How quickly a fat sets
Solid fat content tells you how much of a fat is solid once it has settled. Isothermal crystallisation adds the time dimension: how long the fat waits before the first crystals appear, how fast the solid content builds up, and where it ends.
These three numbers decide how a product behaves on the line. A fat that sets too slowly gives soft, sticky or poorly formed products and a higher risk of bloom, the grey-white film that appears on chocolate and coatings. A fat that sets too fast can clog equipment or give a coarse texture.
When a fat crystallises in two steps
Many fats can crystallise in more than one crystal form, called polymorphs. The first crystals to appear are usually the less stable forms, and over time the stable β form can follow. In the curve this shows up as a second crystallisation phase: the solid content levels off after the first step, and after a pause it rises again.
Whether the second phase is wanted depends on the product. In chocolate, the stable β form is the aim, because it gives gloss and snap. In margarines and spreads, large β crystals can make the texture grainy. A curve that shows both phases lets you see when the second phase starts, and how a recipe, an additive or a cooling routine changes it.
Where it is used
- Cocoa butter, cocoa butter equivalents and substitutes
- Fats in chocolate, coatings, fillings and confectionery
- Palm, palm kernel and coconut fats and their fractions
- Shortenings, margarine and spread fat blends
- Milk fat and its fractions
- Fats with added emulsifiers, seeding agents or other crystallisation modifiers
Typical tasks are choosing between fats for a coating or filling, testing what an additive or emulsifier does to the setting speed, qualifying a supplier batch for its setting behaviour, checking a tempering routine, and finding the reason for slow setting or bloom.
The same signal, followed over time
The measurement uses the same principle as solid fat content: the signal of the solid part and of the liquid part of the fat are told apart, without chemicals and without destroying the sample.
The fat is first melted, so that any earlier crystal history is erased. It is then cooled quickly to the chosen temperature and held there in a temperature-controlled block, and the solid content is read again and again at regular intervals. The readings together form the crystallisation curve.
What it adds
- The same sample is followed from start to finish, so one tube gives a whole curve
- No solvent and no sample preparation beyond melting and cooling
- Several samples can be measured under identical conditions and compared directly
- The curve comes from the whole sample, whatever its colour or opacity
- The method can be automated for series of samples and temperatures
Points that matter in practice
- Small differences in temperature change the setting speed a lot, so the temperature control and the cooling step must be the same every time
- Choose the temperature, or temperatures, that match your own process
- Run the measurement long enough to catch a second phase. Stopping after the first plateau can hide it
- Very fast-setting fats begin to crystallise while the tube is still reaching temperature, so the first readings depend on how quickly it cools
- Unlike solid fat content, there is no single universal procedure. Temperature and reading times are normally agreed between supplier and customer, and the same routine should be used whenever results are compared
- Together with the melting profile, the curve gives the full picture: how much is solid, and how fast it gets there
From your fat to a routine method
Send or bring representative samples. MSY Consulting runs feasibility measurements, helps you choose the temperatures and reading times that match your process, sets up the cooling and tempering routine, and trains your team until the measurement is part of your routine.
Let's talk about your application
Send an email describing your instrument and your application, and you will get a reply.
contact@msyconsulting.euMSY CONSULTING SAS · Wissembourg, France · LinkedIn