| With the study in multipurposly exploiting and using agricultural byproducts and the wasteresidue during the manufacture of industry and agriculture more and more thoroughly inworldwide,the study in deeply processing agricultural products in our country was paidattention gradually,especially the research in using some agricultural byproducts which havethe comparatively high output and cheap cost to produce some products that can be sold withhigh price was attaching importance to more and more people.In this paper,the study of theinfluence to the raw material by pretreatment,the mutation breeding ,the influence elements ,condition to the fermentation and producing citric acid from apple pomace which annualyield is very high in our province ,even in our country, by the method of Aspergillus nigersolidstate fermentation was carried on systemly.The results were followed: 1. The influce to the content of reducing sugar in apple pomace with different pretreatment.The study of the influence of four different pretreatment-hightemperaturetreatment,hydrolysistreatment, cellulose enzyme treatment and fungi treatment to the content of reducingsugar was carried on, the results showed:(1) The content of reducing sugar was increasedunnotably after the treatments of high temperature . Comparatively high temperature(121℃)and short time(40min,60min) treatment,the content of reducing sugar in apple pomace showedthe tendency of decline;relatively low temperature(100℃,114℃) and long time(80min)treatment,the content of reducing sugar in apple pomace appeared to increase,but the changerange of the content of the reducing sugar in apple pomace which caused by high temperaturewas not high in the whole.(2) After apple pomace hydrolyzed, the content of reducing sugarincreased obviously in hydrolyte, moreover,the content increased with the time rised.When theproduction industrialized, if hydrolysis pH=1,T=121℃,20min is the relatively suitable time.(3)After the apple pomace was degraded by three kinds of cellulose enzyme,the content ofreducing sugar in apple pomace increased notably also.Among three cellulose enzyme,theresult of enzymolysis of 3# enzyme was best.(4)When used fungi to degrade the apple IIIpomace,if the 21strains of fungi which be selected in the study,11 strains could grow in pureapple pomace and FG03, FG07, FG10, FG11 could degrade the apple pomace effectively,among those,FG03 was the best. 2.The results of selecting uncultivated fungi which could produce citric acid in highefficiency.In this study,the pure solidstate apple pomace, three kinds of solidstate andliquidstate apple pomace,which was degraded by three cellulose enzyme,the 10% glucosesolution were used as fermentable culture medium and 17 strains of uncultivated Aspergillusniger were used as primitive strains to carry out the citric acid fermentation experiment by twoways of solidstate and liquidstate fermentation.the results of experiment were processed bySAS(stastistic Analysis system),some of fermentation liquid was analysised by paperchromatography. The results showed that among 17strains of uncultivated Asp.nigerprovided,7 strains, FG15,FG17,FG23,FG26,FG30,FG41,FG45 etc. not only have high abilityto produce cetric acid ,but their natural production capcities in different culture medium werefairly stable,other acid can not be found in fermentation liquids.Those 7 strains of Asp.nigerwere the ideal fungi which can be used to produce citric acid and mutate to ferment applepomance producing citric acid effectively. 3.The results of mutation breeding by ultraviolet and isotope Co-?ray. When 7 strains of 60uncultivatec Asp.niger that were selected from 17 strains were induced by ultraviolet ray and60Co-?ray,the tendency of all 7strains'kill rates rised with the time increaced,but for onespecific mutagen,different strain had different durability... |
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