The experiments were conducted in 250 mL Erlenmeyer
flask covered with cotton plugs to facilitate air transfer.
The substrates containing RSC and wheat bran, which is
beneficial for microbial growth, were sterilized subsequently
at 121°C for 20 min, cooled and inoculated with
3 mL spore suspension (1 × 107 spores/mL) of A. niger,
an uninoculated flask served as control. The samples in
flasks were incubated at 30°C for 72 h. After fermentation
was completed, inoculated samples were dried at
65°C for 48 h, cooled and ground to pass a 40-mesh sieve
for related index determination. Three replicate were prepared
for each treatment. All treatments were carried out
in two sets.