Mayonnaise: Quality and Catastrophic Phase Inversion

Sammanfattning: In industrial production of mayonnaise it is important to both get a product of high quality and to avoid phase inversion. To investigate how the quality and phase inversion point are affected by changes in the production, a high shear mixer and an immersion blender were used to make mayonnaise. The stirring speed, temperature, egg content, egg type and oil content were changed to see how the quality of the mayonnaise was affected. The maximum oil flow rate that could be used without getting a phase inversion was investigated where changes in stirring speed, temperature, egg content, egg type and addition of the oil was made. High quality mayonnaise has a firm texture and a small droplet size. Mayonnaise reaches a peak in texture and a minimum in droplet size during mixing. At longer mixing times the quality decreases and the mayonnaise becomes over-sheared. When the ingredients are cold and a high amount of egg yolk is used mayonnaise with a high quality can be made. Mayonnaise with an increased oil content has a firmer texture but is also more sensitive to over-shear. Phase inversion occurs in two different ways: when the mixing is prolonged and when the oil is added too fast. Mayonnaise made with increased oil content undergoes phase inversion after prolonged mixing. Traditional phase inversion of mayonnaise occurs when the oil is added too fast which means that there is a maximum flow rate. It was found that the stirring speed does not affect the maximum flow rate that could be used. Changes in temperature and egg content only gave small changes while changing the egg type to egg yolk powder required a very low oil flow rate. The information obtained in this master thesis can be used to make mayonnaise of high quality where phase inversions can be avoided.