The sterol ergosterol is a metabolite of yeast, mould fungus and edible mushrooms. It is formed in various amounts as an important membrane component. The ergosterol content can be used to assess the quality of the raw materials used in various tomato products (tomato puree, ketchup, sauces), and is therefore a suitable indicator of fungal and yeast infections of food (spoilage). Ergosterol is not destroyed by the heat treatments during the production of purees and ketchup.
After saponification, the sample is extracted using a solvent. The extract is semi-preparatively fractionated and purified using normal-phase HPLC. The ergosterol content is determined by HPLC separation on a reverse phase and UV detection. Quantification is by the method in our internal standards (based on DIN EN 12821).