Free amino nitrogen (FAN) was analyzed according to the European
Brewery Convention Method (EBC, 1987) with modification.
150 mg of rawand extruded DCF was mixed with 1.5 mL of distilled
water in a 2 mL micro centrifuge tube, vortexed and then centrifuged
at 12,000 g for 20 min using a micro high speed centrifuge
(Micro 17TR, Hani Science Industrial Co, Ltd., Korea). One mL of
supernatant was mixed with 1mL of Ninhydrin color reagent and it
was heated in boiling water bath for 16 min. The tubes were
transferred to a cold water bath and 5 mL of dilution reagent was
added, mixed and the absorbance was read at 575 nm against a
blank containing 1 mL of water in place of the sample.