Use of homogenisation pressure to improve quality and functionality of probiotic fermented milks containing Lactobacillus rhamnosus BFE 5264

The effects of 60‐MPa milk homogenisation treatment were investigated on the viability of the probiotic strain Lactobacillus rhamnosus BFE5264, when used as yoghurt co‐starter, as well as on the aroma profile, texture and microstructure of the resulting set‐type fermented milks. The results demonstrated that the combined use of homogenisation pressure and co‐inoculation of the probiotic strain with the traditional yoghurt starters allowed the reduction in the product coagulation time, the increase of the probiotic strain viability and the improvement of the product volatile molecule profiles. The rheological indices and the microstructure results indicated the positive effects of the milk homogenisation treatment on the product viscosity index and exopolysaccharide production.     

Isolation and characterisation of lactic acid bacteria strains from raw camel milk for potential use in the production of fermented Tunisian dairy products

The aim of this work was to study the suitability of camel milk for the production of dairy products by lactic acid fermentation. Sixty strains of lactic acid bacteria (LAB) were isolated from camel milk. The strains were tested for their acidification activity, ability to use citrate, exopolysaccharide production, lipolytic, proteolytic activities and resistance to antibiotics. Ten strains were investigated for their ability to metabolize carbohydrates and that resulted in the identification of 5 Lactococcus lactis, 1 Lactobacillus pentosus, 2 Lactobacillus plantarum, 1 Lactobacillus brevis and 1 Pediococcus pentosaceus strains. Two strains of Lactococcus lactis SCC133 and SLch14 were selected to produce traditional Tunisian fermented dairy products (Lben, Raib, Jben cheese and Smen). These strains were chosen based on their acid production capacity and their ability to produce a high yield of biomass.     

2015年内蒙古地区31批保健食品中污染菌的分离与鉴定

目的 对保健食品中的污染菌进行分离和鉴定。方法 按照GB 4789《食品安全国家标准 食品微生物学检验》对31批次保健食品进行检验, 采用全自动细菌鉴定系统对污染菌进行鉴定。结果 从31批次的保健食品中分离、鉴定出64株污染菌, 在沙门氏菌、志贺氏菌、金黄色葡萄球菌和溶血性链球菌的检验中未检出目的菌, 但分离得到致病菌和条件致病菌, 分别是阴沟肠杆菌、肺炎克雷伯菌、气味沙雷菌、温和气单胞菌、赫氏埃希菌、阪崎肠杆菌、非脱羧勒菌、泛菌属、缓慢葡萄球菌、浅绿气球菌、哥伦比亚肠球菌、腐生葡萄球菌、产色葡萄球菌、溶血葡萄球菌、铅黄肠球菌、屎肠球菌、以及枯草/解淀粉/萎缩芽孢杆菌、死谷芽孢杆菌、短小芽孢杆菌、凝结芽孢杆菌以及蜡样/苏云金/蕈状芽孢杆菌。结论 各种致病菌及条件致病菌的检出, 对消费者健康存在潜在的风险。通过分析污染菌的来源及危害, 提出提高保健食品卫生质量的建议, 为保健食品的生产、消毒灭菌、卫生学检验及监督管理等方面提供参考。     

菌种和底物因素对荔枝发酵液主要功效酶活性的影响

目的探究酵母和乳酸菌菌种及底物因素对荔枝汁发酵特性的影响。方法采用不同的酵母、乳酸菌及组合对荔枝汁进行发酵,测定发酵液中超氧化物岐化酶(SOD酶)、淀粉酶活性及总酚含量;结合单因素和Box-Benhnken设计试验进行响应面统计分析,以优化发酵底物参数工艺条件。结果荔枝汁发酵基质接入葡萄酒酵母与果酒酵母混菌(3:7,V:V),接种量为4%,25℃下发酵24 h;以保加利亚乳杆菌和嗜热链球菌菌种(8:2,V:V)混合菌种进行乳酸菌发酵,接种量为2%,37℃下发酵16 h,发酵液中SOD酶与淀粉酶活性较高。荔枝汁发酵底物优化的参数为:初始可溶性固形物含量为20°Brix,N源添加量为1.0%,pH为3.0,终发酵液的SOD酶活性可达52.17 U/mL、淀粉酶活性为12.15 U/mL、总酚含量为12.76 mg/100 mL,与模型预测值相近。结论荔枝汁通过混菌发酵,可制备具有一定功效成分的发酵饮料。     

