Pulsed NMR Method for Solid Fat Content Determination in Tempering Fats, Part I: Cocoa Butters and Equivalents

Abstract

AbstractA general pre‐treatment and measuring procedure is described for Solid Fat Content (SFC) determination with pulsed NMR on tempering fats (i. e. Cocoa Butters and Cocoa Butter Equivalents). These fats need a careful pre‐treatment to reach their stable β‐polymorphic form and crystal size. The different steps in the analysis were studied and optimized to give reliable and quick results. Critical steps were found to be how to start the crystallization from the melted fat and the tempering process. The fat sample should be completely melted at 80° C and held at 60° C for 20 min. Commencement of crystallization is carried out at O° C for 90 min and tempering at 26.5° C for 40 hours. Cooling is carried out at O° C for 90 min before the serial measuring procedure with 35 min/bath using 10,20,25,27,5,30,32.5,35,40 and 60° C baths. Only the liquid signal is measured (indirect method) and 1 puls with 6 sec trigger time used. The temperature dependence of the signal is compensated with a liquid soya oil. The standard deviation for the described method was 0.3–1.8% (abs) with the highest deviations at temperatures in the very intensive melting range, showing that the temperature accuracy and stability in these baths is of greatest importance. A method to check the tempering process with SFC determinations at 26.5° C for various tempering times is also proposed.