混料设计在无花果汁乳酸菌发酵剂配比研究中的应用

为了寻求无花果汁乳酸菌发酵剂中各菌种的最佳组合,采用混料设计法研究了乳酸菌的不同组合对无花果发酵液总活菌数和产酸量的影响,建立了发酵剂中各菌种配比与发酵液总活菌数和产酸量的回归模型,考察了发酵剂中各菌种的互作效应,获得了最佳菌种配比为干酪乳杆菌(Y5-2b)、植物乳杆菌(Yj)和嗜酸乳杆菌(NCFM)1∶1∶2,此时,发酵液总活菌数为1.86×109 CFU/m L,产酸量为7.41 g/L。     

商用酱油曲精中微生物分布研究

对总好氧菌、总芽孢菌、乳酸菌、肠道菌群及霉菌在商用酱油曲精及种曲中的分布状态进行了研究。结果表明,不同品牌的曲精中微生物分布状态差异显著,其中霉菌的菌落总数均大于109cfu/g,种曲中霉菌的数量只有107cfu/g。而总好氧菌、肠道菌群、乳酸菌及总芽孢菌菌落数均差异显著,分别为102cfu/g~109cfu/g、103cfu/g~109cfu/g、103cfu/g~108cfu/g、104cfu/g~108cfu/g。曲精及种曲中水分及蛋白酶活也存在显著差异。     

益生菌混合发酵高产工艺优化的研究

对3株乳酸菌株进行混合发酵,采用单因素与正交试验相结合优化发酵的培养基及培养条件以得到高活菌数的发酵液。研究表明,最佳发酵培养基配方为:蔗糖10 g/L,胰蛋白胨10g/L,酵母膏10 g/L,Na_2HPO_4 7 g/L;最佳培养条件为发酵温度37℃,接种量(v/v)0.5%,初始p H8.5,摇床转速200 r/min,发酵周期16 h。此时发酵液中菌体量可比优化前增加42%,活菌数达到1.8×10~(13) cfu/m L,研究结果为工业化生产高活菌数的乳酸菌制剂提供参考。     

EM菌固态发酵生产米糠微生态产品的工艺优化

以米糠为原料,选用EM菌作为固态发酵菌种,以活菌数为指标,通过单因素和L9(34)正交试验确定了EM菌剂多菌种混合发酵米糠的最佳条件.结果表明:发酵温度28℃、接种量10％、培养时间84 h的效果最好.在此条件下发酵后,发酵产物样品中活菌数为3.5×1011cfu/g.在最优混合培养条件下研究了发酵液中的糖化酶、纤维素酶、淀粉酶的酶活性,3种酶的最大酶活力分别为9 985.1、1 998.4和632.4 U/g.     

耐氧性双歧杆菌的驯化及其培养条件的研究

通过对一株青春双歧杆菌的耐氧驯化,获得了具一定耐氧能力的双歧杆菌ad,该菌株可在含有一定空气容积的密闭容器中良好生长。并探讨了以大豆为主要原料发酵培养青春双歧杆菌ad的工艺条件,其最佳培养基配方为:豆浆浓度3BX,葡萄糖1%,自制乳肽0.5%,番茄汁2.5%,胡萝卜汁2.5%;pH7.0;接种量2%;培养温度37℃;厌氧培养24～48h。发酵液活菌数可达6.9×109cfu/mL。青春双歧杆菌ad发酵液原液直接冷冻干燥,无须添加其他保护剂;双歧杆菌ad冻干前增加温度前处理环节,可提高菌体成活率;双歧杆菌ad含水冻干粉活菌数达1.0×1010cfu/g;绝干样品活菌数达1.1×1010cfu/g。     

