Dissertation
Dissertation > Industrial Technology > Light industry,handicrafts > Food Industry > The dairy processing industry > A variety of dairy > Fermented dairy products

The High-activity Concentrated Bifidobacterium Bifidum Yogurt Starters Made by the Vacuum Freeze-drying Technology

Author ChenTao
Tutor TianRuiHua
School Inner Mongolia Agricultural University
Course Fermentation Engineering
Keywords Bifidobacterium bifidum Domestication Concentrated fermentation agent Vacuum freeze-drying Protective agent
CLC TS252.54
Type Master's thesis
Year 2011
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With the improvement of people 's health awareness , yogurt with prebiotic effect of Bifidobacterium been recognized . The positive development of great significance for the promotion of the the yoghurt culture production levels and the fermentation of the rapid development of the dairy industry has independent intellectual property rights Bifidobacterium efficient concentrated yogurt freeze-dried fermentation agent . This paper is using vacuum freeze-drying technology to explore the production of high- activity concentrated Bifidobacterium yogurt freeze-dried fermentation agent , good fermentation performance Bifidobacterium bifidum aerotolerance acidproof domesticated and freeze-drying process is the focus of this study . After by many aerotolerance acidproof domesticated one pair of oxygen and acid tolerance strains of Bifidobacterium bifidum not mutate . 3L and 10L fermenter liquid medium to PTYG , contrast studies of the impact of expanding culture inoculum and medium volume , the results show that : at a pH of 6.5 to 7.0 , medium volume fermenter volume 4 / 5 inoculation amount of 5 % , 37 ° C under the conditions of culture 12 hours harvested bacterial number reached about 7 × 10 9 cfu / mL . Using orthogonal experiment measured the best conditions the Bifidobacterium bifidum purebred fermented milk : the initial pH of 7.0 , inoculum size 6% , 5% of the optimum sucrose dosage , incubation temperature was 39 ° C , 4 to 5h between curd, detecting the number of viable cells can reach more than 10 9 cfu / mL . By studying the number of revolutions of the centrifuge , the the centrifugation time influence of the the Bifidobacterium bifidum centrifugal loss rate , determine the best centrifugal conditions for the room temperature 6000r/min , 10min, recovery rate of 97% . Single factor test and orthogonal design the selected dichotoma Bifidobacterium Yin Lyoprotectant different concentration experiments, 20% trehalose 8 % skim milk, 5% glycerol composite protective agent adjusted to pH 6.5 ~ 7.0 lyoprotectant as Bifidobacterium bifidum , the thickness of the lyophilized bacterial suspension 0.75cm, 4 ° C refrigerated bagging seal after the sample was lyophilized to remove the crushed . The simultaneous detection lyophilized survival of 80%, and the number of viable cells is about 4.4 × 10 10 cfu / g . Lyophilized fermentation agent at atmospheric pressure of 4 ℃ preserved after 6 months , the number of viable cells as well as the fermentation activity are no significant changes to exhibit relatively stable storage properties , with good results.

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