Antioxidative ability of lactic acid bacteria

Nineteen strains of lactic acid bacteria were investigated for antioxidative activity. These includedLactobacillus acidophilus B, E, N1, 4356, LA-1, and Farr; Lactobacillus bulgaricus 12 278, 448, 449, Lb, 1006, and 11 842; Streptococcus thermophilus 821, MC, 573, 3641, and 19 987; and Bifidobacterium longum B6 and 15 708. Intracellular cell-free extract of all strains demonstrated antioxidative activity with inhibition rates of ascorbate autoxidation in the range of 7-12%. Antioxidative mechanisms including metal ion chelating ability, scavenge of reactive oxygen species, enzyme inhibition, and reducing activity of intracellular cell-free extract of lactic acid bacteria were studied. S. thermophilus 821 had the highest metal ion chelating ability for Fe(2+), and B. longum 15 708 showed the highest Cu(2+) chelating ability among the 19 strains tested. All strains demonstrated reactive oxygen species scavenging ability. L. acidophilus E showed the highest hydroxyl radical scavenging ability, and B. longum B6 had the best hydrogen peroxide scavenging ability. Reducing activity was also found in all strains. Most of the strains tested demonstrated excellent reducing activity. B. longum B6 showed the highest reducing activity among the 19 strains tested. In enzyme inhibition, superoxide dismutase activity was not found in these 19 strains, and the activity of superoxide dismutase was not induced when metal ion Mn(2+), Fe(2+), or Cu(2+)Zn(2+) was present.     

10株乳酸菌产酸性能的研究

研究表明乳酸杆菌(Lactic acid bacteria)可抑制肠道病原菌生长,具有整肠、降低血清胆固醇、增强机体免疫力、提高乳糖消化和抗肿瘤等作用[1,2]。乳酸菌还是乳制品、泡菜、发醇香肠等传统发酵食品的主要发酵剂,对传统发酵食品实行专业化、安全化生产有积极的推动作用[9]。同时,     

Enzyme immunoassay for tenuazonic acid in apple and tomato products

The Alternaria mycotoxin tenuazonic acid was derivatized with succinic anhydride and conjugated to keyhole limpet hemocyanin (KLH) and to horseradish peroxidase (HRP), respectively. The KLH conjugate was used to produce polyclonal antibodies in rabbits. A competitive direct enzyme immunoassay (EIA) for tenuazonic acid was established, which was moderately sensitive for tenuazonic acid [50% inhibition concentration (IC(50)): 320 ± 130 ng/mL] but strongly reacted with tenuazonic acid acetate (IC(50): 23.3 ± 7.5 ng/mL). Therefore, an optimized EIA protocol was established, which employed acetylation of standard and sample extract solutions. The mean standard curve detection limit (IC(30)) for tenuazonic acid acetate was 5.4 ± 2.0 ng/mL, enabling detection limits for tenuazonic acid in apple and tomato products of 25-50 ng/g (150 ng/g in tomato paste). Recoveries in a concentration range of 50-2000 ng/g were 60-130% in apple juice and tomato juice and 40-150% in other tomato products. Tenuazonic acid was detected in apple juice and tomato products from German retail shops at levels of 50-200 ng/g. In conclusion, this novel EIA for tenuazonic acid could be useful within a screening program for Alternaria mycotoxins in food.     

Rapid detection of meso-diaminopimelic acid in lactic acid bacteria by microwave cell wall hydrolysis

Two innovative microwave hydrolysis procedures for rapidly detecting meso-diaminopimelic acid in lactic acid bacteria have been developed. Whole-cell hydrolysis was performed both in liquid phase and vapor phase with 6 N HCl in sealed vessels using a microwave oven equipped with pressure and temperature probes. The presence or absence of meso-diaminopimelic acid determined by TLC, after the application of liquid- and vapor-phase microwave hydrolysis procedures, gave the same qualitative results as those obtained by traditional hydrolysis. These standardized microwave hydrolysis procedures permit a drastic reduction in hydrolysis time, from 16-20 h to less than 10 min and, consequently, in the total time of meso-diaminopimelic acid analysis (less than 90 min). Microwave hydrolysis in vapor phase is particularly convenient because, besides reducing hydrolysis time, it also eliminates the successive troublesome step of HCl removal.     

