Abstract:
Objective Key functional components and in vitro antioxidant activities of 4 types of Hongqu (Monascus-rice fermentation paste) were determined for product development.
Method Color value, monacolin K (MK), γ-aminobutyric acid (GABA), ergosterol, and polysaccharide of Functional Qu (FQ), Coloring Qu (CQ), Wuyi Qu (WQ), and Gutian Qu (GQ) were measured by means of UV-Vis, colorimeter, and HPLC. Antioxidant activity of the Hongqu was determined by in vitro chemical assays including the ferric ion reducing antioxidant power (FRAP) and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS) radical scavenging capacities. Correlation between the functional components and the antioxidant activities of Hongqu was analyzed using SIMCA and SPSS software.
Result The Hongqu specimens varied in the following aspects. CQ was measured significantly higher on orange, yellow, and red color value than FQ, GQ, and WQ, while GQ on orange, yellow, and red color value than FQ and WQ, and FQ on orange color value than WQ. FQ contained significantly more MK than CQ, GQ, and WQ, whereas WQ significantly more GABA than CQ, FQ, and GQ, but WQ and FQ significantly more ergosterol than CQ and GQ, and FQ had the highest content of polysaccharides, which was followed by CQ. The FRAP and DPPH and ABTS scavenging abilities of CQ were significantly higher than those of FQ, WQ, and GQ, and FQ was stronger in FRAP than WQ or GQ. The color value of Hongqu positively correlated with FRAP (0.733 ≥ r ≥ 0.703) and negatively with the scavenging 50% DPPH (−0.896 ≤ r ≤ −0.880) and ABTS (−0.773 ≤ r ≤ −0.758). It appeared that pigment was the critical antioxidant components in the Hongqu. On the other hand, neither MK, GABA, ergosterol, nor polysaccharides significant correlated with the in vitro antioxidant activity of the 4 Hongqu.
Conclusion An extremely significant correlation between the pigment and antioxidant activity were demonstrated in CQ more than the other 3 Hongqu. In the development of natural antioxidant products, Monascus pigment could be a viable potential candidate.