PCL assay, based on the photo-induced chemiluminescence of
luminol, was carried out according to the procedures reported by
Zhang et al. (2014) using a PHOTOCHEM device (Analytic Jena
AG, Jena, Germany) with minor modifications. Briefly, 2.3 mL of
reagent 1 (sample solvent), 0.2 mL of reagent 2 (reaction buffer),
25 lL of diluted reagent 3 (luminol), and reagent 4 (trolox) were
mixed together for the calibration curve. Then reagent 4 was
replaced by a sample solution to measure the antioxidant activity
of the sample. In this system, luminol was used as a photosensitiser
which generates superoxide radicals and a chemiluminogenic
probe for free radicals. The antioxidants activities were quantified
based on their inhibitory effect on luminescence generation and
were expressed as lmol trolox equivalent/g quinoa (lmol TE/g)
(r
2 = 0.996