Effects of Lactobacillus rhamnosus GG addition in ice cream

A 2⁴ full factorial experimental design was applied to verify the effects of Lactobacillus rhamnosus GG (LGG) addition in retail-manufactured ice cream stored at two different freezing temperatures (−16°C and −28°C) and containing two different levels of sugar (15–22%) and fat (5–10%). In addition to microbial counts, the pH, acidity, viscosity of the mixes and functional properties of the ice creams were evaluated. Both fresh and frozen-thawed LGG cells underwent preliminary resistance tests to bile, antibiotics and acidity. The LGG strain proved to be highly resistant to most of the stress factors. When the micro-organism was added to ice cream mixes in a quantity of 10⁸ cfu/g, it did not change the overrun, firmness or melting behaviour of the finished product. Regardless of formulation, no count decay of LGG cells was observed in ice cream stored for up to 1 year.     

Microencapsulation of Lactobacillus rhamnosus GG by Transglutaminase Cross‐Linked Soy Protein Isolate to Improve Survival in Simulated Gastrointestinal Conditions and Yoghurt

Microencapsulation is an effective way to improve the survival of probiotics in simulated gastrointestinal (GI) conditions and yoghurt. In this study, microencapsulation of Lactobacillus rhamnosus GG (LGG) was prepared by first cross‐linking of soy protein isolate (SPI) using transglutaminase (TGase), followed by embedding the bacteria in cross‐linked SPI, and then freeze‐drying. The survival of microencapsulated LGG was evaluated in simulated GI conditions and yoghurt. The results showed that a high microencapsulation yield of 67.4% was obtained. The diameter of the microencapsulated LGG was in the range of 52.83 to 275.16 μm. Water activity did not differ between free and microencapsulated LGG after freeze‐drying. The survival of microencapsulated LGG under simulated gastric juice (pH 2.5 and 3.6), intestinal juice (0.3% and 2% bile salt) and storage at 4 °C were significantly higher than that of free cells. The survival of LGG in TGase cross‐linked SPI microcapsules was also improved to 14.5 ± 0.5% during storage in yoghurt. The microencapsulation of probiotics by TGase‐treated SPI can be a suitable alternative to polysaccharide gelation technologies.     

4种多糖益生元对鼠李糖乳杆菌微胶囊稳定性的影响

为提高鼠李糖乳杆菌（Lactobacillus rhamnosus GG,LGG）的稳定性,采用复合凝聚法制备LGG微胶囊,探究菊糖、低聚果糖、普鲁兰多糖和水苏糖4种益生元对LGG微胶囊性能的影响,并结合扫描电镜和差示扫描量热仪分析微胶囊的微结构和热稳定性。结果表明：益生元对LGG微胶囊的性能均有积极影响。模拟胃肠液处理后,菊糖活菌数存活率最高,达9.5(lg(CFU/g));水苏糖对LGG微胶囊在胆盐和高温下的保护能力最强,75℃、30 min后活菌数达8.7(lg(CFU/g));水分活度0.75条件下低聚果糖的加入提高了LGG微胶囊的贮藏稳定性;差示扫描量热分析结果表明益生元提高了LGG微胶囊的热稳定性,水苏糖的微胶囊熔融温度达172℃,但低聚果糖降低了LGG微胶囊的熔融温度;扫描电镜分析表明添加益生元后微胶囊结构没有变化。本研究为后续添加益生元对LGG微胶囊性能的影响研究提供理论基础。     

