Fat Concentration Affects Sweetness and Sensory Profiles of Sucrose, Sucralose, and Aspartame

The sensory characteristics of sucralose, aspartame, and sucrose were studied in an unflavored lipid model system varying in fat levels. One study investigated the effects of fat on the potencies (vs. sucrose) of sucralose and aspartame. We also examined absolute changes in all three sweeteners in taste, temporal, and mouthfeel properties at fiied concentrations across a wide fat range. Results indicated a modest decrease in the potencies of sucralose and aspartame across fat concentrations, especially at lower sweetness levels. All sweeteners responded similarly to changes in fat concentration. Independent of fat level, sucralose was perceived more similar to aspartame in onset, bitterness, and aftertaste, than to sucrose.     

Microbiological and physicochemical characterisation of green table olives of Halkidiki and Conservolea varieties processed by the Spanish method on industrial scale

The microbiological and physicochemical changes of industrially fermented Halkidiki and Conservolea green table olives were determined. Samples were analysed to monitor the population of lactic acid bacteria (LAB), yeasts and Enterobacteriaceae, together with changes in pH, acidity, salinity, colour, lactic acid, acetic acid and ethanol. LAB and yeast species diversity was evaluated at the beginning (1 day), middle (75 days) and final (135 days) stages of fermentation by RAPD-PCR genomic fingerprinting. Results revealed vigorous lactic acid processes as indicated by the dominance of LAB over yeasts. No Enterobacteriaceae could be detected after 30 days. Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) dominated in the beginning of fermentation in both varieties. In the end, Lactiplantibacillus pentosus (formerly Lactobacillus pentosus) and Pediococcus ethanolidurans prevailed in Halkidiki and Conservolea varieties, respectively. As for yeasts, Kluyveromyces lactis/marxianus and Pichia manshurica prevailed at the onset of fermentation in Halkidiki and Conservolea varieties, whereas in the end Pichia membranifaciens dominated in both varieties.     

应用高通量测序技术研究新疆产区葡萄果实、叶片及果园土壤微生物多样性

利用高通量测序技术分析中国新疆酿酒葡萄产区3?个葡萄园的土壤、葡萄叶片和酿酒葡萄中的微生物组成和多样性。结果表明从27?个样品中共得到1?043?102个高质量真菌序列代表,包括5?个菌门、237?个真菌菌属;共得到2?422?188?个高质量细菌序列代表,包括8?个菌门、314?个细菌菌属。无论是真菌还是细菌,土壤中微生物种类最为复杂、数量最多,其次是葡萄叶片和酿酒葡萄。土壤中真菌以Saccharomyces、Sordaria、Tetracladium和Geomyces为主,细菌以Arthrobacter、Kaistobacter和Skermanella为主;酿酒葡萄和葡萄叶片中真菌以Aureobasidium、Cryptococcus、Aspergillus和Sporospora为主,细菌以Pseudomonas、Sphingomonas和Adhaeribacter为主。葡萄园地理位置不同,微生物的多样性也存在差异。酿酒葡萄园复杂的微生物区系研究,对进一步开发产区特色微生物的筛选和利用提供了理论支持。     

基于传统分离培养和宏基因组测序分析不同产地小龙虾菌群的多样性

采用传统培养和宏基因组测序法研究浦口、太湖东山两产地小龙虾整体、表面、尾肉3个部位的初始菌群,解析其携带污染菌的差异。结果表明:浦口、太湖东山小龙虾的整体初始菌落总数差异不显著,分别为7.78 lg(CFU/g)和7.76 lg(CFU/g),而在选择性培养基上菌落数有明显差异,经16S rRNA序列鉴定,浦口小龙虾整体样品的优势菌为柠檬酸杆菌和气单胞菌,蜂房哈夫尼菌是太湖东山小龙虾整体样品的优势菌。在科水平上,宏基因组测序发现肠杆菌科肠杆菌是两产地小龙虾整体样品的优势菌;在属水平上,浦口小龙虾整体样品中的主要菌属为微小杆菌属和气单胞菌属,而太湖东山小龙虾整体样品的主要菌属为黄杆菌属、气单胞菌属和希瓦氏菌属。两产地小龙虾不同部位初始菌群的分析结果反映小龙虾潜在食品安全风险,并且不同产地的小龙虾污染菌群不同,为今后小龙虾保鲜、运输研究提供参考依据。     