鱼菜共生系统中乳酸菌的筛选及其发酵矿化应用

针对鱼菜共生系统固体废弃物资源化利用效率低的问题,该研究旨在筛选出抗逆性好、矿化功能强的鱼源性乳酸菌,加强鱼粪残饵的发酵矿化性能。试验从鱼菜共生系统中的生物滤料和鱼体中分离乳酸菌,并通过抗逆性及发酵矿化性能检测,筛选出2株具有应用潜力的鱼粪残饵矿化菌株,经鉴定分别为乳酸乳球菌（Lactococcus lactis）L1和糊精乳杆菌（Lactobacillus dextrinicus）L2。耐温性、耐酸碱性和耐盐性检测结果显示,L1表现出较好的抗逆性。在 50 ℃时,L1存活率为96.60%,显著高于L2的存活率80.35%（P<0.05）;在pH值分别为5.0和9.0时,L1的存活率分别为65.43%和71.25%,高于L2的存活率31.10%和52.22%（P<0.05）;当盐浓度为60 g/L时,L1的存活率为37.33%,而L2无法存活。通过比较对照组（CK组,未添加乳酸菌）和乳酸乳球菌组（L组,添加乳酸乳球菌）发酵矿化过程中发酵液水质和矿物元素含量,结果显示 L组的有机物降解及矿化效果更好,除硫（S）元素以外,钾（K）、钙（Ca）、镁（Mg）、铁（Fe）、锰（Mn）和锌（Zn）元素的矿化率均在第3天达到最高（27.59%～94.67%）。综上所述,乳酸乳球菌（Lactococcus lactis）具有较强的抗逆性和显著的发酵矿化效果,且其最佳发酵矿化周期为3 d。该研究可为提高鱼菜共生系统固体废弃物资源化利用效率提供技术支持。     

添加乳酸菌和葡萄糖对苜蓿青贮品质的影响

初花期收获的苜蓿经过0h、8h和32h的晾晒(干物质含量分别为27.15%、38.45%、50.87%),添加不同含量的乳酸菌 葡萄糖(0、105cfu/g 20g/kg、106cfu/g 15g/kg、107cfu/g 10g/kg)进行青贮,其品质测定结果表明:无添加剂直接青贮时,苜蓿低水分(干物质含量为50.87%)青贮的效果最好,其青贮综合评定为82分;添加乳酸菌 葡萄糖青贮时,3种不同干物质水平中以凋萎苜蓿(干物质含量为38.45%)青贮后青贮料的青贮品质和综合评定最好;苜蓿较低干物质含量(27.15%)条件下,适中的乳酸菌和葡萄糖添加量(106cfu/g 15g/kg)可以得到最好的青贮效果和最高的综合评分;而在干物质含量为38.45%和50.87%条件下,乳酸菌和葡萄糖添加量为107cfu/g 10g/kg时,可以得到较好的青贮效果和最高的综合评分。     

