最大可能数法计数乳品中双歧杆菌数量的研究

目的:建立乳品中双歧杆菌数量快速测定方法。方法:采用莫匹罗星-TPY选择性液体培养基,基于果糖-6-磷酸酮酶酶活测定及最大可能数法确定样品中双歧杆菌数量。结果:该方法所计双歧杆菌数量与平板计数数量在同一数量级。结论:该方法可用于乳品中双歧杆菌的准确计数。     

发酵乳中乳酸菌的选择性计数及分离鉴定

发酵乳产品的菌种组成与活菌数的含量是产品质量的关键。该文通过选择性培养基、基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption/ionization time of flight mass spectrometry, MALDI-TOF-MS)快速鉴定技术及多相鉴定技术探究3种发酵乳中乳酸菌的活菌数及种类。研究结果表明,3种发酵乳产品中,GB 4789.35对乳酸菌总数的计数结果均高于选择性培养基,M17培养基对嗜热链球菌的计数结果均高MC培养基。MALDI-TOF MS快速鉴定表明M17、MRS(含50μg/mL的万古霉素)、双歧杆菌培养基可以选择性的分离发酵乳中的嗜热链球菌(Streptococcus thermophilus)、干酪乳酪杆菌(Lacticaseibacillus casei)和双歧杆菌(Bifidobacterium spp.),酸化MRS培养基对德氏乳杆菌(Lactobacillus delbrueckii)的选择性较差,不能在含有双歧杆菌的发酵乳中选择性分离德氏乳杆菌。进一步通过多相鉴定确定3种发酵乳产品中乳酸菌在...     

乳酸菌菌粉定量计数方法研究

目的:以9株乳杆菌、6株双歧杆菌、3株球菌、1株凝结芽孢杆菌菌粉为研究对象,在国标GB 4789.35-2016的基础上,对稀释倍数、稀释液成分、培养基成分进行比较研究,考察对乳酸菌菌粉计数活菌数的影响。方法:采用稀释平板计数的方法,对不同的乳酸菌菌粉进行活菌计数。结果:初始乳酸菌菌粉样品稀释倍数对最终计数活菌数无明显影响,ISO稀释液对部分乳杆菌、双歧杆菌菌粉的活菌计数结果有显著提高(P<0.05);双歧杆菌菌粉采用TOS琼脂培养基的计数结果显著优于国标培养基(P<0.05);凝结芽孢杆菌菌粉采用改良芽孢计数培养基计数结果优于PCA和NA计数培养基。结论:平板计数方法中,稀释液中含有酪蛋白胨能提升双歧杆菌菌粉的活菌计数数量;TOS琼脂培养基更有利于双歧杆菌的增殖培养;改良芽孢计数培养基更有利于凝结芽孢杆菌的芽孢萌发增殖。     

嗜酸乳杆菌、双歧杆菌和干酪乳杆菌的选择性计数

介绍了干酪乳杆菌、嗜酸乳杆菌和双歧杆菌的选择性计数方法。LC培养基只能计数干酪乳杆菌,MRS-水杨素（或山梨醇）培养基可以计数嗜酸乳杆菌和干酪乳杆菌;而MRS培养基可以计数这3种益生菌,通过减法原则从嗜酸乳杆菌、干酪乳杆菌和双歧杆菌混合物中单独计数。另外,MRS-NNLP培养基也可用于选择性计数双歧杆菌。     

实时荧光定量PCR法测定发酵乳中双歧杆菌

对实时荧光定量聚合酶链式反应(PCR)技术检测发酵乳中双歧杆菌的DNA提取方法、PCR扩增效率、标准曲线绘制进行探讨,通过比较分析碱式提取法、玻璃珠破碎法和酶解法3种提取方法对发酵乳中总DNA提取效率、4种不同参考菌株的PCR扩增效率以及单一菌株标准曲线与混合菌株标准曲线的计数结果,建立实时荧光定量PCR快速测定发酵乳制品中双歧杆菌数量方法。结果表明：酶解法提取发酵乳中总DNA效果最好,OD260/280比值基本接近1.80,且提取的质量浓度含量最高;不同菌株的PCR扩增效率不同,其中参考菌株1.2213的Ct值与其他3菌株的Ct值存在显著性差异;根据单一菌株绘制标准曲线与混合菌株绘制标准曲线计数结果无显著性差异,后者计数结果更客观、准确。采用酶解法获取样品中的菌体细胞,基于混合菌液绘制标准曲线,采用实时荧光定量PCR技术确定发酵乳中双歧杆菌种属数量,可快速、准确地测定发酵乳中双歧杆菌的数量。     

益生菌产品中双歧杆菌计数培养基的比较研究

对添加单株双歧杆菌(分别为乳双歧杆菌BB12和长双歧杆菌BB536)的益生菌产品进行双歧杆菌计数实验.比较了在相同的稀释条件和培养条件下,倾注MRS、半胱氨酸盐酸盐+MRS(CYS-MRS)、BBL3种培养基,培养计数结果的差异.结果对添加乳双歧杆菌BB12的益生菌产品,3种培养基计数结果差异较显著(P＜0.05),B...     

