九种本地雪花黄牛肉消费者感官评价及品质预测模型构建

为挖掘国内优质黄牛肉的品质特性,了解其市场定位和产品开发方向,以进口雪花牛肉作为对照,开展了9种本地A3级雪花黄牛肉生鲜肉、煎制肉和涮制肉的消费者感官评定。结果表明:郏县红牛、新疆褐牛、渤海黑牛3个品种背最长肌煎制肉从多汁性、滋味、嫩度、色泽、残渣及香气评价与进口A3级雪花牛肉无显著差异（P>0.05）,9个品种本地黄牛股二头肌涮制肉均能达到进口雪花牛肉水平,其中渤海黑牛、平凉红牛、云岭牛、夷陵牛、晋南牛股二头肌涮制肉得分显著高于进口雪花牛肉（P<0.05）。对比生鲜肉和熟制肉的感官评价结果发现二者相关性偏低（r=0.345）,说明仅凭生鲜肉外观确定牛肉质量等级存在一定的偏差,因此本研究进一步开展背最长肌理化指标的测定并与感官得分进行线性回归分析,构建了牛肉品质预测模型,结果显示生鲜肉排整体可接受性=6.382?0.132×蛋白质含量,煎制肉整体可接受性=4.751?0.228×剪切力,生鲜肉的回归方程可以解释81.2%的因变量变异,煎制肉回归方程可以解释62.6%的因变量变异,模型拟合程度良好。通过筛选蛋白质和剪切力分别作为生鲜肉和煎制肉的评定指标,为牛肉品质评价提供了新的参考依据。     

Development of an air removal system for dissolved air flotation

Dissolved Air Flotation (DAF) is often used as a separation step in drinking water treatment. An increasing use of high rate processes has become a trend in chemical treatment. When increasing the loading rate for a flotation process, an increasing head loss built up occurs in the following filter process due to dispersed air carry over. This paper describes the development of an air removal system by using a lamella plate separation system for the dispersed air. Pilot plant experiments showed that the surface load for the combination Lamella Dissolved Air Flotation, the LDAF-unit can be considerably increased in comparison with a conventional DAF-unit.     

牛奶中激素检测方法的研究进展

牛奶是人类的重要食品之一, 为人类提供蛋白、维生素、碳水化合物等营养, 其安全性一直都是社会各界关注的重点。牛奶中的激素主要分为内源性激素和外源性激素, 微量的内源性激素是牛奶中激素含量的主要来源。奶牛养殖方式及环境等因素的变化, 会对牛奶中激素含量造成影响。本文对比了国内外对牛奶中激素的限量要求, 介绍了牛奶中激素检测方法的研究进展, 包括免疫分析法、高效液相色谱法、液相色谱-串联质谱法等, 并总结了各类方法的检出限及优缺点, 提出未来应在完善牛奶激素检测技术标准, 研发高通量检测技术等方面开展深入研究, 争取实现检测过程自动化、智能化, 以提高检测效率、降低成本, 为研发精准快速的检测方法, 科学制定牛奶中激素相关限量提供参考。     

Detection of honey adulteration with beet sugar using stable isotope methodology

A usual aspect of our work involves the analysis of honey samples for later sale, following current Spanish legislation. Such analyses essentially consist of studying pollen sediments, and sensory and physicochemical analyses. With this background, it seemed appropriate to investigate possible adulterations due to the addition of sugar (beet and cane). To do this, we selected 49 samples of honey obtained from 14 floral types and used them for pollinic and sensory analyses and to detect possible adulterations due to the addition of beet sugar products (treating the oligosaccharide fraction contained in the honey with the galactose oxidase reaction) or due to corn syrup addition (with normal δ¹³C stable carbon isotope ratios). After classifying the samples according to the results of the pollen and sensory analyses, further assays were conducted. From the results it was concluded that 15% of the samples had been adulterated with beet sugar and 4% with cane sugar. The implementation of many analyses for each sample means that the results can be intercorrelated very well.     

Disposition of 14C-flumequine in sea bream (Sparus auratus) after single intraperitoneal administration

This study was conducted to evaluate the pharmacokinetics of flumequine following intraperitoneal administration of ¹⁴C-Flumequine (12 mg/kg, 100 μCi/kg) in sea bream (Sparus auratus). Three fish (147 ± 29 g) were collected at various time points ranging from 0.5 h to 144 h post administration. Absorption, distribution and elimination were studied using whole body autoradiography and liquid scintillation counting whereupon the concentration of flumequine equivalent versus time was evaluated in major organs and tissues (liver, bile, heart, brain, blood, kidney, intestine, spleen, red and white muscle). An agreement between the data obtained from whole body autoradiography and liquid scintillation counting was observed. A rapid and extensive distribution of flumequine to the major organs 0.5 h after dosing was recorded. The main route of elimination appeared to be biliary excretion due to the high concentration of radioactivity in the bile and the prolonged elimination phase compared to others tissues. The elimination of flumequine from the blood followed a two compartmental model with half life of the first phase and second phase being 0.98 h and 21.4 h respectively. The maximum flumequine recorded in blood (C_max) was 9.09 mg/kg at 0.78 h (T_max). Only traces of drugs were observed in the major tissues of the fish 72 h after administration. Based on the current results and the elimination in edible tissues in particular, flumequine seems to be an excellent treatment candidate for sea bream.     