复凝聚法鼠李糖乳杆菌微胶囊工艺优化及储藏稳定性

为提高鼠李糖乳杆菌在贮藏过程中的稳定性,以明胶、阿拉伯胶为壁材,采用复凝聚法制备鼠李糖乳杆菌微胶囊。研究以湿态微胶囊的包埋率为指标,考察pH、壁材浓度、转速和菌添加量对复凝聚法微胶囊制备的影响,在单因素试验的基础上进行正交试验,优化最佳工艺。将最优条件下的湿微胶囊进行喷雾干燥和真空冷冻干燥,并在不同水分活度和不同温度条件下研究了喷雾干燥和真空冷冻干燥鼠李糖乳杆菌微胶囊的储藏稳定性。结果表明,pH 3.75、壁材浓度1.5%、转速200 r/min、菌添加量109 CFU,此条件下制备的鼠李糖乳杆菌微胶囊包埋率最高,为93.21%;复凝聚法制备的鼠李糖乳杆菌湿微胶囊干燥后,每克真空冷冻干燥微胶囊的活菌数比喷雾干燥微胶囊高1.9个对数值;储藏时水分活度越低,温度越低,鼠李糖乳杆菌微胶囊的储藏性越好;与喷雾干燥微胶囊相比,储藏时真空冷冻干燥微胶囊在高水分活度下较稳定,且在不同水分活度、不同温度条件下的活性均高于喷雾干燥微胶囊。因此复凝聚法制备的鼠李糖乳杆菌微胶囊真空冷冻干燥后能更好的保护鼠李糖乳杆菌,延长其储藏期。     

Microencapsulated Lactobacillus rhamnosus GG powders: relationship of powder physical properties to probiotic survival during storage

Freeze-dried commercial Lactobacillus rhamnosus GG (LGG) were encapsulated in an emulsion-based formulation stabilized by whey protein and resistant starch and either spray-dried or freeze-dried to produce probiotic microcapsules. There was no difference in loss of probiotics viability after spray drying or freeze drying. Particle size, morphology, moisture sorption, and water mobility of the powder microcapsules were examined. Particle size analysis and scanning electron microscopy showed that spray-dried LGG microcapsules (SDMC) were small spherical particles, whereas freeze-dried LGG microcapsules (FDMC) were larger nonspherical particles. Moisture sorption isotherms obtained using dynamic vapor sorption showed a slightly higher water uptake in spray-dried microcapsules. The effect of water mobility, as measured by nuclear magnetic resonance (NMR) spectroscopy, at various water activities (a(w) 0.32, 0.57, and 0.70) and probiotic viability during storage at 25 °C was also examined. Increasing the relative humidity of the environment at which the samples were stored caused an increase in water mobility and the rate of loss in viability. The viability data during storage indicated that SDMC had better storage stability compared to FDMC. Although more water was adsorbed for spray-dried than freeze-dried microcapsules, water mobility was similar for corresponding storage conditions because there was a stronger water-binding energy for spray-dried microcapsule. This possibly accounted for the improved survival of probiotics in spray-dried microcapsules.     

The involvement of ATPase activity in the acid tolerance of Lactobacillus rhamnosus strain GG

This study examined the survival and acid stress response of nine lactic acid bacteria (LAB) including Lactobacillus rhamnosus strain GG in commercially available yoghurt products (low pH environment) during the long‐term storage. Under the storage conditions investigated (52 weeks period at 5 °C), there was a loss of the viability of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium sp. within 35 weeks. However, L. rhamnosus strain GG, one of starter strains in a commercially available yoghurt product, exhibited excellent survival throughout the whole storage period. Our results indicate that the viability of L. rhamnosus strain GG was increased by modulating the stress‐related factors as well as the activity of ATPase with exposure to the low pH conditions.     

真菌多糖对鼠李糖乳杆菌性质的影响

研究了不同质量浓度的真菌多糖对鼠李糖乳杆菌的影响。结果表明,质量浓度为15g/L的真菌多糖对鼠李糖乳杆菌的增殖效果最显著,其活菌数最大可达到3.08×1010mL-1,能够使发酵周期提前2～3h。其产酸能力得到明显的提高,并且此真菌多糖益生元较好地提高了鼠李糖乳杆菌的耐酸、耐胆盐的能力。     

