Acid oil is a general term for a by-product obtained from the alkali refining of oils and fats. during alkali refining  the  free  fatty  acids  are  neutralised  with  alkali  and  this  soapstock  containing  some  emulsified  neutral  oil  is  separated.  Acidification  of  the  soapstock  gives  acid  oil.  Main  components  of  acids  oils  are  fatty  acids,  neutral  oil  and moisture. Acid oil requires further refining/purification before it is suitable for use in laundry soaps and washing powders.

    FFA......................................................40-80%
    Moisture & impurities............................<3%
    Total fatty matter..................................>95%
    Consistency...........................................Semi-solid
    Color.....................................................Brown