Comparison of Chicken IgY and Mammalian IgG in Three Immunoassays for Detection of Sulfamethazine in Milk

Antibodies are the most important reagents for the development of highly sensitive and specific immunoassays to quantify analytes of interest in food and environmental samples. While immunoglobulin G (IgG)-derived antibodies from rabbit and mouse are traditionally employed in immunoassays, recent findings suggest that chicken egg yolk antibody (immunoglobulin Y (IgY)) provides several advantages over mammalian IgG. However, limited studies to date have examined the possibility of replacing IgG with IgY in immunoassays. In the current investigation, the performance of chicken IgY and IgG derived from rabbit and mouse was systematically compared in terms of sensitivity, specificity, and matrix effect under parallel conditions with three typical assay formats, specifically, indirect competitive enzyme-linked immunosorbent assay (icELISA), fluorescence polarization immunoassay (FPIA), and colloidal gold immunochromatographic assay (GICA), for detection of sulfamethazine (SMZ) as the reference molecule. We evaluated and discussed the influence of different coating antigens, tracers, and physicochemical factors on the performance of IgY and IgG in the immunoassays. Under optimized conditions, the sensitivities of icELISA (IC₅₀ values of 6.70, 4.76, and 1.66 ng mL^?1 with recoveries of 86.1–131.8% and precision of <?12%) and FPIA (IC₅₀ values of 24.79, 20.87, and 10.83 ng mL^?1 with recoveries of 81.8–120.2% and precision of <?17.3%) based on both IgY and IgG were sufficient to detect SMZ in milk while only GICA based on mouse IgG provided acceptable sensitivity. Our collective data indicate that IgY could be an acceptable alternative to mammalian antibodies in some situations (in icELISA and FPIA) for use in the development of effective immunoassays for screening and detection of veterinary drug residues in food samples.     

Development of a rapid magnetic bead-based immunoassay for sensitive detection of zearalenone

Here we demonstrate a novel magnetic bead-based enzyme-linked immunosorbent assay (MB-ELISA) for zearalenone (ZEN) detection. Firstly, an anti-ZEN monoclonal antibody (mAb) was prepared by hybridoma technique, and immobilized on carboxyl modified MBs to obtain mAb-MBs. In addition, the biotinylated ZEN-BSA was labelled by streptavidin-HRP for use as competitor. Based on the mAb-MBs and streptavidin-HRP labelled ZEN-BSA, a MB-ELISA which contains only one 20 min antigen-antibody reaction step and takes no more than 45 min for dozens of samples analysis was developed. The half maximal inhibitory concentration (IC₅₀) and limit of detection (LOD) of the MB-ELISA are 1.78 ng/mL and 0.13 ng/mL, respectively. And the MB-ELISA working range for corn samples analysis is from 5.0 μg/kg to 255.2 μg/kg. The recoveries for ZEN spiked corn samples ranged from 82.3 to 110.5% with coefficient of variation (CV) under 8.9%. For natural corn samples analysis, the results of MB-ELISA showed good agreement with the results of conventional direct competitive ELISA (R² = 0.9742).     

鸡肉香精感官评价研究

采用模糊数学法对鸡肉香精的感官质量进行综合评定,结果表明,一种鸡肉香精的综合评定级别为优,该方法能客观的做出评价结论。     

Indoor exposure levels of bacteria and fungi in residences,schools, and offices in China: A systematic review

Microbes in buildings have attracted extensive attention from both the research community and the general public due to their close relationship with human health. However, there still lacks comprehensive information on the indoor exposure level of microbes in China. This study systematically reviews exposure levels, the community structures, and the impact factors of airborne bacteria and fungi in residences, schools, and offices in China. We reviewed the major literature databases between 1980 and 2019 and selected 55 original studies based on a set of criteria. Results show that the concentration of indoor bacteria varies from 72.5 to 7500 CFU/m³, with a median value of 1000 CFU/m³, and the concentration of fungi varies from 12 to 9730 CFU/m³, with a median value of 526 CFU/m³. The concentration level of microbes varies in different climate zones, with higher bacterial concentrations in the severe cold zone, and higher fungal concentrations in the hot summer and warm winter zone. Among different buildings, classrooms have the highest average bacteria and fungi levels. This review reveals that a unified assessment system based on health effects is needed for evaluating the exposure levels of bacteria and fungi.