Study On Enrichment Of ?-tocopherol From Coix Seed Fermented By Monascus Purpureus

?-tocopherol is the most abundant and active form of vitamin E,which mainly found in vegetable oils.It has many physiological functions such as anti-oxidation,anti-aging and procreation.?-tocopherol,as a nutritional supplement and antioxidant,is particularly effective in hot food processing and has a wide application prospect because of its good heat resistance.At present,?-tocopherol mainly comes from the extraction distillation or chemical synthesis of vegetable oils,which have some problems such as difficult extraction,low purity,high cost efficiency and low safety.The other method called Enzyme catalysis also has the problems of complex technology and difficult popularization.In order to obtain a simple,safe,efficient and low-cost method for microbial fermentation and enrichment of ?-tocopherol,this study intends to use Monascus purpureus to ferment coarse cereals to filtrate the high-quality matrix for producing ?-tocopherol on the basis of previous scientific research.The fermentation conditions were optimized by response surface experiment to achieve the high-efficiency enrichment of ?-tocopherol;Meanwhile,the dynamic monitoring of the fermentation process was carried out to establish a fermentation kinetic model for promoting the enrichment of tocopherol in solid state fermentation of Monascus purpureus.The molecular mechanism of its efficient enrichment was preliminarily explored based on the transcriptome analysis of Monascus purpureus.The main research results are as follows:(1)Screening of coarse cereals matrix:coix seed,Tartary buckwheat,buckwhea,quinoa 4 kinds of grain all contain rich nutrition component,the protein,fat and total sugar in coix seed were significantly higher than other cereals.Using coix seed as the fermentation substrate can provide sufficient nutrients for the growth of Monascus purpureus,and the coix seed grains after gelatinization are evenly dispersed without adhesion,which is more conducive to the growth of Monascus purpureus.The three kinds of tocopherol were all detected in coix seed,tartary buckwheat,buckwheat and quinoa.All 4 kinds of cereals contain three kinds of tocopherol,the content of ?-tocopherol is the highest among them.And four kinds of coarse cereals fermented by solid fermentation of Monascus purpureus also have three kinds of tocopherol which increased significantly and the content of ?-tocopherol was the highest among them(P<0.05);The yield increased by 6.68 times after fermentation(P < 0.05)which coix seed was used as the substrate,and the fermentation products obtained the highest color value(1333.03 U/g),significantly better than other cereals(P < 0.05).Therefore,it can be used as the optimal fermentation substrate for subsequent research.Monascus purpureus grows vigorously on coix seed substrate,and its color is brilliant.The coix seed red yeast powder harvested after fermentation had the best sensory evaluation,the highest color value,and the high enrichment of tocopherol.Therefore,it can be used as the optimal fermentation matrix for subsequent research.(2)The fermentation process parameters were optimized by Monascus purpureus with the fermentation substrate of coix seed.Through the product accumulation dynamic tracking,it was concluded that the optimal harvest time of ?-totocopherol was the 10 th day of fermentation.According to response surface optimization,the optimal fermentation parameters were: the ratio of material to liquid was 2:1,the inoculation amount of Monascus purpureus was 15 %,the fermentation temperature was 28?,and the fermentation time was 10 days.The yield of ?-tocopherol was up to 12.414 mg/m L,which was 3.99 times higher than before,and the color value increased to 1458.26 U/g,which was 1.09 times higher than before.On the basis of optimizing the process,the growth kinetics,the kinetics of ?-tocopherol production and the kinetics of total sugar consumption of the substrate were constructed,and the fitting effect of the model was good.The fermentation type of the synthesis of tocopherol belongs to the growth part coupling type,which product production is proportional to cell growth but time delay by model analysis.This provides a theoretical basis and reference for the management of fermentation process,metabolic regulation,target collection and continuous fermentation.(3)Study on the mechanism of enrichment of coix seed in solid state fermentation of Monascus purpureus based on transcriptome: In GO classification,biological process category accounts for the largest proportion,and the main gene functions include cellular process and metabolic process.Cell and some cell genes are the most important functions of cell components,which are mainly manifested in binding and catalytic activity.The KEGG classification included 31 metabolic pathways,and the metabolic pathway of Unigene sequence in the category of metabolic account for a large proportion,mainly including carbohydrate metabolism,metabolism of cofactors and vitamins,and energy metabolism.Based on the analysis of GO and KEGG enrichment,the synthesis and accumulation of ?-tocopherol may be affected by metabolic pathways such as tyrosine,tryptophan and phenylalanine biosynthesis,which mainly involved gene ID and up-regulated multiples are: c4955-g1(1.156),c5440-g7(1.1826),and c4553-g1(1.2051).In the process of tyrosine synthesis,the up-regulated expression of related genes leads to the increase of tyrosine content,which further promotes the increase of 4-hydroxyphenylpyruvate and hemogentisate as precursors of the ?-tocopherol synthesis pathway.This process is accompanied by a series of oxidordeuctase and sulfotransferase,which jointly promote the metabolic synthesis to ?-tocopherol.