缓解铅毒性植物乳杆菌活菌片剂的制备方法及稳定性研究

本文研究了缓解铅毒性植物乳杆菌CCFM8661活菌片剂制作过程中保护剂对菌体活性的保护作用以及抗氧化物质的变化规律,探讨活菌片剂的储存稳定性。结果表明,10%海藻糖在菌体冷冻干燥及压片过程中对植物乳杆菌CCFM8661活性有良好的保护作用,冷冻干燥后存活率达41.91%;微量物质活菌片剂和植物提取物活菌片剂菌活数分别为8.30×10~9cfu/g及7.93×10~9 cfu/g,存活率分别为19.61%,18.45%。考察了4℃和20℃活菌片剂真空储存稳定性以及抗氧化保护剂对稳定性的影响,结果发现抗氧化保护剂对菌体活性及抗氧化组分影响不明显,4℃低温储存可减少活菌片剂功能成分的损失。     

产蛋白酶乳酸菌发酵乳清蛋白产支链氨基酸的研究

研究了一株产蛋白酶的德氏乳杆菌乳亚种(Lactobacillus delbrueckii subsp. lactis)815的高密度发酵条件,确定果糖为最佳碳源、牛肉浸粉和大豆蛋白胨为最佳氮源、发酵温度37℃、pH值恒定为5.5、通氮气。在该条件下,菌悬液活菌数为2.63×109cfu/mL,冷冻干燥后菌粉活菌数为2.93×109cfu/mL。以LB815菌株发酵乳清蛋白,并研究支链氨基酸(branched amino acid,BCAA)随发酵时间的变化情况。结果显示,BCAA在发酵5 h后开始积累,并在26 h含量达到最大值312.55 mg/kg,随后缓慢减少。以高产蛋白酶的乳酸菌菌株发酵乳清蛋白制备富含BCAA的乳清蛋白发酵液,可应用于运动型的发酵乳制品中,提高产品附加值。     

三株益生菌发酵特性的测定

为获得最大生物量,利用比浊法做标准曲线测定发酵液中的活菌数,研究了三株益生菌的发酵特性.结果表明,双歧杆菌S1在pH7.0、150r/min、35℃条件下发酵27h活菌为2.15×109 cfu/mL,保加利亚乳杆菌Q6在pH5.5、200r/min 、35℃条件下发酵36h活菌为4.75×109cfu/mL,嗜热链球菌B6在pH7.0、200r/min、40℃条件下发酵30h活菌为1.43×109cfu/mL.     

乳酸菌增菌培养基筛选及干燥保护剂的选择

对促进乳酸菌生长的营养物质及冻干保护剂进行了研究,结果保加利亚杆菌、嗜热链球菌和嗜酸乳杆菌在液体培养基中菌数增到1010～1011cfu/g,经冷冻干燥后活菌数达到1010cfu/g以上.     

多菌种固态发酵对豆粕、棉籽粕和花生粕组成的混合蛋白原料的影响

以枯草芽孢杆菌和保加利亚乳杆菌为试验菌株,对豆粕、棉籽粕和花生粕组成的混合蛋白原料样品进行多菌种发酵处理,检测发酵过程中的活菌数和营养物质的变化。结果表明:发酵结束后混合蛋白原料样品中枯草芽孢杆菌活菌数为3.1×108cfu/g,保加利亚乳杆菌活菌数为4.45×108cfu/g,乳酸含量为1.98%,大分子蛋白几乎完全分解成小分子蛋白,粗蛋白质含量比发酵前提高了7.89%,寡肽含量比发酵前提高了129.36%,抗营养因子(水苏糖和棉籽糖)几乎完全降解,同时产生了一定量的还原糖。     

