The Effect of Drying Methods on Metabolites Change in Ganoderma lucidum

Ganoderma lucidum have been called as ‘Lingzhi’ in China, ‘Reishi’ in Japan, and ‘Yeongji’ in Korea and reported to possess excellent nutritional value due to high protein and essential amino acid. Not only this, Ganoderma lucidum have been used as medicinal purpose by their bio-active compounds such as polysaccharides, essential oil compounds, and ganoderic acids. Many investigations of Ganoderma lucidum were performed but, these were focused on biological activities (anti-oxidant, anti-inflammation, anti-bacterial, anti-microbial, and anti-cancer) of phytochemicals from dried-samples. In this study, we expected that methods for drying could affect to metabolites of Ganoderma lucidum. Therefore, two different conditions of drying (60°C: heat-drying; ‒ 80°C: freeze-drying which removes damage of their physical structure) were subjected into this experiment. GCQTOF-MS (LECO Pegasus GC HRT; Leco Corp., St. Joseph, MI, USA), and UPLC-QTOF-MS/MS (Agilent series 1290 UPLC-QTOF instrument; Agilent, Waldbroon, Germany) were performed to analyze primary, and secondary metabolites. In results of primary metabolites from GC-QTOF-MS, most analyzed amino acid group compounds, one of the valuable sources of functional food, including alanine, valine, proline, phenylalanine, isoleucine, serine, threonine, lysine, and glutamine showed significantly increased in heat-drying (60°C) than freeze-drying (‒ 80°C) but other compounds did not show significant difference between drying methods. On the other hand, in results of secondary metabolites from UPLC-QTOF-MS/MS analysis, the main phytochemicals (21 triterpenoid compounds), were analyzed and 9 compounds out of 21 (ganoderic acid X, ganoderenic acid B, lucidenic acid E, ganoderic acid F, ganoderic acid A, ganoderenic acid D, lucidenic acid A, ganoludidic acid A, and ganoderic acid E) were significantly decreased in heat-drying (60°C) following student’s t-test. These ganoderic acid derivatives are known to be associated with immune system regulation and plays important role as tertiary valuable sources for functional food involved in pharmacological function relative to human body. In conclusion, it is important to set the drying method according to the desired compounds either amino acid or ganoderic acids, and values either nutritional value or pharmacological value.