The Main Bacterial Flora In Traditional Starter Culture Influence On The Flavor Of Chinese Steamed Bread

Based on the traditional steamed bread starter cultures(traditional Jiao Zi) as the research object, the reference and the research status of traditional culture at home and abroad, mainly studied the traditional Jiao Zi fermented dough fermentation characteristics, volatile flavor composition and traditional Jiao Zi main bacteria isolation and identification bacteria powder production and compound bacteria influence on the volatile flavor of steamed bread.1. Through the study of traditional jiaozi fermentation characteristics of fermented dough has been under four different sub-amount of yeast dough fastest, PH value 6-9h fermentation stage gas production rate between 5.81-4.35, 1.73-7.33 pH value and in a stable fermented dough. Experimental results show that the steaming bread by 8.5±0.5h in sensory evaluation of the total highest score, so it can be 8-9h this stage as the end of fermentation is complete.2. Through the single factor experiment, orthogonal experiment and verification after fermentation sub main process parameters optimization bread: yeast child dosage 8g, flour200 g, fermentation temperature 35℃, relative humidity of 85%, fermentation time 8h, add water 45%, 12 the number of tableting, the second proofing time 40 min.3.By Solid phase micro-extraction method were determined by GC-MS of the traditional jiaozi and dry yeast bread sub volatile flavor compounds, comparative analysis showed that cause yeast bread flavored with traditional jiaozi bread reasons for the differences: 1,The presence of species and the relative percentages of both in the same category volatiles significant differences, and the relative percentage of species shared the same category there are also significant differences. 2, both of which will have its own unique volatility materials:1-methylnaphthalene, 1,3-dimethylnaphthalene, 2,6-ditbutyl-1,4-benzoquinone and other aromatic substances, ketones are acetophenone yeast bread unique flavor substances;1-heptanol, 1-octanol and other alcohols, ethyl decanoate, ethyl benzene, acetaldehyde,formaldehyde, furan and other traditional yeast bread child specific volatile flavor compounds.4. Separated from the traditional yeast to give the child identified two lactic acid bacteria and a yeast, lactic acid bacteriaⅠ, lactic acid bacteria Ⅱand yeast strains; by contrast morphological analysis and gene sequencing of lactic acid bacteria Ⅰ, lactic acid bacteria Ⅱand yeast microbial strains species identification, the three strains were identified as Pentosaceus, Lactobacillus brevis and Saccharomyces cerevisiae. After single factor and orthogonal experiment yeast powder dosage 6g, pentosaceus of 2.5g, 0.5g Lactobacillus brevis is best when steamed sensory quality, so as a complex powder formulations. Volatile flavor compounds than the results show: a single powder yeast bread(JJ), pentosaceus powder and yeast bread(WJ), Lactobacillus brevis and bread yeast powder(DJ), complex powder bread(FJ) volatile flavor ingredients show: comparison with JJ showed WJ:pentosaceus can be added to produce cis-4-dec-1-ol, isobutanol, hexanal, nonanal,furaldehyde, isovaleraldehyde, isobutyl phthalate, propyl heptyl bit lactone, ethyl caproate,linoleic acid ethyl ester, 1-methyl naphthalene and naphthalene, acetic acid and the like.Comparative results show DJ and JJ: Lactobacillus brevis is added to produce butanol, nonyl aldehyde, hexanal, phenyl acetone, ethyl benzoate, ethyl valerate, 2-methyl-2-methyl-butyric acid propyl and other volatile substances; FJ contrast with JJ showed: bread compound powder capable of producing 1-heptanol, cis-4-decene-1-ol, furan formaldehyde, hexanal,nonanal, isovalerate had ester, isobutyl butyrate, ethyl, iso-butyl phthalate, ethyl benzoate,naphthalene, 1-methylnaphthalene and other aromatic substances.5. Using Commercial strains for distribution of bacteria powder flavor: single dry yeast fermentation of steamed bread were detected 38 kinds of volatile substances, compound bacteria in fermented steamed bread powder 54 kinds of volatile substances detected.Composite powder bacteria fermentation steamed bread can produce 1- nonyl alcohol, 1-1-octanol, heptanol, 2-4- methyl ethyl- amyl alcohol, shun- 4- decyl ene- 1- alcohol, furfural,tridecane acid ethyl ester, tetradecanoic acid isopropyl ester, phthalate butyl ester,heptadecanoic acid methyl, propyl benzene, naphthalene and 1- methyl naphthalene, 2, 6-2tertiary butyl benzene quinone, acetic acid and volatile flavor materials such as 2- methyl butyric acid.