Valorization of bakery waste for biocolorant and enzyme production by Monascus purpureus

• Fungal bioconversion for pigment production using bakery waste as feedstock.
• Bakery hydrolysate derived from Aspergillus awamori and Aspergillus oryzae.
• 1 g pigment/kg bakery waste was produced by M. purpureus fermentation.
• Glucoamylase and protease activities were 8 U/g and 117 U/g via SSF of bakery waste.

A concept of utilizing bakery waste as a nutrient source for the fermentative production of bio-colorant by Monasucus purpureus has been developed. The proposed ideas provide an innovative approach to establish a system or method to reduce the bakery waste problem encountered by Hong Kong or other countries. Bakery waste collected from bakery store was used in submerged and solid-state fermentation of Monascus purpureus to produce bio-colorant, which could potentially be applied in food and textile industries. The feasibility of utilizing bakery waste hydrolysate deriving from hydrolytic reactions by Aspergillus awamori and Aspergillus oryzae for fermentative pigment production was investigated. Preliminary data from bakery waste hydrolysate experiment presented that the highest pigment yield (about 24 AU/g glucose) was obtained with bakery waste hydrolysate containing 5 g/L initial glucose. Results from the solid state fermentation studies presented that the highest activity of glucoamylase and protease achieved was 8 U/g and 117 U/g respectively, at an initial moisture content of 55% and 65% respectively at 30 °C incubation temperature. The outcome from this study demonstrated that Monascus purpureus constitutes a promising host for bio-colorant and enzyme production using recovered sugars and amino acids from bakery waste.