Effects of dietary rosemary extract on lamb spoilage under retail display conditions

A dietary rosemary extract (RE) was tested to extend the shelf life of raw lamb meat. Lambs were supplemented with 0.6 mg kg⁻¹ RE during fattening (from 13 to 25 kg live weight). Meat spoilage (total viable counts, psycrophilic bacteria, Enterobacteriaceae, molds and yeasts), TBARS, CIE L*a*b* color and the sensory traits of lamb cuts were analyzed on days 0, 7, 14 or 21 under retail display conditions (70/30 O₂/CO₂ atmosphere, 2 °C temperature and 1600 lx lighting). Supplementation of the lamb diet with RE was effective (P < 0.05) in prolonging the time chilled-packed lamb cuts could be kept under retail display conditions. Dietary rosemary clearly inhibited lipid oxidation and rancidity, and was moderately efficient in preventing sensory deterioration and microbial spoilage. Although the results concerning meat preservation were limited, the dietary use of rosemary extracts in lambs seems to be promising as a nutritional strategy for improving meat quality.     

The effect of perspiration on photo-induced chemical reaction of azo dyes and the determination of aromatic amine products

In order to investigate the impact of perspiration on photo-induced chemical reaction of azo dyes and the carcinogenic aromatic amine products produced from the reaction, we have carried out experimental studies on the photochemical reaction of C.I. Reactive Red 2 mixed with American Association of Textile Chemists and Colorists（AATCC）standard artificial perspiration. UV-vis spectroscopic technique was employed to monitor the reaction processes, and the reaction products were analyzed by hollow fiber protected liquid-liquid-liquid phase micro-extraction with capillary electrophoresis（HF-LLLME-CE). The results showed that perspiration had remarkable influence on the photochemical reaction of azo dyes. Aromtic amines formed during the photochemical process as a result of reduction of azo dyes by organic components in perspiration. The HF-LLLME-CE methodology was validated in analyzing aromatic amines produced from the photochemical degradation of azo dye C.I. Reactive Red 2 and C.I. Acid Red 35 mixed with artificial perspiration.     

食品接触塑料中初级芳香胺检测方法研究进展

初级芳香胺是一类毒性较强的致癌物质,可通过皮肤、胃肠道和呼吸道进入人体,导致机体细胞的DNA功能和结构发生变化,严重者可引发人体输尿管癌、肾癌、膀胱癌等恶性疾病。塑料作为一种常见的食品接触材料,广泛用于食品包装、食品工具等。食品接触塑料中残留的初级芳香胺会在与食品接触的过程中向食品迁移,由此对食品安全和人身健康造成威胁。本文对国内外食品接触塑料中初级芳香胺的检测标准与相关的法规进行了对比,重点综述了近几年所报道的在食品接触塑料中初级芳香胺检测方法,包括高效液相色谱法、气相色谱.质谱法和液相色谱一质谱法等;对各种方法的前处理、仪器条件及优缺点等进行了分析;同时展望了食品接触塑料中初级芳香胺检测方法的发展趋势,以期为相关科技工作者提供参考。     

偶氮染料中微量芳香胺类的分析方法现状

为适应德国政府颁布的环保新法规的需要,作者介绍了国内外有关部门如何检测偶氮染料中微量芳香胺的方法。芳香胺的分析方法有化学分析法、分光光度法、薄层色谱法、气相色谱法、气相色谱/质谱联用法、液相色谱法和液相色谱/质谱联用法等。     

Identification of novel cytochrome P450 monooxygenases from actinomycetes capable of intermolecular oxidative C–C coupling reactions

1. Download : Download high-res image (124KB)
2. Download : Download full-size image

     

Effect of aromatic precursor addition to wine fermentations carried out with different Saccharomyces species and their hybrids

This work explores the ability of different yeast strains from different species of the genus Saccharomyces (S. cerevisiae, S. uvarum and S. kudriavzevii) and hybrids between these species to release or form varietal aroma compounds from fractions of grape odourless precursors. The de novo synthesis by the yeasts of some of the varietal aroma compounds was also evaluated. The study has shown that de novo synthesis affects some lipid derivatives, shikimic derivatives and terpenes in all species and hybrids, with some remarkable differences amongst them. The release or formation of aroma compounds from precursors was found to be strongly linked to the yeast or hybrid used, and the triple hybrid S. cerevisiae × S. bayanus × S. kudriavzevii in particular and secondarily the hybrid S. cerevisiae × S. bayanus were highly efficient in the production of most varietal aroma compounds, including γ-lactones, benzenoids, volatile phenols, vanillin derivatives and terpenols. The presence of precursors in the fermenting media caused a surprising levelling effect on the fermentative aroma composition. Altogether, these results suggest that it is possible to modulate wine aroma by employing different yeast species in order to create new wines with different aromatic notes.     

