Solid fat content (SFC) detection method and application case

Solid fat content, SFC

Solid Fat Content (SFC) is a solid fat content at a certain temperature.

Natural oils are generally a mixture of solid oils and liquid fats at room temperature. Solid fat content (SFC) is a common measure of cocoa butter, margarine, butter, etc. It is the melting and hardness performance index of fat at different temperatures. Melting and hardness properties have a major impact on mouthfeel, aroma and spread properties.

The latest national standard GB/T 31743-2015 selects the NMR direct method as the test standard for solid fat content. The test uses the free induction decay sequence (FID), NMR direct method to determine the solid fat signal and liquid fat signal in the sample. Calculated to obtain a solid fat content SFC .

H in solid and liquid fats exhibit distinct properties in the FID decay curve due to their different forms. As shown in the figure below, the solid fat signal decays very quickly and is generally fully attenuated at 70 microseconds. The liquid fat signal decays slowly and is generally considered to have not been substantially lost at 70 microseconds. However, there is a specific dead time in the NMR signal acquisition, so when we collect the FID first signal S after the dead time, a signal of solid fat has been attenuated in the dead time (S'-S). The solid fat content SFC can be obtained by a certain signal processing.

NMR signal schematic

1. Preheat at 100 ° C for 15 minutes;
2. Preheat for 5 minutes at 60 ° C;
3. Preheat for 60 minutes at 0 °C;
4. Preheat for 30 minutes at the test temperature.

Testing at different temperatures

This method is to prepare a water bath for each test temperature, and then prepare different batches of samples to be placed in different temperature water baths, that is, each sample must be prepared for several different temperatures for several different samples in different water baths. After the first temperature of the first sample is measured, the second temperature of the first sample is measured, and then the third temperature of the first sample is determined. After the first sample is tested, the measurement is started. The first temperature of the two samples... and so on.
The problem encountered with the parallel method test is that a batch of samples of a sample has different thermal histories. Unlike the continuous method, one sample undergoes a series of temperatures; although it is faster than the continuous method using a water bath, the parallel method requires Many more sample tubes and more water baths.

A continuous process using a water bath, a water bath, was used for all test temperatures. All samples were at the same temperature before changing the bath temperature; although the number of baths was reduced, testing at different temperatures must first ensure that the bath temperature reached equilibrium, although all samples were used for all temperatures, but the balance between the two temperatures The difference will show some measurement errors and the entire test process takes longer.

Different water bath temperatures are used as in the parallel method. The continuous process requires as many water baths as the parallel method, where all batch samples are preheated at the same temperature before being transferred to the next water bath for preheating. It takes longer than the parallel method .

Solid fat content test case

Test instrument: PQ001 NMR solid fat content tester. (Manufacturer: Shanghai Newmai Electronic Technology Co., Ltd. ) .

PQ001 NMR solid fat content tester

Test results: The solid fat content of the two cocoa butter samples was tested at different temperatures. There are significant differences between the two cocoa butter samples. The solid fat content SFC size is: cocoa butter> low calorie cocoa butter (ambient temperature less than 30 ° C). The rate of solid fat melting in cocoa butter is greater than the rate of melting of solid fat in low calorie cocoa butter. .