产脂肪酶乳酸菌对新疆传统奶酪脂肪酸及风味的影响

为了改善奶酪品质,奶酪生产过程中通常会添加脂肪酶或者产脂肪酶乳酸菌来提升产品品质。该研究以前期筛选的4株高产脂肪酶乳酸菌为发酵剂,分别随机选取3株乳酸菌复配制作酸凝奶酪。试验组：A组T1-5和T1-3属融合魏斯氏菌（Weissella confusa）、H1-6属瑞士乳杆菌（Lactobacillus helveticus）,B组H1-6、T1-5、B2-5属植物乳杆菌（Lactobacillus plantarum）,C组H1-6、T1-3、B2-5,D组T1-3、T1-5、B2-5,对照组（E组）（添加商业发酵剂）,分析发酵剂对传统奶酪pH值、滴定酸度和脂肪氧化情况的影响,并利用气相色谱法（Gas Chromatography,GC）检测奶酪中脂肪酸变化、利用气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Chromatography,GC-IMS）分析奶酪中风味物质的变化。结果表明：A,B,C,D组4组奶酪的pH值、过氧化值（Peroxide value,POV值）明显低于E组（对照组）（P < 0.05）,A,B组奶酪滴定酸度比对照E组高（P < 0.05）;A,B,C,D组奶酪中饱和脂肪酸（Saturated Fatty Acids,SFA）含量、单不饱和脂肪酸（Monounsaturated Fatty Acids,MUFA）含量和多不饱和脂肪酸（Polyunsaturated Fatty Acids,PUFA）含量均显著高于E组（P < 0.05）;4个试验组样品中亚油酸（C18∶2n6c）含量明显高于对照组（E组）（P < 0.05）。GC-IMS及主成分分析结果显示,A、B组奶酪挥发性风味物质种类多,且相似度较高,其中2-庚酮、丁醛、乙酸丁酯是主要呈味物质;C、E两组奶酪中风味物质比较相似,风味物质主要以乙酸乙酯、乙酸丙酯、己酸乙酯等酯类为主;D组与其他4组有所差异,主要挥发性风味物质为乙酸丁酯、3-辛酮、庚醛等。结合感官评定,A、B两组奶酪整体风味和口感较好,评分较高。筛选得到的产脂肪酶乳酸菌可以作为发酵剂用于提升新疆传统奶酪品质。     

大米乳酸菌发酵降镉工艺优化

为研究乳酸发酵对大米重金属镉的脱除效果,该试验以镉超标大米为原料,采用大米发酵液进行发酵降镉,通过Plackett-Burman(PB)设计、最陡爬坡试验设计和Box-Behnken设计对发酵降镉工艺进行优化。结果表明:PB试验筛选出的对大米发酵降镉效果显著影响的因素分别为加水量、强化菌种添加量和发酵温度;根据最陡爬坡确定的各因素逼近区域进行响应面试验设计,得出最佳降镉工艺为加水量120%、强化菌种添加量0.08‰、发酵温度32℃,其他发酵条件还包括米粉发酵液添加量2%、食盐添加量0.8%、以及有效降镉时间22~26 h,就镉质量分数为0.52 mg/kg的早米,此条件下降镉率为79.24%。研究结果为乳酸发酵降镉、缓解大米镉超标问题提供参考。     

Antioxidative effects of lactic acid bacteria on the colonic mucosa of iron-overloaded mice

The antioxidative effects of lactic acid bacteria on lipid peroxidation in the colonic mucosa were investigated. Among 49 strains of lactic acid bacteria, Streptococcus thermophilus YIT 2001 showed the highest inhibitory activity against lipid peroxidation in liposomes induced by ferrous iron. Feeding a diet containing 0.4% St. thermophilus YIT 2001 (2 x 10(8) colony-forming units per mouse per day) for 2 weeks caused a significant decrease of lipid peroxide (thiobarbituric acid reactive substance) in the colonic mucosa of iron-overloaded mice (0.07% Fe in the diet). The mucosal lipid peroxide level did not correlate with the soluble iron concentration of the cecal contents. Therefore, it is suggested that the antioxidative effect of St. thermophilus YIT 2001 in the colonic mucosa was not due to the removal of ferrous iron from the reaction system of lipid peroxidation.     

高产生物膜乳酸菌抗逆性及其抗氧化特性

为了揭示乳酸菌生物膜抵抗不良环境的作用机制,该研究以2株乳酸片球菌RJ2-1-4、TG1-1-10和2株植物乳杆菌RJ1-1-4、RM1-1-11(菌株均高产生物膜)为研究对象,探究浮游态、被膜态菌株对酸、碱、胆盐、模拟人工胃肠液的耐受能力以及抗氧化能力.结果表明:在极酸条件下,菌株生长受到抑制,但是pH值3.0时,被...     

