yeast cells were collected by centrifugation
(3600 g; 10min) and washed several times with distilled water to
remove excess reagent. All the treated cells were freeze-dried
at 54 C for 26 h by a vacuum freeze-dryer (MCFD5505, SIM
International Group Co. Ltd.). The dried biomass was grounded and
screened through a set of sieves to get different geometrical sizes
100e120 mesh. This produced a uniform material and the biomass
was stored in desiccators for future use.