Study On The Production Optimization Of Lipopepetide From Bacillus Subtilis And Application In Bread

Biosurfactants,with lower toxicity and biodegradability,an alternative of chemically synthesized surfactants,has been widely used in food and chemical industry.Lipopeptide,not only has the effect of good emulsifiability,antibacterial activity,but also has the effect of solubilization and humidification,has been used in many commercial areas such as petroleum,pharmaceuticals,biomedical,and food processing industries.Generally,lipopeptide was produced by microorganism.However,with a lower output and a difficult extraction and separation process,it cannot meet the demands of modern industry production.This study investigates that alternative medium options are being sought to improve the production of lipopeptide produced by Bacillus subtilis ATCC21332 with relatively accessible and low-cost raw materials.In addition,by studying the substrate utilization and detecting the concentration of amino acid on the optimal fermentation conditions of Bacillus subtilis ATCC21332 can provide theoretical basis for the medium optimization of Bacillus subtilis ATCC21332.In order to further explore the physicochemical properties of lipopeptide,adding lipopeptide to bread,and studying the effects of lipopeptide on the characteristics of baking bread dough and storage effect and further to determine the best dosage of lipopeptide,so as to provide a new idea for the industrialized production of the biosurfactant and the lipopeptide as a new food additive.The main research results are as followings:It turns out that the production of lipopeptide was up to 4885 mg/L under the optimization condition that the soybean meal as the substrate of 40 g/L,glucose concentration of 7 g/L,incubation volume of 5%,the dissolved oxygen content of 120 ml(per 500 ml flask),which increased by 35.7% enhanced production of lipopeptide by Bacillus subtilis ATCC21332 when compared with the yield of lipopeptide 3600 mg/L before.In addition,by detecting the contents of amino acids on the fermentation of Bacillus subtilis ATCC 21332,the contents of glutamate increase dramatically at 81 h,and also the surface tension of fermentation broth decrease from 24 to 15 mN/m.By addition of the specific amino acids to the medium,the yield of lipopeptide was increased by different extent,among of which is the glutamate that have the maximum yield of lipopeptide up to 954 mg/L,which is 7 times content of the control,which also give us an insight of the prospect that lipopeptide can be used in the area of food and other fields.By comparing the specific volume and texture of different lipopeptide addition on the bread,namely the contents of lipopeptide is 0.1%,0.2%,0.3%,0.4%,0.5%.With the increase of lipopeptide contents,the specific volume of the bread increased first and then gradually began to decrease,and hardness of bread core decreased gradually and then increased slightly,and the springiness and adhesion increases and then decreases gradually.When the content of lipopeptide was 0.4%,the specific volume of bread was 7.04 mL/g,which increased by 16% compared with the control,and the hardness of the bread core was 95.9 g,and also with a maximum of bread springinessIn order to study the antiaging effects of lipopeptide on the bread,the research compares the effects of different lipopeptide additives on the bread texture,moisture migration and retrogradation.It turns out that with the increase of lipopeptide,bread hardness decreased gradually,and moisture migration of the bread core decreased first and then increased gradually.When the content of lipopeptide was 0.4%,the moisture migration of bread core and bread surface was lower than that others.With the extension of storage period,the retrogradation of bread increased gradually.When the lipopeptide contents was 0.4%,the retrogradation value of bread was lower than that others.The bread retrogradation value is 0.479 J/g at first day,which is lower than that of the control by 11.79%.,and also the bread retrogradation value is 1.727 J/g at the seventh day which is lower than that control by 21.93%.In order to study the effects of lipopeptide on the bread shelf life,the research study the moisture activity by comparing the lipopeptide additives of 0.2% and 0.4%.It turns out that the water activity of the bread was lower than that of the control,and the more concentration of lipopeptide added,the lower the water activity of the bread epidermis.When the content of lipopeptide was 0.4%,the water activity of bread surface reached 0.864,which was lower than that of the control 4% at 7 days.