Reacting triglycerides with a strong base will give you the fatty acids and glycerine. In order to separate the fatty acids from the glycerine, acidify the solution with HCl. The fatty acids are insoluble in water at low pH. The glycerine is soluble in the water at a much wider range or pH. This will cause the acid to crash out and the glycerine will stay in the water. You can also do an organic extraction of the acidified water to recover any remaining fatty acids.