Raw milk traditional Italian ewe cheeses as a source of Lactobacillus casei strains with acid-bile resistance and antigenotoxic properties

Twenty-five Lactobacillus casei group strains isolated from ewe cheeses from Abruzzo region, central Italy, were identified by 16S rRNA gene sequencing, differentiated by RAPD-PCR analysis and characterized as in vitro for acid-bile tolerance and antigenotoxic properties. All the strains were very susceptible to simulated gastric fluid (pH 2.0) but most of them recovered viability (ca. 2-3 log-units) when transferred and maintained in simulated intestinal fluid (0.5% w/v bovine bile) for 3 h. Some strains showed potential for deactivating representative genotoxins as highlighted by the SOS-Chromotest. Twelve were active and nine moderately active against 4-nitroquinoline-1-oxide, and one active and only one moderately active against N-methyl-N'-nitro-N-nitrosoguanidine. The active strains produced evident spectroscopic modification of genotoxins after co-incubation. Most isolates with antigenotoxic activity resulted as acid-bile tolerant demonstrating that cheese autochthonous lactobacilli may reach the gut as a viable form and prevent genotoxin DNA damage.     

Lactobacillus role during conditioning of refrigerated and vacuum-packaged Argentinean meat

The role of Lactobacillus strains with bioprotective and technological potential on raw beef during 15days of storage under vacuum at 7°C was investigated. The assayed strains were able to grow on the meat, Lactobacillus curvatus CRL705 and Lactobacillus sakei 23K showing the highest competitiveness. A net increase of amino acids was determined in inoculated samples when compared to the control, this being maximal for Lactobacillus plantarum CRL681. Although an important endogenous activity of meat sarcoplasmic proteins was observed, the disappearance of protein bands and the generation of a new one were detected as a consequence of Lactobacillus growth. A synergistic effect of Lactobacillus in combination with the muscle proteolytic enzyme complex can be suggested. From the studied strains, the bacteriocin producer L. curvatus CRL705 may be considered as a good candidate to contribute to meat ageing by means of small peptides and free amino acids generation while improving shelf life.     

表面活性剂工业的技术进展

综述了阴离子、非离子、阳离子、两性离子娄表面活性剂及其两种主要原料(直链烷基苯磺酸盐、脂肪醇）的技术进展，概述了表面活性剂的发展方向。     

On the field trials of CIECAM97s and its model structure

The structure of the color-appearance model CIECAM97s is examined. The problems with its chromatic-adaptation transform, called the Bradford transform, are discussed in detail. The contradictions existing between the measures at various stages of CIECAM97s are described, which are ea-eb, saturation s, chroma C, and colorfulness M. The main contradictions are (1) the inversion of chromatic components between test and reference colors at different measures; and (2) the similarity between chroma and colorfulness found in the experiments done under different adapting illuminances. The structural problems in CIECAM97s are clarified by comparing its predictions with those using CIECAT94LAB, which consists of the CIE chromatic-adaptation transform published in 1994 and the CIELAB formula. © 1999 John Wiley & Sons, Inc. Col Res Appl, 24, 439–456, 1999     

EAST快控电源RT LAB半实物仿真故障分析

在RT-LAB半实物仿真平台上建立EAST快控电源主电路模型,其与外部硬件电路构成闭环反馈回路,实现EAST快控电源的功能。该硬件在环仿真实验实现了预期结果,说明RT-LAB仿真模型的可行性和准确性。文中模拟快控电源主电路中H桥的各种故障状态,通过分析故障状态下快控电源的输出电压和电流波形,形成故障状态数据波形库,为快速定位故障位置提供依据,对于快控电源的稳定运行具有重要意义。     

Biopreservation potential of lactic acid bacteria from Andean fermented food of vegetal origin

Microbial fermentations have long represented a way of natural biopreservation of raw materials, which frequently originated new food products. Among them, traditionally fermented products still manufactured by native populations all around the world are source of lactic acid bacteria (LAB) strains with high biotechnological potential. LAB are food grade microorganisms and therefore a good alternative to chemicals to be applied in food preservation. A total of 130 LAB isolates recovered from “chicha” and “tocosh”, traditional fermented Andean products of vegetal origin, were screened for antimicrobial activities against spoiler fungi Meyerozyma guilliermondii CECT 1021 (synonym Pichia guilliermondii), Penicillium roqueforti CECT 2905^NT, Aspergillus oryzae CECT 2094^NT and Aspergillus niger CECT 2807 as well as against foodborne pathogens Escherichia coli O157:H7 CECT 5947, Listeria innocua CECT 910^T and Salmonella enterica subsp. enterica serovar Typhi CECT 4138. LAB isolates represented nine species and four genera that exhibited a general inhibition of food pathogens and were also active against A. oryzae and M. guilliermondii while a poor inhibition of A. niger and P. roqueforti was produced. Antifungal activity of cell free supernatants (CFS) from seven selected strains grown in MRS was confirmed against toxigenic fungi Aspergillus parasiticus CECT 2681, Penicillium expansum CECT 2278 and Fusarium verticilloides CECT 2987 and also on the three foodborne bacteria included in the study. Phenyllactic and 3,5-Di-O-caffeoylquinic acids were identified as the predominant bioactive compounds in CFS by QuEChERS extraction with LC-MS-LIT detection approach. Four out of seven strains free of antibiotic resistances involving L. plantarum M5MA1 and M9MM1 from chicha and L. fermentum T3M3 and Lc. mesenteroides T1M3 from tocosh showed high potential to be used as biopreservatives in food applications.     

我国传统食品中乳酸菌资源的开发

我国存在着丰富的乳酸菌资源,一些少数民族地区包括内蒙古、新疆、西藏、川西高原、青海等地的牧民仍然沿用传统而古老的方法来制造各种乳制品,包括酸牛乳、酸马奶、酸驼乳、马奶酒、开菲尔等,从而使当地自然环境中的有益微生物得到了很好的保存。泡菜、腌渍菜和腊肠也是蕴藏乳酸菌的良好载体。不同来源的制品中蕴藏着不同种类的乳酸菌,这很大程度上取决于制品的制作方法和地域。传统的乳酸菌鉴定方法主要是依据其形态学及生理生化特性进行,近年来采用分子生物学方法对乳酸菌进行鉴定已有较大进展。目前对传统食品中乳酸菌菌株的鉴定存在的最大问题就是缺乏一种通用的系统或平台来鉴定不同来源的乳酸菌。     

乳酸菌在制麦和酿造中的使用对抗真菌毒素和喷涌之间的关系

乳酸菌（LAB）的代谢特性对麦芽和啤酒质量、安全性和改善风味方面有特殊的影响。本文回顾了LAB在制麦和酿造中的应用，讨论了谷物中真菌毒素的产生并回顾了它们对啤酒的影响。主要从以下几方面阐述：制麦和酿造中的LAB起子培养物；乳酸麦芽的制备；酿造过程中糖化醪和麦汁的生物酸化；酿造过程中LAB所产生的细菌素；LAB及其抗真菌活性；谷物中的真菌毒素。