Mr. Brooke was with the American Dry Milk Institute and the Pillsbury Co. He worked as a research fellow and took graduate studies at the University of Minnesota.

After serving as a sales manager of the National Yeast Co., Mr. Brooke joined Merck and Co., Inc. in 1943, remaining there for 20 years. During those years, he was sent to Chile, Brazil, Taiwan, Saigon, Madrid, Cairo and other countries as a food consultant and adviser on nutrition.

Mr. Brooke joined the Foreign Agricultural Service of the Agriculture Department in 1963.

A year later, he was appointed assistant agricultural attache at the U.S. Mission to the European Communities in Brussels, Belgium.

He became a consultant to the Agency for International Development in 1966 and traveled to Jordan, India, Ethiopa, Brazil and Guatemala.

In addition to the American Association of Cereal Chemists, of which he was a past president. Mr. Brooke belonged to the American Society of Bakery Engineers and the Institute of Food Technologists. He was a Fellow of the American Association for the Advancement of Science and a former director of the American Institute of Baking.

He is survived by a son, Tyrrell, of Vienna, Va.; a daughter, Margaret Brooke, of Decorah, Iowa; a brother, Truman, of Spokane, Wash.; a sister, Elizabeth Morrison, of New Port Richey, Fla., and three grandchildren.