复合菌系降解黄曲霉毒素B_1的效果及组成多样性研究

采用"外淘汰法"筛选了一组对黄曲霉毒素B_1(aflatoxin B_1,AFB_1)具有高效降解能力的复合菌系FBAD-2,该复合菌系在120 h内能将质量浓度为2 000μg/L的AFB_1完全降解,对质量浓度为5 000μg/L的AFB_1能降解90%。FBAD-2在30~70℃的范围内均能保持对AFB_1的高效降解能力,其最适温度为60℃。毒素降解实验分析表明,FBAD-2对AFB_1的降解主要是胞外酶的作用,其最适产酶时间为24 h,此时的胞外粗酶液在48 h内能将5 000μg/L的AFB_1完全降解。16S rDNA基因组测序分析结果表明,FBAD-2的微生物组成主要包括土芽孢杆菌(Geobacillus)、嗜热小杆菌(Symbiobacterium thermopilum)、梭菌(Clostridium)和热厌氧杆菌(Tepidanaerobacter)等。     

扩增区域对鲊广椒细菌MiSeq测序的影响

在使用引物27F/338R、338F/806R和515F/907R分别对细菌16S rRNA基因的V1～V2区、V3～V4区和V4～V5区进行扩增的基础上,采用MiSeq高通量测序评价扩增区域对鲊广椒细菌多样性分析结果的影响。结果发现,扩增16S rRNA基因V4～V5区的非特异性序列所占比例显著偏低（P＜0.05）,而扩增V1～V2区样品细菌的Chao1指数显著偏高（P＜0.05）。虽然扩增16S rRNA基因的V3～V4区会导致Cyanobacteria（蓝细菌门）和Pediococcus（小球菌）相对含量显著偏高（P＜0.05）,但不同扩增区域扩增出的同一样品其微生物群落结构无显著差异（P＞0.05）。在对鲊广椒细菌多样性进行解析时,建议选择引物515F/907R扩增16S rRNA基因的V4～V5区。     

Prevalence,Genetic Diversity,and Antibiotic Resistance of Bacillus cereus Isolated from Korean Fermented Soybean Products

Bacillus cereus contamination is a major food safety problem for Korean fermented soybean products, but few studies have assessed its potential to cause foodborne illness. The objectives of this study were to investigate the prevalence and characteristics of B. cereus isolated from Korean fermented soybean products. B. cereus was detected in 110 of 162 (67.9%) samples. The highest B. cereus frequency was observed in deonjang (68 of 93 samples, 73.1%) and cheonggukjang (18 of 25, 72.0%); however, nonhemolytic enterotoxin was detected only in 22 of 162 samples (13.6%). Although the tested B. cereus isolates showed diverse pulsotypes according to repetitive sequence‐PCR banding patterns, they displayed similar antibiotic sensitivity spectra. The low frequency of enterotoxin detection suggests that the potential risk of B. cereus foodborne illness associated with Korean fermented soybean products is lower than generally presumed. However, considering the prevalence of B. cereus and the high content of fermented soybean products in the Korean diet, it is necessary to constantly monitor the level of contamination with B. cereus and its toxins in such Korean food products.     

Prevalence,Genetic Diversity,and Technological Functions of the Lactobacillus sanfranciscensis in Sourdough: A Review

The use of sourdough as a leavening agent in bread making is a very old method that can be traced back to ancient times. Sourdoughs harbor a complex microbiota that is affected by multiple factors including factors related to cereal plants, grains, and sourdough processing techniques. Lactobacillus sanfranciscensis is the key autochthonous bacterium of the traditional sourdough microbiota and it is said to be “sourdough adapted” species. Despite the great dominance of this bacterium in sourdoughs, the origin of this species still remains unclear. Lactobacillus sanfranciscensis positively influences all aspects of sourdough and fermented foods. However, the positive influence of this species on sourdough is a strain‐dependent characteristic. The first purpose of this review was to discuss factors affecting the microbiota of sourdoughs with particular emphasis on reasons behind the remarkable prevalence of L. sanfranciscensis in this ecological niche. The second objective was to discuss the genotypic and phenotypic classification of L. sanfranciscensis strains and the influence of this species on technological and functional characteristics of sourdough including its influence on rheological properties of dough and bread characteristics, texture, aroma, and shelf‐life through the inhibition of fungal growth.     