The importance of lactic acid bacteria for phytate degradation during cereal dough fermentation

Lactic acid fermentation of cereal flours resulted in a 100 (rye), 95-100 (wheat), and 39-47% (oat) reduction in phytate content within 24 h. The extent of phytate degradation was shown to be independent from the lactic acid bacteria strain used for fermentation. However, phytate degradation during cereal dough fermentation was positively correlated with endogenous plant phytase activity (rye, 6750 mU g(-1); wheat, 2930 mU g(-1); and oat, 23 mU g(-1)), and heat inactivation of the endogenous cereal phytases prior to lactic acid fermentation resulted in a complete loss of phytate degradation. Phytate degradation was restored after addition of a purified phytase to the liquid dough. Incubation of the cereal flours in buffered solutions resulted in a pH-dependent phytate degradation. The optimum of phytate degradation was shown to be around pH 5.5. Studies on phytase production of 50 lactic acid bacteria strains, previously isolated from sourdoughs, did not result in a significant production of intra- as well as extracellular phytase activity. Therefore, lactic acid bacteria do not participate directly in phytate degradation but provide favorable conditions for the endogenous cereal phytase activity by lowering the pH value.     

Aluminium phosphates as products of transformations of fertilizer phosphorus in an acid soil

The interactions of double superphosphate in an acid soddy-podzolic soil initially give rise to R-amorphous aluminium phosphates. These, however, have small admixtures of cryptocrystalline phases, indicating the beginning of the formation of aluminium phosphate minerals. Model experiments have demonstrated that minerals of the variscite group, mainly metavariscite, can be synthesized in the zone of reaction of the fertilizer P₂O₅ in an acid soil. Metavariscite, variscite and aluminium phosphates of various degrees of crystallization were studied with respect to the solubility and availability of their phosphorus to plants. The results of the experiment show metavariscite to have better solubility and higher availability to plants than variscite. Crystal aluminium phosphates seem to satisfy about 10–25% of the phosphorus needs of crops. Newly precipitated aluminophosphates have much higher availability.     

龙眼果浆复合乳酸菌发酵工艺优化

为筛选出适合龙眼发酵的复合乳酸菌,优化建立其发酵工艺,比较分析了7种不同的乳酸菌发酵龙眼的降糖能力和释放结合态酚类物质的能力,发现明串珠菌降糖能力最强,植物乳杆菌释放结合态酚能力最强。利用植物乳杆菌和明串珠菌复合发酵龙眼果肉,以游离酚质量分数和还原糖质量分数结合的综合模糊评判值为指标,通过Box-benhnken中心组合试验设计,确定复合乳酸菌发酵龙眼的最佳工艺条件。结果表明,各因素对复合乳酸菌发酵龙眼果浆的模糊评判值影响程度从强到弱依次为:发酵时间发酵温度接种量料液比。复合乳酸菌发酵龙眼的最佳工艺为:料液比为1∶7(g/m L),发酵温度为37℃,发酵时间为53 h,接种量为1.4%,菌种配比为1∶1。在最佳工艺条件下,发酵龙眼果浆的游离酚质量分数为(161.77±3.93)mg/(100 g),还原糖质量分数为(122.80±3.64)mg/g。该研究为开发低糖含量,且适合糖尿病、肥胖症等病人食用的龙眼乳酸菌发酵饮料新产品提供参考。     

产脂肪酶乳酸菌对羊肉发酵香肠脂肪酸的影响

脂肪酶在肉制品加工中会影响风味物质的积累与产生,发酵肉制品生产中常通过添加产脂肪酶菌株来改善制品的风味。通过乳酸菌在代谢过程中分解三丁酸甘油酯产生透明圈的大小,判断菌株产脂肪酶的活力,同时结合脂肪酶基因Lip0069、Lip0893表达量的变化情况,筛选产脂肪酶能力较高的乳酸菌,研究该菌株对发酵香肠中脂肪酸的影响。结果表明,瑞士乳杆菌TR1-1-3代谢过程中产酶活力最强,编码脂肪酶的基因Lip0069、Lip0893表达量最高。发酵香肠试验组共检测到34种脂肪酸,其中饱和脂肪酸（Saturated Fatty Acids, SFA）16种、单不饱和脂肪酸酸（Monounsaturated Fatty Acids, MUFA）9种和多不饱和脂肪酸（Polyunsaturated FattyAcids, PUFA）9种。含量较高的MUFA主要是油酸（C18:1C9）、棕榈油酸（C16:1）、十七碳烯酸（C17:1）、肉豆蔻烯酸（C14:1）。含量较高的PUFA主要是亚油酸（C18:2C9）、亚麻酸（C18:3N6、C18:3N3）、花生四烯酸（C20:4）、二十二碳六烯酸（C22:6,Docosahexaenoic Acid,DHA）。TR1-1-3和ZF22组发酵2 d后,MUFA的含量明显上升（P<0.05）。12 d时5个试验组MUFA的含量均达到最高,其中TR1-1-3增长比例最高,且与ZR、M组差异显著（P<0.05）。TR1-1-3组发酵2 d后PUFA的含量发生了明显的变化（P<0.05）,12 d时TR1-1-3组 PUFA的含量增长了54.17%,且与其他试验组相比差异显著（P<0.05）。乳酸菌TR1-1-3可降低产品中SFA在脂肪酸中所占比例,明显加快MUFA、PUFA的增加速度及其含量,可为研究改善香肠脂肪特性提供良好的前景。     

