食窦魏斯氏菌协同植物乳杆菌改善四川泡菜风味

探索食窦魏斯氏菌协同植物乳杆菌(协同发酵)对四川泡菜风味的影响,研究发酵过程中乳酸菌菌落总数、pH值及乳酸、乙酸、苹果酸、柠檬酸的变化;采用顶空固相微萃取结合气相色谱-质谱法,分析四川泡菜产品中挥发性物质成分及含量,并对产品感官品质进行评价。结果表明:协同发酵能够快速提升发酵前期(0～4 d)泡菜体系中乳酸菌、乳酸和乙酸的含量,改善泡菜产品发酵风味,提升产品品质。发酵第1天,协同发酵组中乳酸菌菌落总数达到8.52(lg(CFU/mL)),比植物乳杆菌组增加了0.85(lg(CFU/mL));发酵第3天,协同发酵组中乳酸质量浓度达10.9 g/L,比植物乳杆菌组增加了5.5 g/L;发酵结束后,协同发酵泡菜产品的感官优于植物乳杆菌发酵泡菜产品。挥发性物质分析表明,协同发酵组中挥发性物质达27种,比植物乳杆菌组新增7种挥发性物质;挥发性物质总量为6.096 mg/L,显著高于植物乳杆菌组(3.188 mg/L)。因此,食窦魏斯氏菌能够较好协同植物乳杆菌发酵四川泡菜,改善产品风味,表现了较好的潜在应用价值。     

3株魏斯氏菌的分离鉴定与生物学特性研究

目的 对泡菜发酵初期魏斯氏菌进行分离鉴定,并探究其安全特性和益生特性。方法 采用平板对细菌进行分离,进行分离菌株生理生化鉴定和16S rDNA测序鉴定,检测其代谢产物毒性,抗生素敏感性,耐药基因,评价细菌的耐酸、耐胆盐、耐人工肠液、黏附能力、对胆固醇及甘油三酯的降解能力、抗氧化能力以及抑菌能力。结果 共筛选出3株魏斯氏菌,命名为融合魏斯氏菌C13、食窦魏斯氏菌G232和W212; 3株菌代谢产物无毒性,对14类21种抗生素表现出不同程度耐药,耐药基因检测C13携带四环素类耐药基因(tetM), G232和W212携带磺胺类耐药基因(sulⅡ); 3株菌能耐受pH 2～4和3.0 g/L以下的胆盐,在人工肠液中3 h后存活率超过76.80%; 3株菌的黏附能力好,疏水性为60.47%～62.69%,自凝聚率为43.76%～52.55%,共凝聚率为43.20%～61.58%;对胆固醇及甘油三酯的降解主要在前15 h;表现出一定的抗氧化能力,对1,1-二苯基-2-三硝基苦肼自由基清除率较高(清除率25.69%～58.12%),对超氧阴离子自由基清除率相对较低(10.08%～35.29%); ...     

一株抗真菌食窦魏斯氏菌AT6的特性分析及培养条件优化

对食窦魏斯氏菌AT6的抑菌特性进行了研究,并采用响应面法对其培养条件进行优化。结果表明AT6发酵液在酸性pH条件下对白色念珠菌等具有较好的抑制效果,在pH4时,抑制率78%~86%。通过响应曲面优化食窦魏斯氏菌最佳培养条件为:培养基初始pH5.5,34℃条件下培养40h,其抑菌率较优化前可提高16.36%。      

四川传统泡菜中抗氧化活性食窦魏斯氏菌的筛选、鉴定及其特性分析

从不同发酵期泡姜、泡辣椒、泡蒜盐水中分离获得37株乳酸菌,以抗氧化能力为筛选指标,获得1株具有较强抗氧化能力的乳酸菌SJ14。该菌株活细胞、无细胞提取物对1,1-二苯基-2-三硝基苦肼自由基（DPPH·）和超氧阴离子自由基（O-2·）清除率分别为67.23%、35.22%和37.83%、25.66%;通过形态学、生理生化及分子遗传学鉴定,该菌株被鉴定为食窦魏斯氏菌（Weissella cibaria）;通过与植物乳杆菌N2和肠膜明串珠菌8m-9比较,表明食窦魏斯氏菌SJ14产酸能力、耐盐能力、降亚硝酸盐能力均较为突出,且与菌株N2、8m-9之间无拮抗作用。本文为多菌协同发酵泡菜提供了数据参考。      

一株抗真菌食窦魏斯氏菌AT6的特性分析及培养条件优化

对食窦魏斯氏菌AT6的抑菌特性进行了研究,并采用响应面法对其培养条件进行优化。结果表明AT6发酵液在酸性pH条件下对白色念珠菌等具有较好的抑制效果,在pH4时,抑制率78%~86%。通过响应曲面优化食窦魏斯氏菌最佳培养条件为:培养基初始pH5.5,34℃条件下培养40h,其抑菌率较优化前可提高16.36%。     