应用Illumina MiSeq测序技术比较传统发酵乳、肉食品中细菌多样性

为全面了解内蒙古特色发酵食品中细菌微生物多样性,比较不同发酵食品的细菌群落结构。运用高通量测序技术,对发酵乳制品(饼状奶酪、棒状奶酪及奶豆腐)和发酵肉制品(发酵香肠、风干羊肉和风干牛肉)中细菌群落组成和多样性进行分析。本研究中共获得194568条有效序列,237个OTU。菌群多样性分析表明:发酵肉制品中菌群Shannon指数较高于发酵乳制品,乳肉制品之间的菌群组成差异较大。发酵乳制品中主要以厚壁菌门为主,而发酵肉制品则以厚壁菌门和变形菌门为主;在属水平上,发酵乳制品的优势菌属为乳杆菌属,而发酵肉制品中的优势菌属为假单胞菌属,次优势菌属为乳杆菌属。在种水平上,由于未检测到的菌群含量较高,所以不能确定乳、肉制品优势菌种,而在发酵乳、肉食品中可检测到的菌群中清酒乳杆菌含量较高。通过16s预测功能分析,发酵乳、肉食品中的绝大部分细菌与转运代谢有关,如脂肪代谢、氨基酸代谢等功能。     

浆水中细菌多样性分析及乳酸菌的分离鉴定

为研究自然发酵浆水中细菌的多样性并分离可以用于批量生产浆水的乳酸菌菌株,分析从3个不同地方采集的浆水中的细菌多样性,分离和鉴定浆水中对常见食源性致病菌抑菌效果好的优势菌乳酸菌。提取浆水总DNA,采用Mi Seq技术对细菌16S r RNA的V3~V4区进行测序分析,获得浆水中的细菌多样性。结果显示,乳杆菌在3种浆水中为优势菌,3种浆水中的细菌多样性存在差异,TS_taian和XA_changan 2种浆水中的细菌多样性组成比较相近,而XA_yanta则与前面2种浆水差异性比较大,在3种浆水中检测到致腐菌和可能的致病菌(或条件致病菌)。利用改良的MRS培养基从3种浆水中分离获得35株产生溶钙圈的菌株,挑选其中10株对4种常见食源性致病菌抑制效果好的菌株进行16S r RNA测序鉴定,其中8株为植物乳杆菌,2株为鼠李糖乳杆菌,说明该2种菌在浆水中为优势菌,为今后利用此两株菌进行单菌发酵或混合发酵生产浆水提供一定的理论和实践的依据。     

Sensory Characteristics of Frankfurters as Affected by Fat, Salt, and pH

Acceptable processing and flavor profile characteristics of frankfurters were achieved near a pH of 6.0. As salt increased, hardness, juiciness, saltiness, and flavor intensity scores increased. As fat increased, juiciness scores decreased (at salt levels > 1.3%) due to substitution of water for fat. In addition, increased fat resulted in decreased off-flavor. Model predictions suggested that acceptable frankfurters could be manufactured with a minimum of 11.25% fat and 1.3% salt at pH 6.0.     

