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《食品与发酵工业》2019,(19):45-51
为了提高牛类芽孢杆菌BD3526发酵乳中α-葡萄糖苷酶抑制剂的产量,采用单因素实验和响应面法对发酵参数进行优化。BD3526合成α-葡萄糖苷酶抑制剂的优选参数为:培养时间43 h、培养温度29℃、脱脂乳质量浓度为5 g/100 g(水)、三角瓶装量为50 mL/250 mL。在此条件下,BD3526发酵乳对α-葡萄糖苷酶的半数抑制浓度IC50为15. 1 mg/mL,与理论值(14. 6 mg/mL)基本一致,比优化前(22. 4 mg/mL)降低了33%。该研究为α-葡萄糖苷酶抑制剂的后续分离工作提供了保障,也为其他类似的研究提供了理论依据。 相似文献
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通过比色法测定酶活,比较5株植物乳杆菌(Lactobacillus plantarum)产β-葡萄糖苷酶的特性,对胞内β-葡萄糖苷酶最佳反应pH和温度进行了研究,考察了氯化钠及乙醇对β-葡萄糖苷酶活性的影响。结果表明,5株植物乳杆菌都可以产生胞内β-葡萄糖苷酶,其中比酶活最高的为菌株W-4(14.168 U/g),其次是菌株Y-12(13.015 U/g),之后分别是菌株Y-20(11.359 U/g)、菌株1.3919(7.029 U/g)及菌株Y-22(4.630 U/g);植物乳杆菌W-4和1.3919还可以产生胞外酶;菌株W-4的胞内β-葡萄糖苷酶的最适反应pH为4.0~4.5,菌株Y-12的最适pH为4.5,菌株Y-20和1.3919的最适pH为5.5,菌株Y-22的最适pH为5.0;菌株W-4、Y-20、Y-22及1.3919的最适反应温度均为30 ℃,而菌株Y-12的最适反应温度为37 ℃。不同含量的氯化钠和乙醇对5株植物乳杆菌的β-葡萄糖苷酶活性具有一定的抑制作用,且浓度与抑制作用呈正相关。 相似文献
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从鸡血藤中获得醇提物(alcohol extract, ESs)及水提物(water extracts, WSs),研究其对α-淀粉酶和α-葡萄糖苷酶的抑制作用。结果表明,ESs的抑制效果显著高于WSs。为深入研究鸡血藤对2种酶的抑制作用,采用不同极性溶剂对ESs进一步萃取,获得W-ESs、D-ESs、N-ESs、E-ESs四个组分。实验结果表明,在同一浓度范围,ESs及4个组分的抑制效果存在差异。对α-淀粉酶的抑制效果为:W-ESs>D-ESs>ESs>N-ESs>E-ESs;对α-葡萄糖苷酶的抑制效果为:W-ESs>ESs>N-ESs>E-ESs>D-ESs。其中W-ESs对2种酶的抑制作用最好,IC50值分别为(0.88±0.02) mg/mL和(15.82±2.79)μg/mL。绘制Lineweaver-Burk曲线确定酶抑制类型,结果显示,WSs、ESs、W-ESs及N-ESs对α-淀粉酶为反竞争性抑制,D-ESs和E-ESs为竞争性和非竞争性混合抑制。对于α-葡萄糖苷酶,W-ESs、D-ESs和E-ESs... 相似文献
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目的:进一步研究干、鲜马齿苋的降血糖活性及降糖机制。方法:分别将干燥和新鲜马齿苋用乙醇为溶剂浸泡提取,制备干燥马齿苋乙醇提取物(Dried Portulaca oleracea L. ethanol extracts,DEP)和新鲜马齿苋乙醇提取物(Fresh Portulaca oleraceaL. ethanol extracts, FEP)。再分别将DEP和FEP用水混悬,依次用正己烷、乙酸乙酯、正丁醇进行萃取,从DEP得到H-DEP、E-DEP、D-DEP和W-DEP,从FEP得到H-FEP、E-FEP、D-FEP和W-FEP。分别对DEP和FEP以及所得各种萃取物进行酶抑制活性测试,结果:E-FEP对2种酶的抑制作用最好,IC50值分别为(0.094±0.001)mg/m L和(33.63±0.42)μg/m L。绘制Lineweaver-Burk曲线确定酶抑制类型:对于α-淀粉酶,H-DEP、E-DEP、H-FEP及E-FEP为非竞争性抑制,DEP、FEP、D-DEP、W-DEP、D-FEP及W-FEP为竞争性和非竞争性混合抑制;对于α-葡萄糖苷酶,H... 相似文献
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L-阿拉伯糖对α-葡萄糖苷酶抑制活性的体外试验研究 总被引:1,自引:0,他引:1
目的探讨L-阿拉伯糖对小肠α-葡萄糖苷酶的抑制作用及与阿卡波糖的联用效应。方法利用体外实验,提取大鼠小肠粘膜上清液为α-葡萄糖苷酶粗酶液,分别以终浓度为60 mg/ml蔗糖、20 mg/ml麦芽糖/α-糊精为底物,建立最佳抑制反应体系,测定L-阿拉伯糖对α-葡萄糖苷酶抑制活性(IC50)及抑制作用类型;采用4×3析因设计,研究L-阿拉伯糖与阿卡波糖联用效果。结果以蔗糖、麦芽糖、α-糊精为底物时,L-阿拉伯糖对小肠α-葡萄糖苷酶活性均有一定抑制作用,但选择性较高地抑制蔗糖酶活性,当L-阿拉伯糖添加量为0.5%蔗糖浓度时酶活性抑制百分率>50%,最高酶活性抑制百分率约93%,且有良好剂量-反应关系,IC50为0.164 mg/ml,抑制类型为反竞争性抑制(Ki,0.558 mg/ml);与阿卡波糖联用二者有交互作用,尤其以蔗糖为底物时联用效果较明显,联合应用可能提高了抑制活性。结论 L-阿拉伯糖有抑制α-葡萄糖苷酶活性作用,尤其对蔗糖酶有良好的选择性抑制;在α-葡萄糖苷酶抑制作用方面,其与阿卡波糖有一定联用效果,L-阿拉伯糖在含糖食品中可能有较良好的实际应用前景。 相似文献