酸马奶中乳酸菌与酵母菌的共生发酵特性

对内蒙古锡盟地区酸马奶中分离出的1株乳酸菌和1株酵母菌进行混合培养,初步确定双菌混合发酵的最佳培养条件：双菌发酵计数乳酸菌活菌数的最佳发酵温度为30℃摇床培养12h再转到37℃静置培养,最佳发酵时间为20h,脱脂乳中添加的营养成分最优配方为蛋白胨1g/100mL、蔗糖0.5g/100mL、酵母浸粉0.5g/100mL;双菌发酵计数酵母菌活菌数的最佳发酵温度为37℃静置培养8h再转到30℃摇床培养,最佳发酵时间为32h,脱脂乳中添加的营养成分最优配方为蛋白胨0.5g/100mL、蔗糖0.5g/100mL、酵母浸粉0.5g/100mL;选用乳酸菌与酵母菌质量比1:1作为菌种配比。 同时在最佳生长条件下探讨乳酸菌与酵母菌的相互作用关系以及后发酵对二者共生作用的影响,结果表明,促进乳酸菌生长的活性物质生成的时间为12h以前(即将酵母菌在5号配方中30℃摇床培养),促进酵母菌生长的活性物质生成的时间应为16h以前(即将乳酸菌在1号配方中37℃静置培养),在后发酵过程中,乳酸菌与酵母菌双菌培养的活菌数都极显著高于单菌培养(P＜0.01)。     

汾酒大曲中乳酸菌的调查研究

通过选择性培养基对清香型汾酒大曲中的乳酸茵进行计数。结果表明,将汾酒大曲贮存期从3个月增加到6个月,乳酸茵非但没有减少,反而略为增加;当贮存到6个月时,红心曲中乳酸菌数量最多,达到7．10x10^9cfu／g,其次是清茬曲5．33x10^9cfu／g,最后是后火曲2．42x10^9cfu／g。通过发酵类型实验发现,仅有菌株QR6产气为异型发酵乳酸茵,进一步通过提取分析16SrDNA将其鉴定为融合魏氏菌。     

芡实发酵奶发酵工艺优化研究

基于保加利亚乳杆菌和乳酸链球菌制作芡实发酵奶工艺,在单因素实验基础上选取接种量、发酵时间、发酵温度、柠檬酸添加量为自变量,利用响应面分析法研究各自变量及交互作用对芡实发酵奶中乳酸菌浓度的影响,模拟得到二次多项式回归方程的预测模型。实验结果表明,接种量为3.3%,发酵时间为7.4h,发酵温度为40.5℃,柠檬酸添加量为0.16%时乳酸菌浓度最高,在此条件下乳酸菌浓度平均值为1.923×109cfu/mL,与理论预测值1.920×109cfu/mL相比相对误差为1.56%,说明通过响应面优化得出的回归方程有一定的实践指导意义。      

高产苯乳酸菌株的筛选及其在豆粕发酵中的应用

以实验室保存的性能优良的乳酸菌为研究对象,采用薄层层析（TLC）法和高效液相色谱（HPLC）法筛选出高产苯乳酸的菌株,并利用该菌株对豆粕进行固体发酵,研究其对发酵豆粕的微生物、pH值、水分含量、粗蛋白、酸溶蛋白、总酸和苯乳酸含量的影响。结果表明,筛选得到3株产苯乳酸的菌株,其中植物乳杆菌（Lactobacillus plantarum）BLCC2-0069为高产苯乳酸的菌株,其以3 g/L苯丙酮酸为底物发酵48 h时发酵液中苯乳酸含量最高为4.39 g/L。利用该菌株固态发酵豆粕3 d时,乳酸菌活菌数＞109 CFU/g,霉菌活菌数≤10 CFU/g,大肠杆菌未检出;pH值降至4.5左右,水分、粗蛋白、酸溶蛋白、总酸和苯乳酸含量分别为36.78%、46.65%、10.51%、26.37 g/kg和424.02 mg/kg,发酵效果显著优于对照组（P＜0.05）。     

