Importance of derivatization in cholesterol analysis using GC-FID for bakery products containing plant and animal lipid

Abstract

Cholesterol can be analyzed using derivatization and non-derivatization techniques. Analysis without derivation is a simple and reproducible method for some samples. However, cholesterol and α-tocopherol could be eluted together during gas chromatographic analysis if the sample contains both analytes. In this study, the importance of derivatization in cholesterol analysis in bakery products was investigated. Derivatized and non-derivatized cholesterol and α-tocopherol standards were eluted on HP-5 capillary column in GC-FID. The cholesterol and α-tocopherol standard resolution (Rs) using derivatization technique was 3.1 which is considered as well separated (> 1.5) based on AOAC guidelines. However, cholesterol and α-tocopherol were coeluted by GC-FID without derivatization. The GC-FID cholesterol analytical method was validated and applied for cholesterol determination in bakery samples. Method validation results were effective to be used for bakery products: limits of detection (0.03 mg/100 g) and quantification (0.08 mg/100 g), accuracy (102.1% recovery) and precision (repeatability: relative standard deviation (RSD) 1.5%; reproducibility: RSD 1.9%). The cholesterol content of bakery products range from 2.76 ± 0.06 mg/100 g (castella) to 114.26 ± 4.72 mg/100 g (chrysanthemum bread) depending on the ingredients used. This study shows that derivatization step is essential in cholesterol analysis of bakery products containing both cholesterol and α-tocopherol to prevent possible overestimation of cholesterol.