双歧杆菌在发酵乳中活性的研究

分别使用两歧双歧杆菌和长双岐杆菌制作酸乳并冷藏21d,应用AMC,RMS培养基检测样品的双歧杆菌活菌数。发酵乳中的双歧杆菌的浓度达到10^8-10^9CFU/mL,在21d的冷藏中二种双歧杆菌的活菌数都超过了最小保健剂量10^6CFU/mL。RMS培养基同样有效地分离两歧双歧双歧杆菌和长双歧杆菌,可以采用涂布法和倾注法进行操作,RMS是对酸乳中双歧杆菌计数的最适宜的选择性培养基,使用AMC培养基由于涂布法造成较低的活菌计数。     

发酵乳活性双歧杆菌种类快速识别及定量研究

本文建立了发酵乳制品中双歧杆菌种类和数量快速测定方法。以发酵乳中双歧杆菌为靶标,采用PCR-DGGE技术快速识别双歧杆菌种类;采用Real-Tine PCR手段测定双歧杆菌数量。研究结果表明,PCR-DGGE能准确、快速鉴别双歧杆菌种类,检出限为105 CFU/g;Real-Tine PCR能准确、快速定量双歧杆菌,检出限为104 CFU/g。该方法可用于发酵乳中双歧杆菌的快速识别和定量。     

乳制品中选择性分离与计数植物乳杆菌的方法

根据乳酸菌对抗生素的敏感性、产酸能力和碳源利用不同,研制出植物乳杆菌分离计数培养基(LPMRS培养基),通过对9种不同的乳酸菌菌株单独试验及混合试验,对该培养基的特异性进行了评价。通过对LP-MRS培养基和MRS培养基中植物乳杆菌计数比较,对该培养基是否抑制植物乳杆菌生长进行了验证。结果表明,该培养基可抑制乳酸乳球菌乳酸亚种、嗜热链球菌、瑞氏乳杆菌、嗜酸链球菌、婴儿双歧杆菌的生长,并能将植物乳杆菌从干酪乳杆菌群分离开来,且对植物乳杆菌无抑制作用。该方法操作简便,成本低,可广泛应用于乳制品中植物乳杆菌的分离和计数。     

茯苓固态发酵产物对益生菌增殖效果初探

通过测定菌体培养液吸光值的方法,进行茯苓发酵产物提取液(FPE)对乳杆菌和双歧杆菌的增殖效果体外实验。结果表明:与异麦芽低聚糖(IMO)和低聚果糖(FOS)相比,添加了FPE的培养基可以更好的促进双歧杆菌的生长(P 0.01),说明FPE可以作为一种双歧因子,促进双歧杆菌的增殖。培养基中FPE的浓度为2.5%～5%时对双歧杆菌和乳杆菌的增殖效果最好。在添加了FPE的培养基中生长的双歧杆菌的生长迟缓期较在未添加的基础培养基中更短,添加FPE的培养液的吸光值明显大于未添加培养液(P0.01),说明发酵产物提取液可以作为一种有效的益生元促进二者生长。     

发酵乳中双岐杆菌种类快速识别

建立发酵乳制品中双歧杆菌快速识别方法。采用酶解前处理法获取样品中菌体细胞,基于PCR-DGGE技术确定发酵乳中双歧杆菌种属。该方法能准确、快速鉴别双歧杆菌,检出限为105cfu/mL。该方法可用于发酵乳中双歧杆菌的准确识别。     

胡萝卜汁双歧杆菌发酵饮料的研制

在添加 5 %脱脂牛乳和 4%～ 5 %蔗糖的胡萝卜汁中接种 5× 1 0 6 /mL的长双歧杆菌 (Bifi dobacteriumlongum) ,发酵 1 0～ 1 4h后或终点pH达到 4 2左右时 ,可获得总菌数在 1 0 9/mL数量级、色泽鲜艳、口感良好、风味上佳的双歧杆菌胡萝卜汁发酵饮料制品。产品低温贮运的保质期为1周左右。     

胡萝卜汁双歧杆菌酸奶的研制

采用已耐氧驯化的两歧双歧杆菌,与普通乳酸菌共同发酵含胡萝卜汁的牛奶制品。试验选定了胡萝卜汁的最佳添加量,并确定生产工艺为：双歧杆菌与乳酸菌以5：3比例添加到含25％胡萝卜汁的牛乳中,于39℃发酵4．5h。制品中双歧杆菌活菌含量达107个／ml以上,风味与普通酸奶类似,营养保健价值远高于普通酸奶。     