人参、大蒜混合发酵过程中微生物多样性、成分及抗氧化能力分析

探究人参与大蒜混合发酵对黑参微生物多样性、成分以及生理功能的影响。以新鲜大蒜和人参为原料,采用液态发酵法自制黑蒜、黑参和参蒜,对其发酵过程中微生物多样性、主要成分以及抗氧化性进行分析。结果表明：参蒜产品的优势菌门为厚壁菌门,优势菌属为uncultured_bacterium_f_Muribaculaceae、乳杆菌属等;根据京都基因与基因组百科全书进行代谢途径预测,参蒜与大蒜和人参的代谢途径无明显差异,主要为全局及概要图、碳水化合物代谢和氨基酸代谢;参蒜的还原糖含量和总酚含量显著提高,总酸含量下降,稀有人参皂苷转化率显著提高,潜在有害物质5-羟甲基糠醛含量显著下降;参蒜具有良好的自由基清除能力。以上研究为参蒜产品的开发、促进黑参产业的发展提供理论依据。     

基于高通量测序分析感染菌核病和健康桑果内生菌群落结构及多样性

以感染菌核病桑果和健康桑果为材料,采用Illumina MiSeq高通量测序,分析二者内生菌群落结构组成及多样性变化,充分挖掘桑果内生菌资源,探讨伴生菌与菌核病病原菌互作关系,为建立桑果微生物信息系统、桑果菌核病的病原学研究以及生物防治提供参考。结果表明：根据97%的序列相似性水平,可以将细菌和真菌分别归类为281 个和259 个非重复可操作分类单元（operational taxonomic units,OTU）。内生细菌群落以蓝藻门（Cyanobacteria）、变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）、拟杆菌门（Bacteroidetes）为主,Cyanobacteria_norank、Mitochondria_norank 2 个细菌属在病果中呈明显下降趋势,敏感性较强。内生真菌群落以子囊菌门（Ascomycota）、Fungi_unclassified、担子菌门（Basidiomycota）为主,Fungi_unclassified、Basidiomycota受病原菌影响较大,其中Fungi_unclassified几乎不存在于感病组,Basidiomycota下降99.07%。内生真菌多样性可明显划分感病果实和健康果实的界限,且感病果实内生真菌多样性远小于健康果实。LEfSe显著差异分析表明,泛菌属（Pantoea）是病果中重要的细菌类群,Ascomycota及其分支锤舌菌纲（Leotiomycetes）、柔膜菌目（Helotiales）、核盘菌科（Sclerotiniaceae）和杯盘菌属（Ciboria）,粪壳菌纲（Sordariomycetes）,座囊菌纲（Dothideomycetes）,炭角菌目（Xylariales）及其分支（Xylariales_f_Xylariales_fam_Incertae_sedis,Monographella）是健康果实与感病果实间重要显著差异的生物标识。     

包装方式和贮藏温度对羊肉微生物数量、细菌多样性和代谢途径的影响

为探究包装方式和贮藏温度对羊肉微生物数量、细菌多样性和代谢途径的影响,将宰后羊肉分别经空气包装（air packaging,AP）、真空包装（vacuum packaging,VP）和贴体包装（skin packaging,SP）后置于冷藏（4±1）℃和冰温（－1.7±0.2）℃下贮藏30 d,采用平板计数和高通量测序相结合的方法对贮藏过程中的微生物群落进行分析。结果表明,贮藏过程中SP组的菌落总数（total viable count,TVC）、乳酸菌、假单胞菌等6 种菌群数量均低于AP组和VP组,冰温组6 种菌群数量均明显低于冷藏组。随贮藏时间延长羊肉菌群多样性均呈下降趋势,冷藏组较冰温组多样性更复杂。采用高通量测序技术对羊肉菌群16S rDNA的V3～V4区域测序,共获得10 个菌门和30 个菌属,所有样品中丰度最高的菌门均为变形菌门（Proteobacteria）和厚壁菌门（Firmicutes）;假单胞菌属（Pseudomonas）在AP组中为优势菌属,而在SP组和VP组中丰度较低,肉食杆菌属（Carnobacterium）、环丝菌属（Brochothrix）和乳杆菌属（Lactobacillus）均为AP、VP和SP组贮藏末期的优势菌属。基于京都基因与基因组百科全书富集分析发现碳水化合物代谢、氨基酸代谢和核苷酸代谢为羊肉贮藏过程中主要代谢途径,其中贮藏前期以氨基酸代谢为主,贮藏后期主要为碳水化合物代谢和核苷酸代谢,包装方式和贮藏温度导致的菌群结构差异主导了代谢丰度的不同。结论：SP协同冰温贮藏能够降低羊肉贮藏过程中微生物的数量和细菌群落多样性,有利于保持羊肉品质。     

