Animal fats. IX.—The relation between composition and iodine value

Consideration of the composition of animal fats containing little or no C20–22‐acids (39 fats of iodine value 31–96 from 30 genera) suggests an empirical relation between the iodine value and the amount of each component acid. This relation is expressed mathematically and the general conclusions are stated. Changes in iodine value are reflected almost entirely in the varying proportions of saturated, mono‐ and poly‐ethenoid C18‐acids. The changes in the proportion of each of these in animal fats of iodine value 90 falling to 30 are parallel to changes which occur during selective hydrogenation of mixtures of stearate, oleate and linoleate. ‘Stearic‐rich’ depot fats appear to be produced only by ruminants, quasi‐ruminants and ruminant‐feeding animals.