鼠李糖乳杆菌对黄曲霉毒素B1的降解及对 肝损伤的保护作用

目的分析鼠李糖乳杆菌(Lactobacillus rhamnosus GG,LGG)对黄曲霉毒素B_1(aflatoxin B_1,AFB_1)的降解能力,阐述LGG对由AFB_1引起的肝损伤的保护作用。方法利用LGG培养液、LGG上清液组、LGG菌体、热处理后上清液和热处理后LGG菌体处理AFB_1,利用高效液相色谱法测定AFB_1的残留量,分析LGG对AFB的降解能力。利用低、中和高剂量的LGG菌液灌胃由AFB_1引起肝损伤的大鼠,并以空白和阳性作为对照组,测定大鼠的血清肝功能及肝组织抗氧化指标,分析LGG对肝损伤的保护作用。结果 AFB_1降解实验表明LGG菌液对AFB_1具有显著的降解作用(P0.05),36 h能够降解(92.01±2.02)%的AFB_1。降解作用是由菌体和LGG的代谢产物共同作用的结果。大鼠血清肝功能及肝组织抗氧化指标结果表明低、中和高剂量的LGG灌胃给药均能显著改善因AFB_1引起的大鼠肝功能和肝组织抗氧化指标异常(P0.05)。结论 LGG对AFB_1具有良好的降解作用,且能够有效抑制因AFB_1引起的肝损伤。     

中药多糖对鼠李糖乳杆菌性质的影响

研究不同浓度的甘草多糖和党参多糖对鼠李糖乳杆菌的影响,发现1.5%(m/v)的党参多糖对鼠李糖乳杆菌的增殖影响最大,其活菌数最大可达到2.18×109cfu/mL,能够使其提前2～3h达到最大产酸量,缩短发酵时间,较好地提高其耐酸、耐胆盐及耐高温的能力,其多糖的利用率可高达70.5%。     

Nonfermented ice cream as a carrier for Lactobacillus acidophilus and Lactobacillus rhamnosus

Efficiency of a nonfermented ice cream for delivering Lactobacillus acidophilus and Lactobacillus rhamnosus to consumers was evaluated. Both of the microorganisms survived at the populations of greater than 10⁷ CFU g^?1 during 12 weeks of storage at ?19 °C. Addition of the microorganisms had no significant effect on the overrun, viscosity, firmness and melting behaviour; it changed the acidity, pH and sensory properties of the finished product. Resistance to acid and sensitivity to bile of both bacteria were tested separately on fresh harvested cells before inoculation to ice cream and then on the frozen‐thawed cells after 12 weeks of cold storage in ice cream. Ice cream processing followed by cold storage reduced acid resistance of both bacteria at pH 2.5. Resistance to bile in L. rhamnosus was not affected in frozen‐thawed ice cream when compared to fresh cell, whereas resistance to bile in L. acidophilus appeared to be more susceptible to the process and cold storage.     

Evaluation of aflatoxin decontaminating by two strains of Saccharomyces cerevisiae and Lactobacillus rhamnosus strain GG in pistachio nuts

In this study, the surface binding ability of Saccharomayces cerevisiae and Lactobacillus rhamnosus GG (LBGG) to aflatoxin in pistachio nuts was compared. Results showed that Saccharomayces cerevisiae and Lactobacillus rhamnosus strains had aflatoxin binding ability of 40% and 35% with initial concentration of 10 ppb and 70% and 60% with initial concentration of 20 ppb aflatoxin, respectively. Acid treatment increased this ability for yeast and bacterium to 60% and 85% in first concentration and 73% and 90% for second concentration of aflatoxin, respectively. Also, heat treatment could raise surface binding of yeast to 55% and 75% for two concentrations. In addition, heat condition for Lactobacillus improved binding to 85% and 90% for two concentrations of aflatoxin. Experiments showed that microorganism’s immobilisation on contaminated pistachio had no effect on qualitative characteristics of pistachio such as colour, texture and peroxide value.     