Effects of soil pH on the uptake of Al,F and other elements by tea plants

Soil extractable Al, F and Zn concentrations decreased whereas extractable Ca, Cu, K, Mg, Na and P concentrations increased when the soil pH was raised from 3 to 6. These trends led to a decrease in growth of tea seedlings as determined by measurements of relative dry weight gain (RDW), relative leaf number gain (RLN) and relative leaf area gain (RLA). Tea seedlings of both ‘large‐leafed’ and ‘small‐leafed’ varieties grown in soils at pH 3 and 3.5 were the tallest and healthiest, while those at pH 6 died after 3 months. The large‐leafed variety showed higher growth rates than the small‐leafed variety. The highest (p < 0.05) amounts of Al and F, 4225 and 430 mg kg^?1 respectively, were found in seedlings under pH 3.5 treatment. When Al and F concentrations in seedlings increased, elements such as Ca, Mg, Na and Zn gently decreased (p < 0.05) whereas P increased. K and Cu were not affected. The results indicated that soil pH values higher than 4 reduced Al and F concentrations in tea plants. © 2001 Society of Chemical Industry     

基于Illumina HiSeq技术分析浆水中细菌多样性及理化性质

基于Illumina HiSeq测序平台,对陕西、甘肃浆水中细菌16S rRNA基因V3～V4区进行测序,解析其细菌群落结构多样性。结果表明,各地浆水细菌菌群结构相似,多样性较高,其中,乳酸杆菌属丰度较高,占主导地位,发酵乳杆菌、乙醇片球菌和Lactobacillus parafarraginis为优势菌,相对丰度占比分别为33.39%、21.13%、3.28%。理化性质显示,浆水液盐度范围为0.09%～0.34%,pH值为3.32～4.00,酸度为0.194～0.872 g/L,亚硝酸盐含量为5.123～10.246 mg/kg,亚硝酸盐含量均低于我国酱腌菜卫生标准。浆水中乳酸含量最高,也含有甲酸、乙酸、丙酸、丁酸等多种短链脂肪酸,蔗糖、葡萄糖、果糖含量较少。本研究揭示陕西、甘肃不同地区浆水的细菌多样性及其理化性质,为传统发酵食品研究提供一定理论基础。     

内蒙古科尔沁地区食疗用酸马奶发酵引子化学成分及细菌多样性分析

对内蒙古科尔沁地区食疗用酸马奶发酵引子部分化学指标,包括pH值、糖类、有机酸、游离脂肪酸等进行分析,同时为调查其中细菌多样性,应用Illumina MiSeq第2代测序技术测定其细菌的16S rDNA V3-V4高变区序列,分析物种的丰度、物种分布和Alpha多样性。结果：该酸马奶引子样品pH值为3.54,乳糖、半乳糖质量分数分别为（0.281±0.011）%和（0.100±0.003）%,未检测到葡萄糖;乳酸质量分数为（1.506±0.069）%,丙酸质量分数为（0.053±0.002）%,乙酸质量分数为（0.345±0.014）%,丁酸质量分数为（1.143±0.061）%;共检测到19 种脂肪酸,包括12 种饱和脂肪酸和7 种不饱和脂肪酸;不饱和脂肪酸中α-亚麻酸质量浓度最高,为（14.12±0.36）mg/L;细菌多样性检测结果表明,该样品所获优化序列为（62 082.7±4 868.8）条,可操作分类单元（operational taxonomic units,OTU）数为34.3±2.3;稀释曲线表明该测序深度充分,OTU数接近于饱和。该酸马奶引子细菌主要分布于以下4 个属：乳杆菌属（Lactobacillus）84.08%、醋杆菌属（Acetobacter）9.83%、乳球菌属（Lactococcus）2.41%、链球菌属（Streptococcus）2.18%;其优势菌属为乳杆菌属。以上结果表明,该酸马奶引子不饱和脂肪酸含量丰富,益生菌占主要地位,食品安全有保障。