能力验证乳粉中乳酸菌计数不确定度的评定

目的对能力验证乳粉样品中乳酸菌计数进行不确定度评定。方法依据能力验证作业指导书和GB4789.35-2010《食品安全国家标准食品微生物学检验乳酸菌检验》进行测定,再根据JJF 1059.1-2012《测量不确定度评定与表示》对不确定度来源进行分析和评定。结果乳酸菌计数过程中,分散性对结果不确定贡献较大,因此测定结果的不确定度采用检测结果的分散性进行评定。6份样品乳酸菌计数结果扩展不确定度为分别为0.02012、0.04337、0.01992、0.03296、0.02182和0.031379(P=95%,k=2.09)。结论此方法适用于类似检测条件下乳酸菌计数不确定度的评定。     

Selection of Endophytic Strains for Enhanced Bacteria-Assisted Phytoremediation of Organic Pollutants Posing a Public Health Hazard

Anthropogenic activities generate a high quantity of organic pollutants, which have an impact on human health and cause adverse environmental effects. Monitoring of many hazardous contaminations is subject to legal regulations, but some substances such as therapeutic agents, personal care products, hormones, and derivatives of common organic compounds are currently not included in these regulations. Classical methods of removal of organic pollutants involve economically challenging processes. In this regard, remediation with biological agents can be an alternative. For in situ decontamination, the plant-based approach called phytoremediation can be used. However, the main disadvantages of this method are the limited accumulation capacity of plants, sensitivity to the action of high concentrations of hazardous pollutants, and no possibility of using pollutants for growth. To overcome these drawbacks and additionally increase the efficiency of the process, an integrated technology of bacteria-assisted phytoremediation is being used recently. For the system to work, it is necessary to properly select partners, especially endophytes for specific plants, based on the knowledge of their metabolic abilities and plant colonization capacity. The best approach that allows broad recognition of all relationships occurring in a complex community of endophytic bacteria and its variability under the influence of various factors can be obtained using culture-independent techniques. However, for practical application, culture-based techniques have priority.     

Milk Coagulation Properties and Milk Protein Genetic Variants of Three Cattle Breeds/Types in Sri Lanka

Milk coagulation is the primary step in the development of most dairy products. Raw milk from individual cows and different breeds exhibit distinct coagulation capacities. This variation is largely influenced by milk protein genetic variants. The aim of the present study was to evaluate differences in coagulation properties between milk obtained from three cattle breeds/types found in Sri Lanka. A total of 90 milk samples (400 mL from each individual) were collected from two Sri Lankan cattle breeds/types (Thamankaduwa White/TW and Local/“Batu” cattle) and one European cattle breed (Friesian). Collected samples were subjected to enzymatic coagulation using commercial rennet source (Chymax®, Christian Hansen Standard, Denmark) and lactic acid bacteria (LAB) coagulation using a commercial starter culture(YFL 8 12,Christian Hansen Standard, Denmark) to determine milk coagulation properties. Different properties of milk coagulum such as yield, curd firmness, syneresis and rheological properties were evaluated. The biochemical composition (lactose, protein, fat, solid-non-fat) of milk samples were determined. Capillary Zone Electrophoresis (CZE) method was used to determine milk protein genetic variants. Experimental design was Nested Completely Randomized Design with three treatments. Milk coagulation time and curd firmness after enzymatic-coagulation were not significantly different (p>0.05) among the breeds. Coagulum yield was significantly higher (p<0.05) for the TW type than that of other breeds. Coagulum yield was negatively correlated with β-caseinA1 and α-lactalbumin in both enzymatic (-0.58) and LAB coagulation (-0.69). Coagulum yield was positively correlated (p<0.05) with β-casein B variant (0.70), protein (0.34) and lactose (0.36) contents. Meltability value was weakly and positively (p<0.05) correlated (0.34) with fat content of milk. Overall results indicate that there is a significant correlation between milk coagulation properties and milk protein genetic variants in three cattle breeds/types considered in the current study. TW type is the unique among studied breeds in terms of coagulation properties and milk protein genetic variants.     

