Abstract:

In this study, the main components (protein, carbohydrate, crude fat, and total phenol), color, ash and volatile
components of the edible mushroom Pleurotus eryngii were monitored after hot air drying (HAD), vacuum freeze drying
(VFD), heat pump drying (HPD) and vacuum microwave drying (VMD) to unravel the effects of different drying methods
on the quality and volatile components of the mushroom. It was found that the contents of ash and protein of dried P. eryngii
by four drying methods changed only slightly, while the content of carbohydrate (13.56%) was the lowest in P. eryngii
dried by VMD, while the VFD-dried sample had the lowest contents of total phenol (39.97 μg/g) and crude fat (1.27%) but
it exhibited the least color changes. The changes in trehalose, an abundant monosaccharide in P. eryngii, caused by four
drying methods were in the order of HPD > VFD > HAD > VMD, while the changes in mannitol content caused by these
drying methods were in the order of HPD = VFD > HAD = VMD. The changes in volatile composition of P. eryngii caused
by four drying methods were also analyzed. A total of 68 volatile compounds were detected, including aldehydes, alcohols,
esters, ketones, hydrocarbons and others. The most abundant compounds of P. eryngii dried by HPD, HAD and VMD were
all aldehydes, including isovaleraldehyde, caproaldehyde and 2-methyl butanal. However, alcohols were the major volatile
compounds including 1-octen-3-ol in the VFD-dried sample, which also contained esters, ketones, alkanes and pyrazines,
together with small amounts of other compounds. Among these drying methods, more volatile compounds with lower
thresholds were generated by heat treatment methods due to the interaction of compounds in the raw material. From these
findings, it was found that among the four drying methods, VFD could optimally maintain the quality of P. eryngii while
HPD method gave better results for its economic and stable characteristics.

Key words: Pleurotus eryngii, drying method, quality, volatile component