Precious metal catalysts in the clean-up of biomass gasification gas part 2: Performance and sulfur tolerance of rhodium based catalysts

Rh, Pt, and Pt-Rh catalysts on modified commercial zirconia support (m-ZrO₂) were screened for the clean-up of gasification gas from tar, methane, and ammonia both in the absence and presence of H₂S while varying the Rh metal content from 0.5 to 5 w-%. Our goal was to optimize the composition of the Rh/m-ZrO₂ catalyst in view of the production of ultra clean gas applicable for liquid biofuels synthesis. In the presence of 100 ppm sulfur, increasing Rh concentration from 0.5 to 5 w-% did not greatly improve the activity of the catalyst. The bimetallic Pt/Rh/m-ZrO₂ catalyst was also less active than the 0.5 w-% Rh/m-ZrO₂ catalyst. Furthermore, the Rh/m-ZrO₂ catalyst regained its performance at the set point of 800 °C when the sulfur feed was turned off even after exposures to 500-1000 ppm sulfur. Our data allow us to suggest that in the presence of sulfur, the active sites responsible for the reforming reactions are poisoned, but less impact occurs on sites responsible for oxidation reactions. Furthermore, the screening experiments allow to suggest that the Rh/m-ZrO₂ catalyst could be applicable to hot gas cleaning in the presence of sulfur (> 50 ppm) at above 800 °C using a moderate gas hourly space velocity of approximately 3400 1/h. Since biomass gasification gas generally contains sulfur, the 0.5 w-% Rh/m-ZrO₂ catalyst could be a promising option for gasification gas clean-up applications at temperatures above 800 °C where it reduces tar to very low levels.     

芳香族聚酯酰胺的合成方法研究

简述了聚芳酯和聚芳酰胺的优异特点,然而由于二者单独使用时存在某些不足,因此将二者进行共缩聚改性得到芳香族聚酯酰胺,它作为聚芳酯和聚芳酰胺的一种改性聚合物,兼有两者的优异性能;在多篇文献的基础上,综述了芳香族聚酯酰胺的几种比较常见的合成方法,低温溶液缩聚,界面缩聚,酯交换,混合法,还分别简要的剖析了几种合成方法的特点.由...     

Problems in the Extraction of Polycyclic Aromatic Hydrocarbons from Diesel Particulate Matter

In this work, a comparison between Soxhlet, ultrasonic, and microwave-assisted extraction (MAE) (using hexane:acetone 1:1) of polycyclic aromatic hydrocarbons (PAHs) from SRM 1650 diesel particulate matter was made. As good recoveries were not obtained for the higher molecular weight compounds, MAE with toluene and dichloromethane was also tested. Achieved recoveries were compared with the results obtained in the same assays made with SRM 1648 urban particulate matter and real atmospheric particulate samples. In order to explain the difficulty of the extraction of PAHs from SRM 1650 in comparison to SRM 1648 and real atmospheric particulate samples, elemental analysis, X-ray diffraction, and particle analysis using scanning electron microscopy coupled to an automatic computer imaging system were also made. It is important to notice that SRM 1650 shows a high percentage of carbon and differences in the morphology of the particles between SRM 1650 and SRM 1648 were observed.     

ALTERED MOBILITY OF BENZ[a]ANTHRACENE IN THE PRESENCE OF p-XYLENE AND ITS IMPACT ON RISK IN THE SUBSURFACE

Concerns over soil and groundwater contamination by PAHs have been raised as they are often introduced into the subsurface as nonaqueous-phase liquid (NAPL) mixtures. However, characterizing the risk posed by a mixture of chemicals is a challenging task due to its uncertainty in quantifying the effects of the interaction between substances. This study focuses on the effects of phase-transforming interaction on the fate, transport, and risk assessment of a PAH in a PAH - NAPL mixture. The cell test was carried out using benz[a]anthracene (BaA) and p-xylene to verify the increased mobility of highly sorbed pollutants in the presence of less sorbed, mobile liquid pollutants. The experimental results showed that BaA had greater mobility in the presence of p-xylene than in its absence. The main transport mechanisms in the vadose zone were by dissolution into p-xylene or water. The developed model showed that transport of BaA was significantly faster in the presence of NAPL, but needs improvement. As well, risk assessment indicated that the oral carcinogenic risk of BaA calculated with the concentration in groundwater was 15～ 87 times larger when mixed with NAPL than when present as a single contaminant. This study demonstrated that consideration of phase-transforming interaction is necessary to analyze the risk of a PAH - NAPL mixture. The improvement of the transport model will be the topic of our continuing research.