Potassium as an index of fruit content in baby food products. Part I. Banana-containing and apricot-containing products.

Percentage ingredient labeling has been proposed for baby foods. We determined whether or not the potassium content of baby foods could be used to verify the quantity of fruit when the characterizing ingredients were apricots or bananas, fruits rich in potassium. Official values for potassium in fruit (USDA Handbook No. 8-9) did not agree well with actual analyses. The potassium levels of products of known composition were accurately predicted from analyses of the actual ingredients used to make the foods. For banana-containing monofruit products of variable or unknown composition, potassium analysis led to fruit level estimates consistent with either the known composition or the label declaration. For products of unknown composition made with apricot concentrate, however, potassium analysis led to fruit level estimates lower than the probable fruit content. The quantity of fruit in baby foods made with potassium-rich fruits can be estimated from the potassium content if the potassium value for the fruit is representative of the actual ingredients used to make the product. If potassium analysis is to be used to verify compliance with percentage ingredient labeling, there must be statutory specification of the single-strength fruit level for fruit reconstituted from concentrate.     

Combined effect of sourdough lactic acid bacteria and additives on bread firmness and staling

The effect of various sourdoughs and additives on bread firmness and staling was studied. Compared to the bread produced with Saccharomyces cerevisiae 141, the chemical acidification of dough fermented by S. cerevisiae 141 or the use of sourdoughs increased the volume of the breads. Only sourdough fermentation was effective in delaying starch retrogradation. The effect depended on the level of acidification and on the lactic acid bacteria strain. The effect of sourdough made of S. cerevisiae 141-Lactobacillus sanfranciscensis 57-Lactobacillus plantarum 13 was improved when fungal alpha-amylase or amylolytic strains such as L. amylovorus CNBL1008 or engineered L. sanfranciscensis CB1 Amy were added. When pentosans or pentosans, endoxylanase enzyme, and L. hilgardii S32 were added to the same sourdough, a greater delay of the bread firmness and staling was found. When pentosans were in part hydrolyzed by the endoxylanase enzyme, the bread also had the highest titratable acidity, due to the fermentation of pentoses by L. hilgardii S32. The addition of the bacterial protease to the sourdough increased the bread firmness and staling.     

Antiallergic effect of milk fermented with lactic acid bacteria in a murine animal model

The objective of this study was to assess the antiallergic effect of fermented milk prepared, respectively, with Streptococcus thermophilus MC, Lactobacillus acidophilus B, Lactobacillus bulgaricus Lb, L. bulgaricus 448, and Bifidobacterium longum B6. Female BALB/c mice fed fermented milk were immunized intraperitoneally with ovalbumin (OVA)/complete Freund's adjuvant (CFA) to evaluate the immune response by observing the secretion of cytokines IL-2, IL-4, and IFN-gamma and serum antibody IgE. The results showed that supplementation with lactic acid bacteria fermented milk did not significantly change the IL-2 spontaneous and OVA-stimulated secretions of splenocytes. However, both spontaneous and OVA-stimulated secretions of splenocytes from mice fed lactic acid bacteria fermented milk showed significantly (P < 0.05) lower levels of IL-4 (Th2 cytokine) than those from OVA/CFA-immunized mice fed non-fermented milk (OVA/CFA-milk group). The spontaneous secretion of IFN-gamma (Th1 cytokine) by splenocytes from mice fed L. bulgaricus 448 or L. bulgaricus Lb fermented milk significantly increased as compared to that from the OVA/CFA-milk group. The results showed that the ratios of IFN-gamma to IL-4 of both spontaneous and OVA-stimulated secretions in splenocytes from mice fed lactic acid bacteria fermented milk increased significantly as compared to that of PBS- or OVA/CFA-milk groups. The serum levels of OVA-specific IgE in fermented milk fed groups, especially the group fed S. thermophilus MC fermented milk, were significantly lower than those in the OVA/CFA-milk group through a 6 week feeding experiment. The results showed that milk fermented with lactic acid bacteria demonstrated in vivo antiallergic effects on OVA/CFA-immunized mice via increasing the secretion ratio of IFN-gamma/IL-4 (Th1/Th2) by splenocytes and decreasing the serum level of OVA-specific IgE.     

乳酸菌发酵使木薯淀粉残渣饲料化研究

以处理木薯淀粉加工残渣,减轻环境压力为目的,对木薯渣接种乳酸菌复合系SFC-2,并添加不同量的蔗糖进行发酵,通过测定其发酵过程中的生化变化研究了其饲料化效果.结果显示:在发酵开始时接种处理的乳酸菌数为5×108,cfu/g,而对照处理没有检测到:发酵结束后,接种的3个糖水平处理的外观发酵品质比未接种处理好,但糖浓度低时丁酸积累较多,乳酸积累少,接种并添加4%蔗糖的处理乳酸积累量最高,发酵物中乳酸积累达18.7 g/kg, 接种并添加8%蔗糖的处理丁酸积累最少,仅为0.141 g/kg.相同蔗糖浓度下,接种处理的丁酸积累量均低于对照,不接种对照处理中均检测到了腐败菌分解蛋白质产生的甲胺,而接种的则没有.木薯渣材料和发酵物中的氰化物含量均远低于国家安全标准.采用乳酸菌发酵法使木薯渣饲料化是一个可行的途径.     

Honey as an indicator of heavy metal contamination

The potential use of honey as an indicator in mineral prospecting and environmental contamination studies has been investigated. Silver, Cd, Cu, and Pb levels are reported in honeys collected throughout the U.K. The elemental content of honeys was investigated in relation to that in the soils collected from within the foraging area. For samples collected over two seasons the following concentrations were found Ag <0.1 to 6.5 ng g^?1 (d.w.); Cd <0.3 to 300 ng g^?1; Cu 35 to 6510 ng g^?1; Pb <2 to 200 ng g^?1. Considerable spatial and seasonal fluctuations were apparent. No correlations were observed between honey and soil concentrations for either Cu or Pb. It is concluded that the low concentrations of heavy metals in honey and their inherent variability (due to differences in floral source, foraging range, entrapment of atmospheric particulates on the flower, etc.) detract from the reliable use of honey as a monitoring tool. The relative merits of honeybees, pollen and beeswax for environmental monitoring or biogeochemical prospecting studies are also briefly discussed.     

乳酸菌发酵技术脱除大米粉中镉的工艺优化

为了解决镉超标精米的利用问题,该试验以镉质量分数为0.6479 mg/kg的精米为原料,尝试用乳酸菌发酵技术脱除大米粉中的重金属镉,并对发酵工艺进行了优化研究。通过对比试验确定发酵菌种为植物乳杆菌和戊糖片球菌(2∶1,体积比)的混合菌,并通过单因素试验分析了大米粉粒度、发酵温度、发酵时间和接种量对镉的脱除率的影响。在固定大米粉粒度为40目的条件下,利用响应面法优化并确定的工艺参数为:发酵温度40.8℃、发酵时间23.4 h、接种量3%。在此条件下,大米粉中镉的脱除率达85.73%,在发酵后的大米粉中,镉的残留量为0.0925 mg/kg,低于国家限量标准(0.2 mg/kg)。该研究结果能有效地缓解镉超标精米的利用问题以及为工业生产提供参考数据。