环境胁迫下食窦魏斯氏菌的耐受性评价

本研究以分离自新鲜竹笋表面的16株食窦魏斯氏菌(Weissella cibaria)为研究对象,评价其对低酸、温度和渗透压胁迫下的耐受力,筛选出具有良好耐受性的菌株,并对所得良好耐受性的菌株进行体外人工胃液和胆盐耐受力评价。结果表明,低酸、温度、渗透压胁迫下实验菌株的耐受力各不相同,综合比较得出5株食窦魏斯氏菌的耐受力均较好,分别是HSG 08、HSG 09、HSG 10、HSG 11和HSG 15。pH3.0人工胃液实验结果表明,5株食窦魏斯氏菌中,HSG 08、HSG 09和HSG 11对人工胃液中的存活率均较高,其中HSG 08的存活率最大;胆盐胁迫实验结果表明,在0.1%胆盐时,HSG 08的生长效率最高。综上所述,HSG 08在不同环境胁迫下的耐受性均较好,可用于下一步益生性食窦魏斯氏菌的研究。     

食窦魏斯氏菌SJ-02产胞外多糖发酵工艺优化

采用响应面法对影响食窦魏斯氏菌SJ-02(Weissella cibaria SJ-02)产胞外多糖(exopolysaccharides,EPS)的发酵培养基组分和发酵条件进行优化。以EPS产量为指标,首先探究培养基中碳源、氮源对EPS产量的影响,结果表明,以MRS为基础培养基,维持2%葡萄糖不变、用1.5%大豆蛋白胨替代蛋白胨,可增加菌株SJ-02的EPS产量;在单因素试验基础上采用Box-Behnken中心组合试验设计对影响EPS产量的因素进行优化,获得菌株SJ-02产EPS的最适发酵条件:接种量3.00%、培养时间34h、培养温度37℃,在此条件下理论预测EPS产量为335.03 mg/L,验证实验测得EPS产量为331.47mg/L,比未优化前提高了17%。     

食窦魏斯氏菌NCU034005与柠檬明串珠菌NCU027003对泡菜代谢物及风味的影响

在灭菌后的泡菜原材料中分别接种食窦魏斯氏菌NCU034005与柠檬明串珠菌NCU027003,室温纯种发酵7d,期间检测泡菜液中挥发性物质与非挥发性物质(葡萄糖、有机酸、氨基酸等)、pH、风味物质香气活度值。结果表明:食窦魏斯氏菌NCU034005与柠檬明串珠菌NCU027003纯种发酵泡菜中pH不同程度下降,两株乳酸菌对碳水化合物、有机酸与氨基酸的代谢能力不同;主成分分析表明食窦魏斯氏菌NCU034005与柠檬明串珠菌NCU027003纯种发酵泡菜中的代谢物与风味存在显著差异,且有自身的代表性标志代谢物与风味因子。食窦魏斯氏菌NCU034005与柠檬明串珠菌NCU027003对泡菜代谢物与风味有显著影响。     

传统馒头发酵酵子中一株优势乳酸菌CGMCC 10624的分离与鉴定

目的对分离自传统馒头发酵酵子中的一株优势乳酸菌CGMCC 10624进行多相分类学鉴定与分析。方法从馒头发酵酵子中分离、纯化得到乳酸菌CGMCC 10624,综合利用细菌形态学观察、基于细菌16S rRNA基因序列的系统发育学分析以及基于碳源代谢利用情况的生理生化特征鉴定方法,对其分类地位进行研究。结果乳酸菌菌株CGMCC 10624被鉴定为食窦魏斯氏菌(Weissella cibaria)。结论本研究分离、鉴定得到传统馒头发酵酵子中的一株优势乳酸菌,为该菌的生物学功能研究及制作包含乳酸菌和酵母菌的复合发酵菌剂奠定了资源基础。     

辣白菜中分离含内源性质粒的魏斯氏菌及其鉴定

为了探讨魏斯氏菌在辣白菜中起的作用和获得与明串珠菌相关乳酸细菌的质粒,从辣白菜中分离了魏斯氏菌。辣白菜是朝鲜民族的传统食品,在低温条件下大白菜经过乳酸细菌发酵而成的。将辣白菜汁液均匀涂布在含2%(m/v)CaCO3的MRS平板上,30℃恒温培养箱中培养24h～36h,在中国内地首次分离获得了魏斯氏菌。通过对该菌进行镜检、生理生化特性检测以及16S rDNA序列的系统发育树分析确定其分类地位。结果表明其属于Weissella cibaria,命名为kimshi006,在NCBI上的登录号为HM369807。这一魏斯氏菌菌株含有2条内源性质粒,其大小分别为大约3000bp和8000bp。     

