Detecting and Profiling Sterols in Pre-Prepared Foods Using GC–MS

Sterol detection in pre-prepared dishes poses a significant analytical challenge because of matrix interferences arising from fats, oils, proteins, and complex seasonings. However, the detection of these molecules and how they affect the nutritional value of the food containing them are especially critical. A study conducted by the Zhejiang Provincial Center for Disease Control and Prevention, the NHC Specialty Laboratory of Food Safety Risk Assessment and Standard Development, and Hangzhou Medical College (all in Hangzhou, China) set out to develop a sensitive, selective gas chromatography-mass spectrometry (GC-MS) method for simultaneous qualitative and quantitative multi-component sterol analysis in pre-prepared dishes and to examine their compositional traits. A paper based on this work was published in Frontiers in Nutrition (1).

A sterol is defined as any organic compound with a skeleton closely related to cholestan-3-ol and having a hydroxyl group at carbon 3. A subgroup of the steroids, the most familiar type of animal sterol is cholesterol, which is vital to the structure of the cell membrane, and functions as a precursor to fat-soluble vitamins and steroid hormones. While technically alcohols, sterols are classified by biochemists as lipids (2).

As the consumption of pre-prepared dishes grows, the precise determination of sterol composition and content is important in nutritional evaluation and safety control (3-5). Processing techniques such as high-temperature thermal processing and repeated oil use in pre-prepared dish manufacturing, however, have the tendency to generate oxidative degradation and structural isomerization of sterols (6-8).

The monitoring samples for the analysis were sourced from various links such as supermarkets, farmers’ markets, and online shopping platforms. The edible parts from the total of 37 samples of prepared dishes were collected (including main ingredients, auxiliary ingredients, and seasonings). The samples were then poured into a homogenizer, with inedible portions such as bones removed, ground up, and then transferred into two 50—mL plastic centrifuge tubes. After saponification treatment, the samples underwent ultrapure water-assisted dispersion and n-hexane extraction, with extracts dried and subjected to derivatization reaction. The derivative is redissolved and analyzed by GC-MS for qualitative identification, with quantification performed using the internal standard method, which, according to the researchers, “optimizes sample pretreatment and chromatographic separation conditions, enhancing detection efficiency and separation effectiveness.” (1)

The six target sterol compounds exhibited good linearity within the concentration range of 1.0-100.0 μg/mL (correlation coefficients ≥0.99). The limits of detection (LODs) and limits of quantification (LOQs) were 0.05-5.0 mg/100 g and 0.165-16.5 mg/100 g, respectively. At low, medium, and high spiked concentrations, the average recoveries ranged from 87.0 to 106%, with relative standard deviations (RSDs, n = 6) of 0.99-9.00%. Application of this method to analyze actual pre-prepared dish samples revealed significant variations in cholesterol content among different dish categories, with meat ingredients playing a dominant role. The sterol composition exhibited marked diversity: ergosterol was not detected in pre-prepared dishes, while β-sitosterol, campesterol, and stigmasterol constituted the major components. Notable differences in sterol content and composition were observed across different categories of pre-prepared dishes, further confirming the impact of various meat raw materials and processing technologies on sterol levels.

“The GC-MS analytical method established in this study has been validated to demonstrate excellent reliability and applicability, providing an efficient analytical tool for precise detection of multi-component sterols in pre-prepared dishes,” the authors wrote. “This method supports quality control and nutritional value assessment in the pre-prepared dish industry, facilitating product labeling standardization and informed consumer choices.” (1)

However, the researchers are aware that their study has limitations. “The method’s application is currently limited to meat-based pre-prepared dishes, and its adaptability to pre-preapred meals

interference mechanisms of processing parameters, such as the duration of high-temperature treatment or the frequency of oil usage, on sterol detection results have not been systematically investigated. Moving forward, the group plans to broaden the range of sample matrices—such as plant-based and seasoned pre-prepared dishes—to test the method’s universality, and develop a correlation model connecting processing parameters, sterol changes, and nutritional safety through the integration of sterol oxidation product detection. These efforts aim to enhance the method’s contribution to safety–nutrition control in pre-prepared dishes (1).

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References

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2. Sterols. Wikipedia. https://en.wikipedia.org/wiki/Sterol (accessed 2025-11-06)
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