FAO: FAO's International food composition table/database directory provides a list of food nutritional composition publications and databases, many of them in downloadable form at http://www.fao.org/infoods/infoods/tables-and-databases/en/.
WFP, WHO, UNICEF, UNHCR: A 57-page manual "Food and Nutrition Needs in Emergencies" can be downloaded as a pdf or printed from the following link http://whqlibdoc.who.int/hq/2004/a83743.pdf. It was prepared by WFP, WHO, UNICEF and UNHCR and contains tables showing nutritional requirements by age and sex as well as the nutritional content of selected food aid commodities. It also provides examples of how to calculate emergency rations.
WFP: WFP provides a table of basic information on the nutritional composition of foods used in WFP emergency feeding programmes. This data is in pdf format at http://www.wfp.org/fais/nutritional-reporting/food-composition-table. Note that the coefficient for iodine in the data for iodized salt is not correct.
Other nutrition pages: