The present study compared the amino nitrogen content and the antioxidant
activity of ‘Kochujang’ (K1) comprising white rice
‘Nuruk’ with those of five types of ‘Kochujang’
(K2-K6) comprising pigmented rice ‘Nuruk’ made by various strains
of fungi. After 90 days of ripening, the amino nitrogen content was higher in
the K2-K6 samples than in the K1 sample. The total polyphenol content was high
in K5, which comprised pigmented rice ‘Nuruk’ made by
Aspergillus niger (10.57 mg/g), and in K2, which comprised
pigmented rice ‘Nuruk’ made by Aspergillus oryzae
(9.19 mg/g). The total flavonoid content was the highest in the K2 sample (0.84
mg/g). The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activities of
the samples in the K2-K6 groups were 71.31%-79.63%, which were approximately 20%
higher than that of the K1 group. Overall, the
2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging
activity was also higher in the ‘Kochujang’ samples comprising
pigmented rice ‘Nuruk’ than in that comprising white rice
‘Nuruk’. The K2 sample had the highest superoxide dismutase
(SOD)-like activity (68.07%), and the K1 sample had the lowest SOD-like activity
(59.03%). However, there was no significant difference between K3, which
comprised pigmented rice ‘Nuruk’ made by Aspergillus
kawachii, and sample K5.