Study Of Microecology Dynamic Change And Inoxidizability In The Process Of Post-fermentation Of Mucor-Type Douchi

Douchi is one of the four traditional Chinese fermented food, historically, has been loved by people. The production of mucor-fermented douchi is the largest in similar products and it has the richest characteristic, it is steamed soy insulation after starter-making with mucor and anaerobic fermentation to get products with special flavor and product form, its rich nutrition, unique flavor, is rich in protein, amino acids, small molecules, peptides, soy isoflavones, and other health care function, at the same time also can increase appetite. After this article through to study the process of mucor-fermented douchi post-fermentation, the micro ecological changes in volatile composition, free amino acid, antioxidative peptide content change and using nuclear magnetic resonance (NMR) technology to test the sample analysis, get the following conclusion:1.After using PCR-DGGE analysis the process of mucor-typedouchi post-fermentation, microbial communities in the process of dynamic change; we can conclude that the main bacterium are pseudomonas bacteria and red spirillum, they are the main advantage bacterium in the process of post-fermentation.2.By using solid phase microextraction gas-mass spectrometry to study the process of mucor-fermented douchi post-fermentation, in different periods after the volatile components were analyzed, and through the retrieval and access to documents identified in the fermentation process after the main volatile flavor substances, including alcohols(16), esters(19), aldehydes (9), acids(6), ketones (10), phenol(2), alkane(7), and heterocyclic compounds(1). Through principal component analysis (pea) is analyzed at the same time, and3-methyl-1-butanol,(S)-2-nitro1,2-propylene glycol, ethanol,1,3-butanediol, lavender, alcohol, benzene, formaldehyde, butyl aldehyde acetal,2-symplectic acetylenic acid, isobutyric acid isoamyl acetate, isoamyl butyrate, ethyl hexanoic acid methyl ester, decanoic acid,2-heptanone,5-methyl-3-hexanone,3,5-dimethyl-4-heptanone,2-2-dodecane methadone, decyl ketones,2-nonadecane,1-chloro-2-bromopropane, undecane, ring dodecane,(1-) ethyl propyl benzene, nonanal, ethyl caproate,2,3-butanediol, hexyl alcohol,1-octene-3-alcohol,2-ethyl hexanol, ethyl butyrate,3-hydroxy ethyl butyrate,3-methyl-2-pentanone, vinyl-4-2-methoxy phenol and guaiacol has the bigger contribution in the process of mucor-fermented douchi post-fermentation,, and the content of compound increase gradually.3.Through to analyse the content of amino acid, we can concluded that amino acid nitrogen, free amino acid and total acid content have been keep increasing trend in different periods of the fermentation process, the early period of post-fermentation because of a variety of enzyme activity is higher, metabolism of organic acid on the enzyme activity inhibition is less, flavor amino acids, hydrophobic amino acid content increased significantly, so that the amino acid nitrogen content will keep the increasing trend, around15days,it reached the maximum.the content of essential amino acids has remained in the process of rising trend;The later period,due to organic acids and acidity increased, the protease enzyme activity is reduced, the hydrophobic amino acids generated rate gradually slow down, the growth of the essential amino acids speed became slow, lead to the produce rate of amino acids nitrogen is slower, about20days,amino acid nitrogen content in the fermentation flatten out no longer growth, this illustrate that douchi has mature basically in20days.4. Through study antioxidant peptide and its inoxidizability in the process of mucor-type douchi post-fermentation,show that with the fermentating, proteins was decompose constantly into peptides and amino acids and other substances, molecular weight which below3KDa its content of antioxidant peptide gradually increased, the inoxidizability roughly keep the increasing trend along with fermentation, shows its good oxidation resistance. Molecular weight which below3-10KDa,the amino acids which has oxidation resistance constantly present on C and N extremity of peptide fragment,its oxidation resistance has been keep increasing trend. Molecular weight which above10KDa,because of it was broken down into small molecular peptide, its content has been reduced, the oxidation resistance has also been droped.5. By nuclear magnetic resonance (NMR) technology for mucor-fermented douchi in different periods of post-fermentation, from component content, with the increase of fermentation days, content of bound water reduce continuously, can indirectly reflect as the extension of fermentation time, macromolecular protein in douchi gradually breaks down, the water in cells exist mutual transformation (T22and T23), free water content has decreased to a certain extent.