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Abstract
Consumption of mushrooms is as old as the human civilisation all over the world. The aroma
is typical and special for each of the species of edible mushrooms. Despite their high
consumption, only few studies were concerned with their aroma. This research aims at
characterising the quality of the fresh and processed oriental mushrooms based on their
aroma profile. As the volatile compounds (VC) are produced via metabolic and
non-metabolic pathways, non-aggressive yet powerful techniques are needed to investigate
their chemical composition. Ambient temperature vacuum distillation was successfully
optimised to extract VC from fresh, boiled under reflux, dried at different temperatures (40,
50, 60, and 70 °C), and dried and boiled under reflux mushrooms. Four oriental mushroom
species, Agrocybe aegerite, Flammulina velutipes, Pleurotus ostreatus, and Lentinus edodes
were studied. VC were identified by gas chromatography-mass spectrometry (GC-MS) using
solid phase micro-extraction (SPME).
A storage study of 10 days was conducted in order to detect changes in VC and hence
deterioration in the different species. The C8 compounds present in all the studied
mushrooms were decreasing over time while aldehydes’ content was increasing. Furthermore,
sulphur compounds in shiitake, contributing to the overall deterioration of the aroma of fresh
mushrooms, were also increasing.
The quality of dried materials depends on the physical and chemical changes occurring as a
function of the processing conditions. Mushroom samples were dried at different
temperatures to determine the most suitable one for aroma development where shiitake
required 40 °C while chestnut needed 60 °C and enoki and oyster 50 °C. Some compounds
such as furfuryl alcohol, 2-undecanone and some conjugated dienal in chestnut and oyster,
pyrazines in enoki, and lenthionine in shiitake mushrooms were only generated via heat.
Rehydration temperature played an important role in the liberation of VC. In general the
maximum release of alcohols, aldehydes, pyrazine and conjugated dienal from the dried
material was higher at 100 °C rehydration temperature when compared to 25 °C.
The qualitative and quantitative composition of the VC can be used as quality indicator and
highlight the intensity of the processes in mushrooms in the course of processing and storage.