Freeze dehydration of foods has been developed in the past decade with such full success that it is now beginning to find wide application in the food processing industry. Now irradiation of foods seems just on the threshold of similar development as another radically new technique of food preservation. The papers in this volume report on specific successes and problems in the continuing investigations of the MIT Department of Nutrition and Food Science on these techniques. Originally presented to an MIT symposium of food-industry researchers in 1963, the papers deal with radiation preservation, isolation and identification of off-flavor food components, basic microbiological studies, the use of bacterial sensitizing agents, the complimentary effects of heat and radiation, and radiation preservation of sea food; papers related to freeze dehydration report active researches on raw material quality, processing parameters, storage vectors, and microbiological factors; food safety, wholesomeness, and nutritive value in relation to new preservative methods are also discussed.