Download Freeze-thaw stability of emulsions – model system ”mayonnaise”

May 2009
Freeze-thaw stability of emulsions – model system
”mayonnaise”
Diploma project 30p
Background
Källbergs Industri AB produces and markets speciality type of products for mayonnaise based
on egg yolk. During later years the sales have increased considerably and products are
exported to a number of countries such as Russia, Ukraine, Bulgaria, Great Britain and
Kazakhstan. An important property for a mayonnaise is if it can withstand freezing followed
by thawing without that the emulsion breaks.
Goal
The project goal is to create an increased knowledge about freeze-thaw stability of
mayonnaise.
Description of the problem
Mayonnaise is generally known as an oil-in–water emulsion. In order to prolong the shelf life
or due to practical circumstances during transport is the mayonnaise often frozen. During the
freeze-thaw procedure is the emulsion destabilised and partial or complete separation in oilrespectively water phase often occurs.
The freeze-thaw stability of the emulsion is affected of mainly two mechanisms:
- The successive increase of dissolved substances in the liquid water phase. High
concentrations of salts and/or sugars then changes the conditions at the surface between the
oil and water phase.
- The dispersed oil droplets are affected by mechanical stress when the water phase expands
during freezing. Due to this there is an increased risk that the adsorbed layer surrounding the
individual oil droplet ruptures.
Methods:
During the project the influence on freeze-thaw stability will be invesitgsted with respect to
some selected process and formulation parameters. Potential parameters to evaluate are:
- quality and origin of the vegetable oil
- quality of egg yolk (natural composition or enzymatically modified)
- quality of the emulsion (size and distribution of the oil droplets)
- influence of salts – ion strength
- ratio between water and oil phase
- ingredients as emulsifying OSA-starch, hydrocolloids and milk proteins, etc
Analytical methods;
Measurements of drop size distribution, rheological measurements, degree of separation after
thawing, separation after centrifugation etc.
The thesis subject can be food technology, biotechnology, pharmaceutical technology or
another similar subject relevant for the student. The starting date can be anytime.
If you are interested contact: [email protected] or [email protected]