After 7 d of incubation, the substrate
was dried on aluminum foil at room temperature and ground to a fine powder
using a sterile household grinder. Pigment was extracted following the procedure
of Babitha et al. (8). In brief, fermented solid substrate was extracted with
5 mL of 90% methanol per gram of dry fermented substrate (gdfs). The mixture
was placed on a rotary shaker at 200 rpm for 1 h, allowed to stand for 15 min, and
filtered through Whatman #1 filter paper.
Following the method of Tseng et al. (12), extracellular pigment was quantified
by measuring OD at 412 and 500 nm, representing yellow and red pigment
production, respectively and pigment yield was expressed as OD/gdfs. Absorbance
was also measured for pigment extract