Sterols in fresh and preserved button mushroom (Agaricus bisporus) products

Abstract

Mushrooms are highly valued but also very perishable foods. As a consequence, various types of preserved mushroom products are available in retail stores. Common preservation techniques include pickling in brine and drying. Such processes might cause a partial transformation of unstable products like ergosterol, which is the most relevant sterol in mushrooms. In this study, gas chromatography with mass spectrometry (GC/MS) was used to examine the levels of ergosterol and other, lower abundant sterols in dried and pickled button mushrooms ( Agaricus bisporus ) from German retail. Multivariate analysis of the free sterol fraction was used to verify significantly lower ergosterol contents in the preserved products (pickled: 280 ± 30 mg/100 g dry weight, dried: 190 ± 20 mg/100 g dry weight) compared to fresh button mushrooms (610 ± 20 mg/100 g dry weight). In addition, the contribution of ergosterol to the total sterol content in dried button mushroom samples (84 ± 1%) was comparable to fresh samples (87 ± 1%) but significantly lower in the pickled products (78 ± 1%). Storage experiments with pure ergosterol standards in solution indicated a full degradation of ergosterol and the formation of seven transformation products at room temperature storage within 9 days.