巯基化党参多糖对鼠李糖乳杆菌肠道黏附定植作用的影响

益生菌的肠道黏附是其实现长期肠道定植的关键因素。为增加外源性益生菌的肠道黏附性,对前期分离所得党参多糖(CPP-2)采用羧甲基化和巯基化两步化学修饰法,制备巯基化党参多糖(sC-CPP-2)。通过体外黏附实验和激光共聚焦显微镜法分析在添加sC-CPP-2情况下肠黏液对鼠李糖乳杆菌(LGG)的黏附效果,利用党参多糖及其修饰组分与海藻酸钠形成的复合薄膜,间接验证sC-CPP-2对LGG的黏附性,并利用流变仪和经典拉伸实验检测sC-CPP-2与肠道黏液之间的相互作用关系。结果表明：羧甲基党参多糖(C-CPP-2)的取代度为0.588±0.026,sC-CPP-2中巯基含量为(279.50±5.97)μmol/g, C-CPP-2经巯基化修饰后处于巯基和羧基共存状态。sC-CPP-2表面巯基可与LGG表面蛋白质上的半胱氨酸残基形成二硫键,增加LGG的肠道黏附性。sC-CPP-2与肠黏液的最大分离力为(101.82±5.78) mN,黏附总功为(120.07±6.81)μJ,二者间相互作用力增强,表观黏度变大,黏合力显著增强。sC-CPP-2能够起到连接LGG与肠黏液的中介作用,增强LGG的肠道...     

鼠李糖乳杆菌(LGG)的功能特性及其应用前景

鼠李糖乳杆菌LGG(Lactobacillus rhamnosus GG,ATCC 53103)是目前最受全球关注的益生菌之一。该菌能够耐受动物消化道环境,具有能够在人和动物肠道内定植,起到调节肠道菌群、预防和治疗腹泻、排除毒素、预防龋齿和提高机体免疫力等功能特性。     

鼠李糖乳杆菌降解亚硝酸盐影响因素研究

该试验研究鼠李糖乳杆菌降解亚硝酸盐的影响因素.研究发现,鼠李糖乳杆菌降解亚硝酸盐的最适pH值是5.0～6.0,最适温度是40℃;培养基中碳源、氮源、酵母膏、金属离子成分分别为2%葡萄糖、0.5%大豆蛋白胨、0.4%酵母膏;添加Fe2+、Fe3+、Cu2+的亚硝酸盐降解效果明显;最适接种量3%;最适培养方式为动态培养.     

具有降糖作用的鼠李糖乳杆菌生物学特性研究

本研究旨在评价一株具有降糖作用的鼠李糖乳杆菌的生物学特性。结果表明,该菌株生长较快,2 h进入生长对数期,14 h后进入稳定期,最适生长p H为5⁷,最适生长温度为37℃,最适接种量为1%²%（V/V）。此外,该菌株在强酸条件下可以生长,对人工胃肠液都具有很好的耐受性,耐受胆盐的延迟时间为0.86 h,在Na Cl浓度为9%（W/V）的培养条件下仍可以存活。更为重要的是,这株菌对Caco-2细胞具有较强的粘附能力。综上所述:该鼠李糖乳杆菌菌株可作为一株具有潜在降糖作用的发酵菌株,用以开发具有降糖作用的新型发酵产品。      

鼠李糖乳杆菌发酵及冻干保护的研究

对鼠李糖乳杆菌发酵性能和冷冻干燥存活率与保护剂、发酵时间和温度的关系进行了研究。利用液体发酵、紫外分光测量法、微量活菌计数法进行培养、测量。结果表明，鼠李糖乳杆菌发酵周期为12－16h；乳清粉和双歧因子对鼠李糖乳杆菌发酵产酸性能和细菌总数有定的影响。正交实验结果表明，10％乳清粉，15％脱脂奶粉，16h发酵时间的组合，冷冻干燥后存活的影响无显著性差异。结论：乳清粉和双歧因子在发酵后期会对鼠李糖乳杆菌的生长和发酵有促进作用可能是含糖量较高的原因。在冻干时，蛋白质（特别是酪蛋白）对细菌有保护作用。