Refined Glycerine – Animal Fats Based
Recovery of Fat
First of all, animal fats are collected from slaughterhouses. The fat tissue from animal parts is cooked. The elevated temperature ensures the fat to be released in liquid state and promotes cell rupture. On the other hand, an alternative method requires partial heating and the mechanical rupture of the fat tissue to release fat.
The degumming process of animals is the removal of dissolved phosphatides through centrifugation. Water is added to the oil that allows the precipitation of phosphatides. The newly formed precipitate is heavier as phosphatides readily absorb water. The centrifugation process separates the heavy phosphatides from the oil phase to the water phase.
Bleaching of oil is required to release unwanted pigment and other oxidizing agents that may alter the appearance of the product. Bleaching is performed by adding charcoal or earth clay. The existing pigment from the oil will be adsorbed by the charcoal. On the other hand, an additional method by chemical reaction is required for edible oils (oxidation and reduction reaction).
The adsorbed oils are further treated for scent and foul odour removal. Steam distillation is utilized to remove any volatile impurities that contribute to the unpleasant smell. Steam distillation makes use of the non volatile animal fat to remove any aldehydes, ketones, and other compounds that are classified as an impurity. In a distillation chamber, high pressure is injected under vacuum conditions around 180-250 degrees centigrade. The non-volatile triglyceride remains unchanged while volatile impurities cascade upwards and are removed from the animal fat.
The animal fat is decomposed by hydrolysis reaction under high temperature and pressure. The process utilizes water to break down the chains of triglycerides into glycerol/glycerine and chains of fatty acid. In this step, glycerine becomes available for extraction; however, further refining is required for the newly made glycerine to be called refined glycerine.
The mixture of glycerine and chain of fatty acids is further refined by a series of separation processes. The oil mixture is distilled to separate the fatty acids from the desired glycerine. The distillation column is heated to promote evaporation of both glycerol and fatty acid. Glycerine has lower boiling point; therefore, glycerine will evaporate readily at a certain range temperature whereas the chains of fatty acid will remain as liquid.