Study On PEG Promoting Metabolism Of Extracellular Yellow Monascus Pigments And Production Activities And Preparation Of Edible Films

Monascus pigments,a group of nature pigments produced by Monascus spp.,including yellow,orange,and red pigments,are used as natural edible pigments with a long history in Southeast Asian countries.Recently,yellow Monascus pigments have attracted wide attention because of their high thermal stability,strong dyeing ability and a variety of biological activities.The current commercially water-soluble reduced yellow Monascus pigments are mostly derivatives produced by chemical conversion of red Monascus pigment,which are different from natural yellow Monascus pigments.At present,the research of water-soluble natural yellow Monascus pigments is still at the laboratory level.And their function is still unclear.Therefore,it has great market prospects to do the research on the enhancement of natural yellow Monascus pigments production,their functions and development of their potential applications.In this study,enhancement of water-soluble natural yellow Monascus pigments by Monascus ruber CGMCC 10910 was investigated.PEG-4000 was added to the fermentation broth and the effects on the bacteria growth and cell morphology of Monascus,as well as the pigments metabolism were studied.The results showed the mycelium content increased and the yield of water-soluble yellow Monascus pigments increased to 163.20 AU₃₅₀/mL by adding PEG-4000 at the initial stage.In addition,the mycelial morphologies,including the pellet size and hyphal diameter,were significantly influenced by PEG-4000.It was revealed that shorter,thicker and multi-branched hyphae were suitable for the formation of extracellular water-soluble yellow Monascus pigments.What’s more,it did not affect the composition of extracellular pigments,but changed the composition of intracellular pigments.In order to promote natural water-soluble yellow Monascus pigments in the market,the antioxidant activity of reduced water-soluble yellow Monascus pigments was compared with that of natural water-soluble yellow Monascus pigments in this study.It showed that natural pigments have higher antioxidant activity than the reducd pigments.Water-soluble natural yellow Monascus pigments inhibited the migration and invasion of breast cancer MCF-7 cells with no cell cytotoxicity.The antitumor effect is possibly associated with down-regulation of MMP-2 and VEGF protein expression.The cell line studies suggest that the fermented water-soluble natural yellow Monascus pigments could be selected as potential functional additives in further tests of breast cancer prevention and adjuvant therapy.Finally,the potential application of water-soluble natural yellow Monascus pigments in addition to be a colorant was explored.It was found that after addition the pigments into the edible films,the thickness,water content,water solubility,moisture permeability and light transmittance of the films decreased,while the tensile strength and elongation at break increased.The antioxidant activity of the films was significantly improved.Moreover,the color of the films significantly changed when they were treated with different pH buffer solutions.Therefore,water-soluble natural yellow Monascus pigments could be added to edible films as a natural antioxidant to increase antioxidant activity,and to monitor food deterioration on the same time.