葡萄酒中木塞污染物检测技术研究进展

目前,国内葡萄酒市场日渐繁荣,葡萄酒的品质受到越来越多的关注。木塞污染是影响葡萄酒品质的常见因素之一,严重损害葡萄酒的风味。木塞污染物种类多、含量低,检测困难,建立健全葡萄酒木塞污染物检测技术体系有助于加强葡萄酒的质量安全控制,促进产业发展,同时也为相应监管能力的提升提供技术支撑。本文论述了近年来国内外葡萄酒木塞污染物的多种检测技术,重点对浓缩萃取和仪器检测方法进行了阐述,并对相应技术的优缺点进行比较,旨在为葡萄酒木塞污染物检测技术的进一步发展提供参考。     

Development and application of Multiple-Locus Variable number of tandem repeat Analysis (MLVA) to subtype a collection of Listeria monocytogenes

In this study we report the development and application of a Multiple-Locus Variable number of tandem repeat Analysis (MLVA) strategy for subtyping Listeria monocytogenes. Genome profiles of a collection of forty-five food-borne L. monocytogenes isolates were compared using MLVA. These isolates were obtained as part of an active surveillance programme of foods in the south-east region of Ireland. MLVA successfully discriminated amongst the isolates. The method was easy to perform, relatively fast and could be deployed in any molecular laboratory with basic laboratory equipment. This approach is a valuable tool, which has the capability to provide comparable results when compared with other more established typing methods, including pulsed-field gel electrophoresis (PFGE).     

Interactive Effects of Milk Fat Globule and Casein Micelle Size on the Renneting Properties of Milk

The size of the casein micelles (CM) and the milk fat globules (MFG) vary depending on farming factors, such as seasonal variation and stage of lactation, and cow genetics. The MFG and CM size of milk can influence the renneting behavior and texture of manufactured dairy products. In this work, we investigated the combined effects of MFG and CM size on the onset of gelation, the maximum rate of gelation, the value for G′_60 min (the final storage modulus) and G″_60 min (the final loss modulus), and tan δ upon renneting. Fractionation of MFG on the basis of size was carried out using laboratory-based centrifugation, whereas milk of predominantly large (184–218 nm) or small (147–159 nm) CM was selected naturally on-farm. Casein micelle size had the dominant effect on curd firmness and gelation rates of milk, where small CM milk formed rennet gels earlier and resulted in a firmer gel than milk with large CM. However, MFG size also influenced the renneting properties. The strongest rennet gels were obtained when large MFG (3.88–5.78 μm) was combined with small CM (153–159 nm). Selecting milk on the basis of the microstructure of key milk components could be achieved by natural selection of dairy cows or via fractionation technologies. Selection may provide a useful tool for efficient manufacturing of different dairy products based on the desirable characteristics specific to each.     

Derivation of multivariate indices of milk composition,coagulation properties,and curd yield in Manchega dairy sheep

This study approaches the interrelation patterns between composition of milk and whey, curd yield, chromaticity, syneresis, and technological quality of Manchega sheep milk using multivariate factor analysis. In addition, the effect of the main husbandry components (flock, prolificacy, season of the year, stage of lactation, and parity) on the common latent factors that define the pattern of variation of Manchega milk was assessed. For this purpose, 1,200 individual Manchega ewe milk samples from 4 different flocks registered under the Protected Designation of Origin Queso Manchego were analyzed (50 ewes/flock). Samples were collected in 2 different seasons of the year (spring and autumn) and at 3 time points per season: early, mid-, and late lactation. The obtained results suggested that curd yield mainly depends on milk composition, and the retention of water in the curd is related to coagulation traits. Thus, composition and moisture content could be useful indicators to assess the efficiency and quality of milk intended for cheesemaking, regardless of the analysis of coagulation properties. Finally, in terms of husbandry, a direct effect of flock and stage of lactation was observed on all analyzed factors, with a lower influence of season and parity.     

Cultured beef: from small biopsy to substantial quantity

Cultured meat is an emerging technology with the potential to solve huge challenges related to the environmental, ethical, and health implications of conventional meat production. Establishing the basic science of cultured meat has been the primary focus of the last decade but it is now feasible that cultured meat products will enter the market within the next 3 to 4 years. This proximity to market introduction demands an evaluation of aspects of the cultured meat production process that have not yet been outlined or discussed in significant detail. For example, one technological approach for the production of cultured meat uses adult muscle stem cells, the limited proliferative capacity of which necessitates repeated collection of tissue samples via biopsies of living donor animals. The selection of donor animals and the details of biopsy processes must be optimized, as this is a key bottleneck in the cultured meat production process. The number of stem cells harvested from a biopsy, together with their proliferative capacity, determines a ‘multiplicity factor’ achieved by a cultured meat production process, thus dictating the reduction in number of animals required to produce a given quantity of meat. This article considers potential scenarios for these critical upstream steps, focusing on the production of cultured beef as an example. Considerations related to donor selection and details of the biopsy process are discussed in detail. The practicalities of various scenarios for cultured beef production, the health of donor animals, and regulatory issues associated with the safety of cultured meat for consumers are also considered. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Mad2 is required for inhibiting securin and cyclin B degradation following spindle depolymerisation in meiosis I mouse oocytes