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干酪乳杆菌KW3产胞外多糖的研究 总被引:1,自引:0,他引:1
从西藏农家开菲尔粒中筛选出1株高产胞外多糖(EPS)的乳酸菌KW3,生理生化试验和16S rDNA测序结果经鉴定其为干酪乳杆菌,在乳清培养基中的胞外多糖产量达到178mg/L。体外抗氧化试验表明:KW3胞外多糖总还原力达到(138.28±5.35)mgVC/g;当其质量浓度达到200μg/mL时,对DPPH自由基的清除率37.53%,FRAP值为(600.16±15.23)FeSO4.7H2Oμmol/L。体内抗氧化试验显示KW3胞外多糖可显著降低衰老小鼠血清、肝和脑组织中的MDA含量,提高其SOD活性和GSH-Px活性。 相似文献
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为研究干酪乳杆菌体外利用低聚果糖的生长代谢过程,分别以0.5%、1.5%、3%低聚果糖替代0.5%葡萄糖作为培养基碳源,取0、4、8、12、18、24h发酵液测p H、菌落数、代谢产物。结果表明:随着培养时间的延长,培养基中p H降低;0.5%低聚果糖培养基中干酪乳杆菌数量在8h时达到最高值,增加低聚果糖浓度到1.5%,干酪乳杆菌的数量随之增加;继续增加低聚果糖浓度到3%,干酪乳杆菌数量没有明显差异(p>0.05)。干酪乳杆菌代谢低聚果糖在4h时乙酸产量达到最高值,且3%低聚果糖培养基中乙酸产量是0.5%、1.5%低聚果糖的2倍;乳酸产量随着培养时间的延长逐渐积累,3%低聚果糖培养基中乳酸产量最多,干酪乳杆菌利用低聚果糖的主要代谢产物为乙酸和乳酸。 相似文献
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Marzieh Hosseini Nezhad Malik Altaf Hussain Margaret Lorraine Britz 《Critical reviews in food science and nutrition》2015,55(6):740-749
Survival in harsh environments is critical to both the industrial performance of lactic acid bacteria (LAB) and their competitiveness in complex microbial ecologies. Among the LAB, members of the Lactobacillus casei group have industrial applications as acid-producing starter cultures for milk fermentations and as specialty cultures for the intensification and acceleration of flavor development in certain bacterial-ripened cheese varieties. They are amongst the most common organisms in the gastrointestinal (GI) tract of humans and other animals, and have the potential to function as probiotics. Whether used in industrial or probiotic applications, environmental stresses will affect the physiological status and properties of cells, including altering their functionality and biochemistry. Understanding the mechanisms of how LAB cope with different environments is of great biotechnological importance, from both a fundamental and applied perspective: hence, interaction between these strains and their environment has gained increased interest in recent years. This paper presents an overview of the important features of stress responses in Lb. casei, and related proteomic or gene expression patterns that may improve their use as starter cultures and probiotics. 相似文献
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JICHENG WANG ZHUANG GUO QING ZHANG LIYA YAN YONGFU CHEN XIA CHEN XIAO-MING LIU WEI CHEN HE-PING ZHANG 《International Journal of Dairy Technology》2010,63(1):105-112