5种菠萝果实品质比较与评价

为利用干酪乳杆菌制备发酵菠萝果汁饮品,本研究对干酪乳杆菌LK-1（Lactobacillus casei LK-1,L. casei LK-1）的生长曲线、产酸、耐酸和耐糖等特性进行研究分析,并以活菌数和总酸为指标,通过单因素实验及响应面法考察L. casei LK-1发酵菠萝果汁的最佳条件。结果表明,L. casei LK-1在pH5~7和0%~10%质量分数葡萄糖环境下,具备良好的生长繁殖能力;在酸性（pH3）和高糖（40%质量分数葡萄糖）环境中培养3 h,其存活率分别为76%和71%;在MRS培养基中培养48 h,产酸量为5.35 g/kg,产酸能力良好,适用于果汁的发酵。L. casei LK-1发酵菠萝果汁的最佳条件为：初始pH6.8,发酵温度37 ℃,接种量1%（v/v）,发酵时间30 h,此条件下制备的发酵菠萝果汁饮品活菌数为8.99±0.04 lg CFU/mL,总酸含量为7.16±0.26 g/kg,且色泽鲜亮,酸甜适口,风味较好,为L. casei LK-1在发酵食品中的进一步应用提供了理论和技术依据。

     

In situ production and analysis of Weissella confusa dextran in wheat sourdough

Several lactic acid bacteria belonging to the genera Leuconostoc, Lactobacillus, and Weissella have been introduced to wheat sourdough baking for in situ production of exopolysaccharides. This is considered a novel method for improving the shelf-life, volume and nutritional value of bread without additives. However, in situ production of exopolysaccharides during sourdough fermentation is challenged by simultaneous acidification due to metabolic activities of the bacteria, which may significantly diminish the positive technological impact of exopolysaccharides. In this study, the growth, activity and in situ production of dextran by Weissella confusa VTT E-90392 in wheat sourdoughs were investigated. Furthermore, the influence of dextran-enriched sourdoughs, at the addition level of 43%, on the subsequent bread quality was established. W. confusa efficiently produced dextran from the added sucrose in wheat sourdough without strong acid production. A new specific enzyme-assisted method for in situ analysis of dextran in sourdoughs was developed. With this method, we could for the first time proof significant (11–16 g/kg DW) production of polymeric dextran in sourdoughs. Concomitant formation of shorter isomaltooligosaccharides by W. confusa was also detected. The produced dextran significantly increased the viscosity of the sourdoughs. Application of dextran-enriched sourdoughs in bread baking provided mildly acidic wheat bread with improved volume (up to 10%) and crumb softness (25–40%) during 6 days of storage. Hence, W. confusa is a promising new strain for efficient in situ production of dextrans and isomaltooligosaccharides in sourdoughs without strong acidification.     

Isolation and characterisation of lactic acid bacteria from jiang-gua (fermented cucumbers), a traditional fermented food in Taiwan

BACKGROUND: Jiang‐gua (fermented cucumbers) is a popular traditional fermented food in Taiwan. The microflora of lactic acid bacteria (LAB) in jiang‐gua have not been investigated in detail. In this study, LAB from jiang‐gua were isolated, characterised and identified. RESULTS: A total of 103 LAB were isolated; 70 cultures were isolated from jiang‐gua samples and 33 cultures were isolated from its raw substrate, cucumber. These isolates were mainly characterised phenotypically and then divided into seven groups (A‐G) by restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. The isolates were identified as Enterococcus casseliflavus, Leuconostoc lactis, Leuconostoc mesenteroides, Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus paraplantarum, Lactococcus lactis subsp. lactis, Weissella cibaria and Weissella hellenica. The antibacterial activities of the isolates were determined and 11 Lc. lactis subsp. lactis strains showed inhibitory activity against the indicator strain Lactobacillus sakei JCM 1157^T. CONCLUSION: Heterofermentative W. cibaria and Leu. lactis were the major LAB found in jiang‐gua samples without soy sauce. In soy sauce‐added samples, homofermentative L. pentosus and L. plantarum were the most abundant LAB. In addition, the results also suggested that HhaI and RsaI restriction enzymes could be applied to distinguish W. hellenica and Weissella paramesenteroides. Copyright © 2012 Society of Chemical Industry     

Isolation and characterisation of lactic acid bacteria from yan-jiang (fermented ginger), a traditional fermented food in Taiwan

BACKGROUND: Yan‐jiang (fermented ginger) is a popular traditional fermented food in Taiwan. The lactic acid bacteria (LAB) microflora in yan‐jiang has not been studied in detail. In this study, LAB from yan‐jiang were isolated, characterised and identified. RESULTS: A total of 176 LAB were isolated; 160 cultures were isolated from yan‐jiang samples and 16 cultures were isolated from raw ginger. These isolates were characterised phenotypically and then divided into nine groups (A to I) by restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. Lactobacillus sakei and Lactococcus lactis subsp. lactis were the major LAB found in the initial 2 days of fermentation without pickled plums; these species were mostly replaced by Weissella cibaria and L. plantarum after 3 days of fermentation. In the fermentation bucket with added pickled plums, W. cibaria was the most abundant LAB found during fermentation. The antibacterial activities of the isolates were determined. Twenty‐four Lc. lactis subsp. lactis and 19 W. cibaria strains showed inhibitory activity against the indicator strain L. sakei JCM 1157^T. CONCLUSION: Results demonstrate that various LAB species were more numerous when fermentation was carried out without pickled plums. LAB also had effects on the aroma and flavour of yan‐jiang. Copyright © 2011 Society of Chemical Industry