Experimental Research On The Pilot Plant Fermentation Process

Complex fermentation agent is a kind of active bacterium agents which is used for fermenting dough before steaming steamed bread.The experimental group has determined that the complex fermentation agent is composed of four kinds of fungus and bacteria:Saccharomyces cerevisiae（N）,Hansenula anomala（H）,Lactobacillus acidophilus（S）and Lactobacillus paracasei（G）.Complex fermentation agent produces a lot of flavor substances in the process of making the dough.Compared with the dry yeast which is composed of the single bacteria,the steamed bread with complex fermentation is obviously improved in color,taste and fragrance.In this study,the cultural medium was improved on the basis of the original method.And the cultural time,the cell acquisition process,the granulation process and the drying process were optimized.In this study,we processed the insoluble matter of the corn steep powder,which is the organic nitrogen source and the recipe of the cultural medium was determined:corn steep powder 1%、glucose 2%、（NH₄）₂SO₄ 0.5%、K₂HPO₃ 0.3%、MgSO₄ 0.06%、MnSO₄ 0.02%、sodium acetate 0.5%、Citric acid hydrogen diamine 0.2%。Seed cultivation method:Saccharomyces cerevisiae（N）:YEPD liquid medium,one level seed fluid 200ml,30℃,150r/min for 24h;two level seed fluid,1000ml（0.5%）,30℃,150r/min for 24h;Hansenula anomala（H）:YEPD liquid medium,one level seed fluid,200ml,30℃,150r/min for 16h;two level seed fluid,1000ml（0.5%）,30℃,150r/min for 24h;Lactobacillus acidophilus（S）and Lactobacillus paracasei （G）:MRS liquid medium,one level seed fluid,200ml,37℃,static culture for 48h;two level seed fluid,3000ml（1.5%）,37℃,static culture for 48h.The culture time and culture conditions of 300L fermentor were determined:Saccharomyces cerevisiae should be inoculated at the beginning of culture,by 25℃,the stirring speed 150r/min,the ventilation rate was 4～5v/v·min,pH6.0.Hansenula anomala,Lactobacillus acidophilus,Lactobacillus acidophilus should be inoculated by 7 hours after the beginning.And supplement 2%glucose,pH6.0,the ventilation rate was 2～3v/v·min,culture for next 9 hours.We studied the collection of cells and the addition of granulation materials.The process was determined:after the fermentation,get clean creamy cells mud through the tube centrifuge 16000r/min and get the mud washed three times and adding 2%of the Secretary 60 in the last washing.There are two methods that wet particle can hold the powder and be non-sticky:Add 12%of the starch as the ingredients mixed with the mud by steel mesh granulation,or add 50%of the starch mixed into the mud by twin-screw extrusion granulator granulation.The temperature of dryness of the wetting particle should be set at 30℃and kept for 30min.The above conditions can ensure the high survival rate and quality of the product.Sensory evaluation between two kinds of steamed bread,one with finished product and one with activated dry yeast sold in markets is done in this paper.And it provides a full set of process and operation instructions.The cost and profit margins including the cost of materials,water,electricity power,human resource Etc.,were accounted.Its profit rate will be around 23.84%.