The effect of four inoculation levels of Lactobacillus casei Zhang (0.001, 0.01, 0.1 and 1.0 g/100 g) on the fermentation characteristics of set-style yogurt, and the changes in viable counts of lactic acid bacteria, pH value, syneresis, apparent viscosity, sugar and organic acid contents were determined during fermentation and storage over 21 days. The presence of 0.001 to 0.01 g/100 g L. casei Zhang did not affect the growth of the yogurt strains, and the yogurt inoculated with 0.00 1 g/100 g of L. casei Zhang had the highest apparent viscosity among the samples. However, a high inoculated level of L. casei Zhang (1.0 g/100 g) resulted in yogurts with inferior quality. 相似文献
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用胆固醇氧化酶指示平板和测定胆固醇氧化酶活力的方法对干酪乳杆菌21008是否具有产生胆固醇氧化酶的能力进行了研究,并以添加胆固醇的MRS培养基和蛋黄对菌株降胆固醇能力进行了评价。结果发现干酪乳杆菌能产生胆固醇氧化酶类似物,并且测得胞内酶活为302.7U/L,但没有胞外酶。菌株使MRS-CHO培养基中的胆固醇降低69.5%,主要是通过菌体细胞吸收、转化作用;而在蛋黄中发酵,优化条件下:V蛋黄∶V水=2∶1,接种量8%,发酵30h,胆固醇降低16.82%,pH降为5.57。 相似文献
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Beáta Koréneková Jana Kottferová Marián Korének 《European Food Research and Technology》2000,211(2):136-140
The aim of this work was to observe the effects of nitrites and nitrates on the titratable acidity of milk after addition
of Lactobacillus helveticus (TX 121) and L. casei (CAD 154) dairy cultures and on the levels of nitrate and nitrite. After adding L. helveticus and nitrites the increasing concentrations of the latter brought about a marked decrease in titratable acidity. In milk containing
100 mg·kg–1 nitrite the resulting concentration was 39.33 mg·kg–1 NaNO2. Nitrates caused a less obvious decrease in titratable acidity, giving 13.27 g·l–1 lactic acid. In milk containing 100 mg·kg–1 NaNO3 the resulting concentration was 24.99 mg·kg–1 NaNO3. Experiments with L. casei and a nitrite additive revealed a decrease in titratable acidity to 8.89 g·l–1 lactic acid. After incubation, nitrite levels were reduced from 100 mg·kg–1 NaNO2 to 37.81 mg·kg–1 NaNO2. Nitrates were also stated to inhibit the titratable acidity of the sample, which decreased to 11.42 g·l–1 lactic acid. Nitrates were reduced to 46.99 mg·kg–1 NaNO3. The present study shows that nitrites, more than nitrates decrease the titratable acidity of milk after addition of L. helveticus and L. casei dairy cultures. A reduction of nitrates and nitrites in milk samples by Lactobacillus was also found. The results of this study can be used in the dairy industry in the production of several types of hard cheese
as well as fermented milk products that use L. helveticus and L. casei dairy cultures.
Received: 31 March 1999 / Revised version: 6 September 1999 相似文献