Direct conversion of waste loquat kernels to pigments using Monascus purpureus ATCC16365 with proteolytic and amylolytic activity

Abstract

Kernels of loquat (Eriobotrya japonica L.) fruits are rich in protein and starch contents; however, they have no significant application in world. This study was performed to produce pigments from Monascus purpureus ATCC16365 using loquat kernel powder (LKP) as a fermentation substrate and investigate the effect of four mineral salts (CaCl2, KH2PO4, MgSO4, and FeSO4) on pigment production in LKP-based medium. During the experiments, LKP was not subjected to any chemical or enzymatic hydrolysis, and it was tested directly as a substrate in shaking flask and fermenter cultures. It was found that addition of CaCl2 alone decreased red pigment production but did not cause an important change in synthesis of yellow and orange pigments. Supplementation of KH2PO4, MgSO4, or FeSO4 alone decreased the production of yellow pigment but increased the production of red pigments. When three salts (1.0 g/L KH2PO4, 0.3 g/L MgSO4, and 0.03 g/L FeSO4) were added together to the LKP-based medium, more productions of enzymes (protease and amylase) and red pigments were achieved. When experiments were performed in optimized medium (LKP and three mineral salts), maximum concentrations of red, orange, and yellow pigments were determined as 292, 193, and 171 AU/L in flask culture but 327, 241, and 204 AU/L in fermenter culture, respectively. Amylase and protease activities were 93.4 and 52.3 U/L in flask culture but 93.8 and 52.8 U/L in fermenter culture, respectively. This is the first report on the use of LKP as a substrate in production of enzymes and pigments from M. purpureus.