Effects of milk products fermented by Bifidobacterium longum on blood lipids in rats and healthy adult male volunteers

The effects of milk products fermented by Bifidobacterium longum strain BL1, a probiotic strain, on blood lipids in rats and humans were studied. Rats were fed a cholesterol-enriched experimental diet, supplemented with lyophilized powders of 1) acid milk (control), 2) milk fermented with a mixed culture of ordinary yogurt starters composed of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (SL), and 3) bifidobacterium milk fermented with the probiotic B. longum strain BL1, respectively. The bifidobacterium milk feeding brought about significant lowering of the serum concentrations of total cholesterol, low-density lipoprotein cholesterol, and triglycerides, in comparison with the control, while no change in high-density lipoprotein cholesterol concentration was observed. On the other hand, supplementation with SL milk resulted in only slight, nonsignificant decreases in serum lipid concentrations in comparison with the control. In the human study, 32 subjects with serum total cholesterol ranging from 220 to 280 mg/dl were randomly assigned to two treatments: 1) intake of a low-fat drinking yogurt prepared with ordinary yogurt starters composed of S. thermophilus and L. delbrueckii subsp. bulgaricus (P-group) and 2) intake of a low-fat drinking yogurt prepared with the two ordinary yogurt starters plus B. longum strain BL1 (B-group). After intake for 4 wk at 3 x 100 ml/day, reduction of serum total cholesterol was observed in approximately half of the B-group subjects; a particularly significant decrease in serum total cholesterol was found among subjects with moderate hypercholesterolemia (serum total cholesterol > 240 mg/dl). However, the serum lipid concentrations in the P-group subjects were almost stable during the experimental periods. The present results indicate the potential of the probiotic B. longum strain BL1 in serum lipid improvement.     

玉米、花生发酵酸奶的研制

以玉米、花生、鲜牛乳为原料，以乳酸菌和双歧杆菌为发酵菌，发酵研制了一种营养丰富、具有玉米风味和花生香味的发酵酸奶。     

无糖藜麦发酵乳的物化特性及抗氧化活性

目的：开发有益于身体健康的无糖风味发酵乳。方法：在复原乳中添加藜麦浆,以木糖醇替代蔗糖经发酵后得无糖藜麦发酵乳,以酸度、黏度、持水力等物化特性及体外抗氧化为评价指标,探究藜麦浆对无糖发酵乳的影响。结果：添加藜麦浆的发酵乳pH高于普通发酵乳,酸度、黏度、持水力则略低于普通发酵乳,且无糖藜麦发酵乳的DPPH自由基清除率（86.23%）、ABTS自由基清除率（71.32%）、羟基自由基清除率（63.27%）、Fe³⁺还原能力（0.48 mmol/L）均高于普通发酵乳。结论：添加木糖醇和藜麦浆会改变发酵乳的物化性质,同时提高发酵乳的抗氧化活性。     

利用小曲发酵生产米乳饮料的工艺研究

以大米和牛乳为原料,探究在小曲发酵得到的大米发酵液中加入牛乳制成含有牛乳的大米饮料的工艺过程。通过单因素试验研究各因素对米乳发酵饮料品质的影响,正交优化确定了制作米乳发酵饮料的最佳工艺。结果表明,其最佳工艺为接种量3%,前发酵时间6h,后发酵时间24h,牛乳的添加量为15%。利用小曲发酵生产米乳饮料最佳工艺制做的米乳发酵饮料色泽乳白,质地均一,米乳香浓厚,酒酿香味醇正,口感细腻,酸甜可口。     

Potential of functional strains, isolated from traditional Maasai milk, as starters for the production of fermented milks

The purpose of this research was the evaluation of technological features and of the ability of functional LAB strains with desirable sensory characteristics, to produce fermented milk. Eight strains of Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus paracasei and Lactococcus lactis, isolated from Maasai traditional fermented milk in Kenya and previously tested for their probiotic properties, were selected for this investigation. Technological features such as growth kinetics in fresh heat-treated whole milk medium and survival in the final product during storage at 4 degrees C, were studied. The strains Lb. acidophilus BFE 6,059, Lb. paracasei BFE 5,264 and Lc. lactis BFE 6,049 showed the best potential and were thus selected for use as starter cultures in further trials with the objective to improve their technological performance and to optimise the sensory features of fermented milk obtained. The effects of fat (F), non-fat milk solids (S) and fermentation temperature (T), modulated according to a Central Composite Design, on fermentation rates and viability losses during refrigerated storage of the chosen starters, and on product texture parameters, were studied. From the data analysis, it was possible to select optimum conditions for enhancing positive sensory traits of final products and for improving the survival of these potentially probiotic cultures.