Gemini表面活性剂的杀菌性能

采用双子表面活性剂16—4—16、十二烷基二甲基苄基氯化铵1227、异噻唑啉酮3种杀菌剂杀灭回注水中的硫酸盐还原菌（SRB）、铁细菌（FB）及腐生菌（TGB）3种细菌,并用绝迹稀释法对杀菌前后菌数进行测定。实验结果表明,杀菌剂双子表面活性剂和杀菌剂1227的杀菌效率均达到企业标准,且杀菌剂双子表面活性剂的杀菌效率达到99％以上,具有良好的耐药性,可将杀菌剂1227与杀菌剂双子表面活性剂交替应用于现场。     

乳酸菌拮抗食源性致病菌的研究及应用进展

食品在生产加工、物流运输和贮存消费过程中均可能出现被食源性致病菌污染的风险,造成安全隐患,目前通过热加工、辐照、电解水和等离子体等方法来控制食品中食源性致病菌,但在食品感官、规模化应用和安全生产等方面存在部分缺点.乳酸菌因其丰富的生物活性常作为生物发酵剂和保鲜剂广泛应用于食品中,并且可在食品中拮抗致病菌.本文主要从竞争...     

Influence of detachment procedure and diet on recovery of solid-associated bacteria from sheep ruminal digesta and representativeness of bacterial isolates as assessed by automated ribosomal intergenic spacer analysis-polymerase chain reaction

Six ruminally and duodenally cannulated sheep were used in a partially replicated 4 × 4 Latin square experiment designed to evaluate the efficiency of 3 detachment procedures (DP) to recover solid-associated bacteria (SAB) from ruminal digesta. The 4 experimental diets contained forage to concentrate (F:C) ratios of 70:30 or 30:70 with either alfalfa hay or grass hay as the forage. Bacterial biomass was labeled with ¹⁵NH₄Cl. The DP were 1) MET: digesta was incubated at 38°C for 15 min with saline solution (0.9% NaCl) containing 0.1% methylcellulose under continuous shaking; 2) STO: digesta was mixed with cold saline solution and homogenized with a stomacher for 5 min at 230 rpm; 3) FRE: digesta was immediately frozen at −20°C for 72 h, thawed at 4°C, mixed with saline solution and subjected to STO procedure. Common to all treatments was storing at 4°C for 24 h after the treatment, homogenization, filtration, and resuspension of digesta 2 times in the treatment solutions. The automated ribosomal intergenic spacer analysis of the 16S ribosomal DNA was used to analyze the similarity between bacterial communities attached to the digesta and those in the pellet obtained after each DP. There were no significant F:C × DP or forage × DP interactions for any variable. On average, STO treatment detached 65.8% of SAB from ruminal digesta, about 1.2 and 1.5 times more than FRE and MET treatments, respectively. Total recovery of SAB in STO pellets (48.9%) was greater compared with FRE (31.7%) and MET (33.1%), values being greater for high-forage compared with high-concentrate diets. Similarity index between the bacteria attached to digesta and those in the pellets were lower for FRE (48.2%) compared with MET (54.1%) and STO (54.1%), which suggests that FRE could have destroyed cell integrity of some bacterial species, thus reducing the bacterial diversity present in the pellets. The STO method was the most effective removing SAB from digesta, but only a moderate similarity between the bacterial communities attached to digesta and those recovered in the bacterial pellets was obtained. Values of duodenal microbial flow estimated using SAB as reference bacteria were greater with FRE compared with STO and MET, but all DP detected similar differences between diets, and therefore did not influence the interpretation of results.