The melting profile of a fat
Every fat is a mixture of solid crystals and liquid oil, and the share of each changes with temperature. Measured over a range of temperatures, the result is a melting profile: a curve that shows how a fat behaves from the refrigerator to the warm store room.
That curve is closely tied to what customers notice. It decides whether a spread is firm in the fridge and still spreadable soon after, whether a chocolate snaps and then melts cleanly in the mouth, whether a bakery fat holds its shape in the dough, and whether a product keeps its structure in a hot warehouse or oils off.
Where it is used
- Margarines, spreads and the fat blends behind them
- Shortenings and bakery fats
- Cocoa butter, cocoa butter equivalents and substitutes, and the fats in chocolate, fillings and coatings
- Palm, palm kernel and coconut oils and their fractions, and interesterified or hydrogenated fats
- Milk fat and its fractions
- Fats and waxes used in cosmetic and pharmaceutical products
Typical tasks are controlling a blend against a specification, comparing suppliers, checking incoming raw materials, and developing a new recipe around a target profile.
Know before you process
SFC is, above all, a control measurement. It tells you in advance whether a fat will behave as the customer expects, before it is shipped, accepted or used.
- Producers, refiners and blenders of fats check each batch against the customer's specification before it leaves the plant, so that a deviation is found at the source and not in the customer's production line
- Food manufacturers check incoming fats before they enter their own recipes, so that a batch that is too soft, too hard or too slow to set is caught before it spoils a production run
- Both sides can work from the same agreed profile and the same method, which makes contracts, complaints and supplier comparisons much easier to settle
- Blends can be corrected during production, because the effect of a change shows up in the melting profile within minutes
From a pulse to a percentage
In a solid crystal the hydrogen nuclei lose their magnetic signal almost immediately, while in liquid oil the signal lasts much longer. A short radio-frequency pulse and the following signal therefore separate the solid part from the liquid part, without any chemicals and without destroying the sample.
Two approaches are in use. The direct method reads the solid and the liquid share from one measurement. The indirect method compares the liquid signal at the test temperature with the signal of the same fat when fully melted. Both are described in international standards, and which one applies often depends on the specification you work to.
Because the result depends on how the fat has crystallised, samples are brought to temperature with a defined tempering routine before each reading. Temperature-controlled baths or Peltier units take care of this, and automation can run a long series of samples and temperatures unattended.
Recognised reference methods
- ISO 8292, part 1 (direct method) and part 2 (indirect method)
- AOCS Cd 16b-93 (direct) and AOCS Cd 16-81 (indirect)
- IUPAC 2.150
These documents set out the measurement and the tempering. Which of them your customers or your specification require should be confirmed before a method is set up, and the same method should be used whenever results are compared.
What it replaces, and what it adds
- Replaces the older dilatometry approach, which is slow and laborious
- No solvent, no extraction and no sample preparation beyond tempering
- Non-destructive, so a sample can be measured again at another temperature
- Quick readings and good repeatability suit routine quality control
- Can be automated for series of samples and temperatures
- Checked with reference samples as part of the daily routine
Points that matter in practice
- The result reflects the history of the fat, so the tempering routine has to be followed exactly
- Measure at the temperatures that matter for your product, not only at the standard ones
- SFC says how much of the fat is solid, not which crystal form it is. For polymorphs, other techniques complement it
- Results from the direct and the indirect method can differ slightly, so compare like with like
- Regular checks with reference samples keep results comparable over time and between instruments
From your fat to a routine method
Send or bring representative samples. MSY Consulting runs feasibility measurements, helps you choose the method and tempering routine that fit your specification, checks the calibration against your reference results, and trains your team until SFC 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