Abstract:

To deal with the trade problems of new type products of fat powders caused by lacking suitable determination method of crude fat, a rapid and reliable determination method of crude fat in the products of micro-encapsulated fat powders was developed by selecting the micro-encapsulated fat powders with higher embedding rates as main testing samples and establishing the hydrolysis method and the extraction method. The testing scopes of this method were also studied. According to the requirements of the national standard GB/T 6379.2—2004 Accuracy of Measurement Methods and Results, the accuracy and precision of this method were then determined by testing the crude fat contents of five micro-encapsulated fat powder samples with different embedding rates in 3 independent labs. In this method, the sample (1-2 g) was hydrolyzed by 4 mol/L hydrochloric acid at 85℃ ± 5℃ for 1 h, and then the solution was extracted twice by petroleum ether (20 mL×2). After removing the petroleum solvent by distilling, the residue was dried at 103℃±2℃ for 15 min, then the residue was determined by Gravimetric method. After examined by Cochran test and Grubbs test, the results were found to be consistent and accurate without outliers. The average repeatability errors and reproducibility errors (RSD) of the method were 0.34%-0.58% and 0.38%-1.33%, respectively, indicating that this method could fully meet the precision requirements of the national standard GB/T 27404—2008 Specification for Laboratory Quality Control. This newly developed method is suitable for determination of crude fat in micro-encapsulated fat powder products without phospholipids, and is more accurate, fast and cost-effective, and more reliable when compared with the current standard GB/T 6433—2006.

Key words: micro-encapsulated fat powders, crude fat, determination, Cochran test, Grubbs test