Inoculant effects on alfalfa silage: fermentation products and nutritive value

The effect of 14 microbial inoculants on the fermentation and nutritive value of alfalfa silages was studied under laboratory conditions. The first cut (477 g of dry matter/kg) and second cut (393 g of dry matter/kg) of a second-year alfalfa stand were ensiled in 2 trials. In both trials alfalfa was harvested with standard field equipment. All inoculants were applied at 1.0 × 10⁶ cfu/g of crop. Uninoculated silages served as controls. After inoculants were added, the chopped forages were ensiled in 1.0- and 0.5-L anaerobic glass jars, respectively, at a density of 500 g/L. Each trial had 15 treatments (uninoculated control and 14 inoculants), with 4 silos per treatment. Silos were stored for a minimum of 30 d at room temperature (∼22°C). In first-cut silage, all inoculants but one reduced pH relative to the uninoculated control, and all but 2 of the homofermentative strains shifted fermentation toward lactic acid. In second-cut silage, the epiphytic lactic acid bacterial population was 2.7 × 10⁷ cfu/g, and only commercial inoculants produced significant shifts in fermentation. Overall, microbial inoculants generally had a positive effect on alfalfa silage characteristics in terms of lower pH and shifting fermentation toward lactic acid with homofermentative lactic acid bacteria or toward acetic acid with heterofermentative lactic acid bacteria, Lactobacillus buchneri. These effects were stronger in the commercial products tested. In spite of the positive effects on silage fermentation, 48-h in vitro true DM digestibility was not improved by inoculation with lactic acid bacteria.     

肉制品发酵剂菌种筛选及发酵工艺条件优化

为获得优良的肉制品发酵剂,将酸马奶酒中分离所得4株乳酸菌进行培养。以标准的植物乳杆菌为对照,通过生化特性分析、耐盐性、耐亚硝酸盐性、产酸能力等试验对其进行优势菌种筛选,最终筛选出一株发酵性能较好的乳酸菌Lactobacillus5(BL5)。以接菌量、BL5和标准肉葡萄球菌Staphylococcus(Stl)配比、葡萄糖添加量作为影响发酵的三个因素,测定pH达到5.3左右的发酵时间和色泽。结果表明:当接菌量1×106cfu/g,BL5︰Stl=2︰1,葡萄糖添加量2%时,发酵时间较短为8 h,pH为5.2±0.1,L*,a*值都较大,发酵肉的色泽较好。故将其作为该发酵剂的最佳发酵条件。     

Characterisation of the microflora of attiéké, a fermented cassava product, during traditional small-scale preparation

Attiéké is a fermented cassava product consumed mainly in Cote d'Ivoire. The aim of this study was to characterise the attiéké fermentation by examining products from 15 small-scale production sites at various stages of its preparation. For the preparation of attiéké, fresh cassava is grated to a pulp and inoculated with 10% of a spontaneous traditional inoculum. The inocula contained aerobic mesophiles at mean numbers of 8.2 x 10(7) cfu/g and lactic and acetic acids at mean concentrations of 0.2% and 0.1%, respectively. The mean pH was 5.0. Lactic acid bacteria were the dominant microorganisms in cassava pulp throughout fermentation with the mean numbers being 1.2 x 10(9) cfu/g after 15 h. The identification to the species level of microorganisms from one representative attiéké production of good quality showed that, at the start of fermentation, Leuconostoc mesenteroides subsp. mesenteroides was present in the highest numbers, accounting for 20% of all lactic acid bacteria. As the fermentation proceeded, this species was replaced by homofermentative lactic acid bacteria, Lactobacillus salivarius and Lactobacillus delbrueckii subsp. delbrueckii, present at 20% and 16%, respectively, and obligate heterofermentatives, Lactobacillus fermentum and Lactobacillus confusus at 12% and 10%, respectively, of total lactic acid bacteria in the flora at the end of fermentation. High numbers of acid-sensitive microorganisms, Bacillus circulans, Bacillus lentus, Enterobacter sakazakii, Enterobacter cloacae and Klebsiella pneumoniae subsp. pneumoniae, were transferred to the pulp in the inocula, but acidification to a mean pH of 4.4 with mean lactic and acetic acid concentrations of 0.59% and 0.2%, respectively, prevented their growth and reduced their numbers to less than 10(2) cfu/g at the end of fermentation. The mean numbers of Candida tropicalis, the main yeast present, remained relatively constant at about 10(5) cfu/g throughout attiéké production. The mean numbers of aerobic mesophiles decreased to below 10(2) cfu/g as a result of the steaming process. The finished attiéké had a mean pH of 4.4 and mean lactic and acetic acid concentrations of 0.6% and 0.1%, respectively.     

