| Enzymatic modifications of soybean protein isolated (SPt) were studiedsystematically, and SDS-PAGE gelatin electrophoresis method was adopted toanalyse the products of hydrolysis.Comparision of foaming ability and emulsifyingcapacity before and after enzymatic modification was done.Finally, the product ofhydrolysis was applied to microorganism culture medium to examine the effect ofdydrolysis product with different hydrolysis degree on microbial gowth.This dissertation mainly includes four aspects:1 Enzymatic modification of soybean protein isolatedEnzymatic modification of soybean protein isolated by single and doubleproteinase(neutral proteinase produced by AS 1.398 and alkaline proteinase producedby 2709 was adopted) were studied using degree of hydrolysis of soybean proteinisolated as appraisal index.Some conclusions were made after modification ofsoybean protein isolated by neutral proteinase that the optimal pretreatment conditionswere 80℃, 15min.After some single factor experiments,several results were foundthat those conditions that were beneficial for hydrolys were 4％substrateconcentration,4 000U/gSPI under 50℃for 4.5h.Orthgonal design was used foroptimation of enzymatic conditions and analysis of variance(ANOVA) was adopted toapprise the influences of subsrate concentraions,temperature,added enzyme amountand dealt time on hydrolysis,results showed that added enzyme amouts andtemperature is remarkable for hydrolysis(P＜0.01),hydrolysis time is notable forhydrolysis (P＜0.05),and then, substrate concentrations is not notable for enzymaticmodification (P＞0.05).Results of ezymatical modification of SPI by alkalineproteinase indicated that the optimal pretreatment conditions were 70℃,10min.Singlefactor experiments showed that the optical modification conditions were 3％substrateconcentration,4 000U/gSPI under 50℃for 4.5h.In order to comprehensiveconsideration of influence of substrate concentrations, temperature and enzymeticaltreatment time on degree of soybean protein isolated, Orthogonal design and analysisof avariance(ANOVA) were adopted,results indicated that those effects of addedenzyme amount and temperature were notable(P＜0.05),but the influences of dealttime by alkaline and temperature were not notable(P＞0.05).For the sake ofconsideration of double enzyme on hydrolysis,single enzyme modification experimentwere carried out using pH,temperature,dealt time and ratio of double as affectingfactor,results indicated that under those conditions of the ratio of AS1398 to 2709 is1:3,pH9.5,60℃,dydrolysis for 3.oh,hydrolysis degree would be better. In the interestof considation of interaction effect of four factors,orthogonal design was applied and results showed that the influences of ratio of double enzyme(neutral proteaseandalkaline protease) is notable for degree of SPI followed by enzymeticaltemperature and pH value,but the effect of enzymetical treatment time is notremarkable.2 Analysis of enzymatical modification product of SPI by SDS-PAGE gelatinelectorphoresisRegression equation of standard curve of low molecular weight mark isy=-0.9446x+4.9637, and pertinency is 0.9986.SDS-PAGE was used for analysis ofhydrolysis of SPI by neutral proteinase, results showed that chromatogram beltsincrease with the raise of hydrolysis degree and molecular weight of most hydrolysiswas 14.4～60KD.Those belts of hydrolysis of SPI by alkaline proteinase were morethan hydrolysis product produced by neutral proteinase, and molecular weight of mosthydrolysis was 14.4～31KD.SDS-PAGE analysis of hydrolysis of SPI by doubleenzyme showed that chromatogram belts increase as the increase of hydrolysisdegree.Two particular chromatogram belts of 31.8KD and 27.8KD can be found whenhydrolysis for 6h by neutral proteinase and alkaline proteinase.In order to understandthe process of hydrolysis,the analysis of hydrolysis product produced by neutralprotease,alkaline proteinase and double enzyme were carried out on one SDS-PAGEgelatin,results showed that chromatogram belts of double enzyme is more than singleenzyme.and chromatogram belts of hydrolysis produced by 2709 is more thanhydrolysis produced by AS 1.398.3 Studies on emulsifying capacity and foaming ability of hydrolysis of SPIEmulsifying capacity and foaming ability of hydrolysis of SPI were studied.Fromthe relationship of hydrolysis and foaming capaticy, several conclusions can be madethat foaming capacity is best for hydrolysis product produced by doubleenzyme,followed by hydrolysis product generated by 2709,AS1398,especially forSPI,the foaming ability is the worst. From the relationship of hydrolysis andemulsifying capacity, a phenomenon can be found that SPI has the best emulsifyingcapacity, followed by hydrolysis product produced by AS 1398 and 2709.and foamingcapacity of hydrolytic product produced by double enzyme is the worst.Inconclusion,with the increase of hydrolytic degree of SPI,foaming capacityincrease,but emulsyfing ability decrease.4 Peptone and its applications in microorganism culture mediaDryness treatment of hydrolysis of SPI was performed by infrared dryness,galvanothermy dryness and freeze dryness and surfacial characteristics and solubilitywas studied, results showed that structure of peptone desiccated by freeze dryness wassoft and good-soluble.For peptone produced by infrared dryness, galvanothermydryness,its surfacial structure is compact and difficult to dissolved.Hydrolysis productproduced by single enzyme and double enzyme were adopted to culturemicroorganism,several conclutions were made that for the growth of Bacillus subtilis 1398,peptone by double enzyme hydrolysis is excel to peptone brought.ForAcetobacter, peptone produced by myself is better than peptone brought when culturefor 2～8h,but the effect is not notable after culturing for 8h.For lactobacillus, peptoneproduced by myself is excel to peptone brought when culture 2～6h,but peptonebrought is better than peptone produced by meself.but for Bacillus subtilis NTG14,peptone produced by meself is beneficial for growth.Microbial growth experiment was processed with hydrolysis product of differenthydrolytic degree using microbial strain biomass as appraisal index,results showedthat for Bacillus subtilis 1398,15％of hydrolysis degree is beneficial for its growthwhen culture 4h,but 20％of hydrolysis degree is better when culture for 6h andlater.For growth of lactobacillus and Bacillus subtilis NTG14,15％of hydrolysis degreeis the best.15％of hydrolysis degree and 20％hydrolysis degree is better whenculture for 4～8h and 10～12h respectively.
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