Application of thermal stability difference toremove flammutoxin in fungalimmunomodulatory protein, FIP-fve, extract fromFlammulina velutipes

Fungal immunomodulatory protein (FIP-fve) is a potential functional food ingredient.However, undesirable component flammutoxin (FTX) would occur in the extracted fractionof FIP-fve. In this paper, an application of heating processing instead of the intensiveseparation process was employed in fractionation of FIP-fve, meanwhile, exclusion of FTXwas reached. Contents of FIP-fve and FTX were monitored by HPLC-UV-ESI-MS. Both FIPfveand FTX had higher thermal stability in a lower concentration solution. Cold watercould effectively extract FIP-fve and FTX from fresh mushroom without acetic acid anddisulfide-bond breaking agent b-mercaptoethanol commonly used in biochemical studies.Heating cold water extract contained 580 mg/mL FIP-fve and 452 mg/mL FTX at 60 _C for5 min could effectively exclude FTX and remain 75% of FIP-fve. Adding 0.1 M trehalose or20% ethanol did not significantly alter the stability of both proteins. The method developedis an applicable procedure for preparing FIP-fve solution free of FTX.