植物乳杆菌发酵梨原汁饮料的研究

乳酸菌发酵果蔬汁,因其绿色、健康、营养,成为日常生活中必不可少的食物。我国梨种植业广泛、产量高,并且梨果自身营养素全面。因此,该研究利用3种复合益生菌研制一款发酵梨浆饮料。对发酵优势菌株进行发酵剂制备并优化工艺,保护剂配比为:谷氨酸钠2%、海藻糖5%、乳糖5%、脱脂乳10%、保护剂添加量与菌泥为3∶1(mL/g),在这些条件下,得到菌粉发酵剂菌活为8.48×10^9cfu/g;在发酵梨浆应用的工艺进行优化,最佳工艺为:植物乳杆菌299、保加利亚乳杆菌717、嗜热链球菌176体积比为4∶1∶1、接种量为8%、发酵温度为37℃、发酵时间72 h。此条件下梨浆得到充分发酵,口感突出,风味酸甜;测定梨浆发酵前后有机酸的变化:酵前梨浆中含量较为丰富的有机酸为:柠檬酸、苹果酸、乳酸、草酸。其中苹果酸、柠檬酸有优势有机酸,含量分别为:36.49、38.59 mg/100 g。经3种复合乳酸菌发酵后,梨浆中有机酸含量发生变化,有机酸含量依次为:乳酸、柠檬酸、苹果酸、草酸。其中乳酸含量由1.65 mg/100 g升高为116.27 mg/100 g。     

嗜酸乳杆菌冻干影响因子的研究

传统的乳酸菌发酵剂因活化过程复杂,极易引起污染而影响发酵乳的质量。目前,多采用冷冻干燥技术制备直投式粉末状乳酸发酵剂。然而,菌种冻干时机的把握和冻干保护剂的选择,将直接影响乳酸菌在冷冻干燥前后的存活率以及存活期。本文研究了嗜酸乳杆菌的生长曲线,选用蔗糖、乳糖、甘油、VC、谷氨酸钠、麦芽糊精、脱脂乳粉等为嗜酸乳杆菌冻干保护剂进行了冻干研究。结果表明:①嗜酸乳杆菌发酵液培养至酸度为100°T、pH值4.8时,OD410nm=0.511为最大,是最佳发酵终止时间;②嗜酸乳杆菌冻干保护剂配方以5%麦芽糊精、2%VC、5%甘油为最佳冻干保护剂组合,此时嗜酸乳杆菌冻干菌粉活菌数为2.34×109cfu/g。     

Molecular typing techniques to characterize the development of a lactic acid bacteria community on vacuum-packaged beef

The development of a community of lactic acid bacteria from vacuum-packaged beef was investigated during a 6-week storage trial at 2 degrees C. The lactic acid bacteria population was monitored by using molecular techniques to identify a random sample of isolates at biweekly intervals during the storage trial. The polymerase chain reaction and a randomly amplified polymorphic DNA technique were used to identify and distinguish populations of lactic acid bacteria that developed during the storage trial. At week 0, the population of lactic acid bacteria was 3.5 log cfu/120 cm2 and by week 6, the population reached a maximum of 7.6 log cfu/120 cm2. A sampling from the week 0 population indicated a mixed community of Lactobacillus curvatus, Lactobacillus sakei and Leuconostoc spp. However, the sampling from week 6 indicated the population composition had changed to one where a single Leuconostoc strain predominated. This strain demonstrated antagonism towards the growth of other lactic acid bacteria isolated during the study. Additionally, the strain inhibited the growth of foodborne pathogens Escherichia coli O157:H7 and Listeria monocytogenes. DNA sequence data from the 16S rRNA gene suggested that the isolate may be a Leuconostoc gelidum strain.