Red pigment production by Monascus purpureus using sweet potato-based medium in submerged fermentation

Monascus pigments have potential application as natural colorants in food industries. Sweet potato-based medium was optimised by statistical methods for maximised production of water-soluble red pigment from Monascus purpureus. Significant medium components (sweet potato, K2HPO4 and MgSO4·7H2O) were identified by employing a Plackett-Burman screening experiment for pigment and biomass production. A five-level central composite design of the response surface method was applied to evaluate the optimal concentration and the interaction effects between the selected components. Maximum pigment absorbance of 4.488 (ODU/ml) was predicted at the optimum level of sweet potato, 3.341%, K2HPO4, 0.082% and MgSO4·7H2O, 0.033%. Model verification was performed at the predicted optimal level and the model was well fitted with the experimental results. The results of this study showed that sweet potato can be utilised as a low-cost substrate for red pigment production.