Mad2 is a pivotal component of the spindle assembly checkpoint (SAC) which inhibits anaphase promoting complex/cyclo-some (APC/C) activity by sequestering Cdc20 thereby regulating the destruction of securin and cyclin B. During mitosis, spindle depolymerisation induces a robust Mad2-dependent arrest due to inhibition of securin and cyclin B destruction. In contrast to mitosis, the molecular details underpinning the meiosis I arrest experienced by mouse oocytes exposed to spindle depolymerisation remain incompletely characterised. Notably, the role of Mad2 and the fate of the anaphase-marker, securin, are unexplored. As shown previously, we find that spindle depolymerisation by nocodazole inhibits first polar body extrusion (PBE) and stabilises cyclin B and cyclin-dependent kinase 1 activity in mouse oocytes. Here we show that stabilisation of cyclin B in nocodazole can be sustained for several hours and is associated with stabilisation of securin. These effects are SAC-mediated as, in oocytes depleted of the majority of Mad2 by morpholino antisense, securin and cyclin B are destabilised and 15% of oocytes undergo PBE. This reflects premature APC/C activation as a mutant form of cyclin B lacking its APC/C degradation signal is stable in Mad2-depleted oocytes. Moreover, homologues do not disjoin during the prolonged meiosis I arrest (> 18 h) induced by nocodaozole indicating that a non-cleavage mechanism is insufficient on its own for resolution of arm cohesion in mammalian oocytes. In conclusion, when all kinetochores lack attachment and tension, mouse oocytes mount a robust Mad2-dependent meiosis I arrest which inhibits the destruction of securin and cyclin B.     

稳定同位素、矿质元素及可见-近红外光谱技术在禽制品真实性鉴别中的应用研究进展

禽制品在食品消费中占据很大比例,近年来,禽制品掺假、造假等事件频发,禽制品真实性鉴别成为研究热点。随着掺假造假手段的多样化,传统的感官鉴别方法已经难以满足禽制品真实性鉴别的需要。近年来,现代分析仪器和技术发展迅速,现代分析方法在禽制品真实性检测中展现出优势。本文重点阐述稳定同位素技术、矿质元素指纹技术及可见-近红外光谱技术在禽制品真实性鉴别中的应用与发展趋势,旨在为我国禽制品真实性鉴别研究提供参考。     

Chemopreventive Potential of Wild Lowbush Blueberry Fruits in Multiple Stages of Carcinogenesis

ABSTRACT: Wild lowbush blueberry fruit extract was fractionated using vacuum chromatography and analyzed for chemopreventive potential using bioassays that test the ability of compounds to inhibit the initiation, promotion, and progression stages of carcinogenesis. A fraction containing phytosterols was active against the initiation stage (quinone reductase assay). However, more polar compounds were inhibitors of later stages of carcinogenesis; a fraction containing flavan-3-ols and fractions containing mainly anthocyanins, phenolic acids, flavan-3-ols, and some proanthocyanidin dimers demonstrated activity against the promotion stage (cyclooxygenase and ornithine decarboxylase assays, respectively), and a proanthocyanidin-rich fraction demonstrated antiproliferation activity (inhibition of cancerous murine hepatocyte proliferation is associated with the progression stage). These results indicate that lowbush blueberries contain a range of compounds that have bioactivity against multiple stages of carcinogenesis, and different types of phenolic compounds are active at different stages.     

Dioxins,furans, and non-ortho PCBs in Canadian Arctic seabirds

This is the first account of PCDDs, PCDFs, and non-ortho PCBs in Canadian Arctic seabirds. Livers and eggs of thick-billed murres, northern fulmars, and black-legged kittiwakes were collected in 1975 and 1993 from Prince Leopold Island in Lancaster Sound, Canada. Detectable concentrations of PCDDs, PCDFs, and non-ortho PCBs were found in all the Arctic seabird samples analyzed. Of the PCDD congeners assayed, only 2,3,7,8-substituted PCDDs were detected in the samples, whereas non-2,3,7,8-substituted PCDFs were found in addition to 2,3,7,8-substituted PCDFs in some of the samples. The predominant PCDD/F congener found in the livers of all three species was 2,3,4,7,8-PnCDF, both in 1975 and 1993. Concentrations of most dioxins and furans decreased in the fulmars and kittiwakes between 1975 and 1993 but increased in the murres. Of the non-ortho PCBs measured, PCB-126 occurred in the highest concentrations and contributed the majority of the non-ortho PCB-TEQ in all three species in both years. The highest concentrations of dioxins and furans as well as the highest TEQ values were found in the northern fulmar livers in both 1975 and 1993. Concentrations of some of the PCDDs and PCDFs are among the highest reported for Canadian Arctic biota.