Anti-oxidant Properties of the Water-Soluble Fraction Obtained from Monascus Fermented Jatropha Seed Cake

Abstract

A non-edible plant, Jatropha curcas, is useful for biodiesel production due to rich oil content in the seed. However, deoiled seed residues, seed cake, have not yet been effectively utilized so far, even though it is rich in protein. In this study, we explored suitable strain of genus Monascus to advance anti-oxidant capacity of the Jatropha seed cake, and investigated the chromatogram profiles to find characteristic peaks. Sun-dried Jatropha seed cake was defatted, adjusted to 70% moisture, and used as a culture substrate in a solid-state fermentation for Monascus fungi. Water-extract of Jatropha seed cake fermented with M. purpureus NBRC31842 out of 30 strains of genus Monascus showed the highest anti-oxidant activities, about 3-fold higher than those of non-inoculated control, in both oxygen radical absorbance capacity (ORAC) assay and l,l-diphenyl-2-picryl-hydrazyl (DPPH) assay. The profiles of products generated by M. purpureus NBRC31842 fermentation at.30D C .for 14 days were investigated using reverse-phase C18 HPLC column chromatography. Almost all peaks detected in the water-extract of non-inoculate control were confirmed in the Monascus fermented Jatropha seed cake, and we found that some of them were enhanced by fermentation. In addition, these peak areas increased in the water-extract of Monascus fermented seed cake, which means that Monascus fungus degrade abundant protein in the Jatropha seed cake during fermentation, and increase the anti-oxidant peptides. These results suggest that the fermentation of Jatropha seed cake, by-product of biodiesel production, by Monascus fungi might contribute to advance of anti-oxidant capacity, and it may be useful as a livestock feed.