Mayonnaise: Quality and Catastrophic Phase Inversion

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.Mayonnaise: when it breaks and effects on quality When mayonnaise is made there is a risk that it breaks when the oil is added, making the maker disappointed. How fast the oil can be added and how other parameters affect when the mayonnaise breaks has been investigated as well as how the quality of mayonnaise develops during whipping. Mayonnaise is a tricky sauce to make and getting the right quality without causing the mayonnaise to break is a challenge even for the best chefs. The main ingredient in mayonnaise is oil (approx. 80%) but it also contains water, egg yolk, mustard, vinegar, salt and sugar. By mixing, either by hand or with an industrial mixer, the oil is broken up into many small oil droplets which are covered by a layer of egg yolk protein and packed tightly in water. A high quality mayonnaise has many small oil droplets and a firm texture. The most common problem with mayonnaise is that it breaks if the oil is added too fast, which has caused a lot of disappointment in the kitchen. The same problem can also occur in the industry resulting in both food waste and economical losses. In order to get a better understanding of how fast the oil can be added to the mixer without causing the mayonnaise to break, both an industrial pilot scale mixer and a regular immersion blender were used to make mayonnaise. The results show that there really is a limit for how fast the oil can be added and that it is independent of mixing speed. Instead, the formation of mayonnaise seems to be dependent on having the rotating part of the mixer (rotor) in the water and not in the oil. If the rotor is in the water you get mayonnaise and if it is in the oil the mayonnaise breaks. The oil can be added faster when the first 20% of the oil is added slowly before the maximum rate is used. Changes that required the oil to be added slower were using room temperature ingredients instead of cold and using egg yolk powder. The effect of using egg yolk powder instead of liquid egg yolk was dramatic and mayonnaise could only be made using a very low oil addition rate. But conquering the broken mayonnaise is not enough, getting a mayonnaise with good qualities is just as important. The quality of mayonnaise was therefore investigated by measuring how firm it was and how small the oil droplets were. It was found that the texture of mayonnaise gets firmer during mixing until it reaches a maximum before it gets looser again. The droplet size has a minimum at the same time. This means that the mayonnaise reaches a highest quality before it gets over-mixed. Factors that gave lower quality were using less egg yolk and using room temperature ingredients instead of cold. Using egg yolk powder instead of liquid egg yolk gave firm mayonnaise with small droplets which is good but it had another flaw: it was slimy! When whole egg was used all three problems occurred, the mayonnaise was loose, had large droplets and was slimy. Mayonnaise made with increased oil content was firm but the mayonnaise broke during the mixing where more oil resulted in earlier breakage. The information concerning how both the oil-addition and the quality are optimized can be used in the industry to make the production better. This would result in a more sustainable production of mayonnaise with less food waste and economical losses