Surface phenomena of fats for parenteral nutrition

Summary Surface tensions of natural vegetable oils of known origin and processing conditions have been measured over the temperature range 25°–27° by means of a modification of the capillary rise method. Interfacial tensions against water of the crude and refined oils have been determined at 25°. The surface tensions and interfacial tensions against water of 1,3‐dipalmito‐2‐lactin at 75° and of a synthetic fat at 55° have been determined. The method of Least Squares was applied to the surface tension‐temperature data to obtain equations of the form, γ=a−bt, where γ is the surface tension in dynes cm −1 , t is the temperature in °C., and a and b are the least square factors. Only the crude rice, olive, and cottonseed oils have interfacial tensions against water less than 10 dynes cm −1 . Of the refined oils, coconut oil has the lowest interfacial tension, namely 12.8 dynes cm −1 . All of the other refined oils have interfacial tensions between 14.5 and 22.9 dynes cm −1 at 25°. The addition of unsaponifiable matter to a refined oil had little effect on its interfacial tension, but the addition of a small percentage of a crude oil to a refined oil lowered the interfacial tension of the refined oil considerably.