Mineral Oil Hydrocarbons (MOSH/MOAH) in Edible Oils and Possible Minimization by Deodorization Through the Example of Cocoa Butter

Mineral oil hydrocarbons (MOH) are present in many fats and oils as well as foods prepared thereof. A survey of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in different types of vegetable fats and oils is reported. Contents of MOSH/MOAH were quantified using liquid chromatography online‐coupled to gas chromatography with flame‐ionization detection (LC‐GC‐FID). Cocoa butter (n = 142) showed levels from <LOQ (2.5 mg kg^?1) to 162 mg kg^?1 ΣMOSH (sum of C10–C50) and <LOQ to 55 mg kg^?1 ΣMOAH, in palm oil (n = 21) ΣMOSH were quantified from <LOQ to 124 mg kg^?1 and ΣMOAH from <LOQ to 39 mg kg^?1. Sunflower oil showed lower levels: ΣMOSH were determined in the range of <LOQ to 17 mg kg^?1 and MOAH were not observed at all. A possible influence of deodorization and a subsequent minimization of MOSH/MOAH was investigated. Systematic model‐experiments were performed on laboratory scale using spiked cocoa butter. Significant minimization of volatile MOH subfractions ≤C24 were observed at a deodorization temperature of 210 °C. Deodorization can be considered as an important processing step to reduce or even remove volatile MOSH/MOAH ≤C24. Practical Applications: Regardless of their possible entry routes into the food chain, volatile fractions of MOSH/MOAH can be removed by deodorizing vegetable fats and oils. This model‐study identifies the temperatures of deodorization that provide a significant improvement toward minimization of undesired MOSH/MOAH.     

Steam-assisted roasting inhibits formation of heterocyclic aromatic amines and alters volatile flavour profile of beef steak

In order to evaluate the effect of steam addition during meat roasting, beef sirloin steaks were cooked at five humidities (0%, 25%, 50%, 75% and 100%) under 230 °C to a centre temperature of 71 °C. With increased humidity, heating rate generally increased and the cooked steak gradually lost the typical roasted appearance. Thiobarbituric acid-reactive substances (TBARS) values generally increased, while carbonyl groups were not affected. Increased humidity promoted the formation of volatile aldehydes and alcohols, while pyrazines decreased significantly from 0% to 25% humidity. Steam-assisted roasting inhibited the formation of heterocyclic aromatic amines (HAAs; except for IQ and Norharman). However, further increase in humidity (larger than 25%) did not have additional inhibition effect. Based on the results, it is recommended to roast beef with steam addition to reduce toxic HAAs, but the humidity should be kept at a relatively low level to maintain a typical roasted appearance and flavour profile.     

基于自适应采样算法的芳烃异构化代理模型

异构化是芳烃生产中的重要环节，提高异构化环节的建模和优化效率对工业生产有着重要意义。但是，直接使用机理模型的优化过程耗时较长，优化效率低。代理模型可以有效地对机理模型进行近似，而代理模型采样方法对模型精度有很大影响。提出了一种新的基于稀疏度和最邻近期望的自适应采样算法，该方法可以平衡全局搜索和局部搜索，通过求解优化问题找到反映函数关键信息的新采样点，再加入原始样本集中，使得代理模型精度不断提高。多个测试函数结果表明，相比于其他自适应采样算法，该算法能有效提升代理模型精度和建模效率。该算法在芳烃异构化环节代理模型中也得到了有效验证，与本文中其他算法对比，该算法模型误差减少5%以上，建模时间缩短30%以上。     

Characterizations,relationship, and potential sources of outdoor and indoor particulate matter bound polycyclic aromatic hydrocarbons (PAHs) in a community of Tianjin,Northern China

Polycyclic aromatic hydrocarbons (PAHs) are among the most toxic air pollutants in China. However, because there are unsubstantial data on indoor and outdoor particulate PAHs, efforts in assessing inhalation exposure and cancer risk to PAHs are limited in China. This study measured 12 individual PAHs in indoor and outdoor environments at 36 homes during the non‐heating period and heating period in 2009. Indoor PAH concentrations were comparable with outdoor environments in the non‐heating period, but were lower in the heating period. The average indoor/outdoor ratios in both sampling periods were lower than 1, while the ratios in the non‐heating period were higher than those in the heating period. Correlation analysis and coefficient of divergence also verified the difference between indoor and outdoor PAHs, which could be caused by high ventilation in the non‐heating period. To support this conclusion, linear and robust regressions were used to estimate the infiltration factor to compare outdoor PAHs to indoor PAHs. The calculated infiltration factors obtained by the two models were similar in the non‐heating period but varied greatly in the heating period, which may have been caused by the influence of ventilation. Potential sources were distinguished using a diagnostic ratio and a mixture of coal combustion and traffic emission, which are major sources of PAHs.     

普旭真空泵在油气回收装置中的应用及维护

介绍了普旭真空泵的工艺作用、结构及工作原理,日常操作维护注意事项、常见故障及排除措施等。及时发现了设备问题,实现了设备的计划维修,使设备能够达到长周期稳定运转的目的。     

Mechanism of smoke suppression by melamine in rigid polyurethane foam

The smoke suppression of rigid polyurethane foam (RPUF) modified by melamine was investigated based on three sections: the condensed phase, the carbon layer, and the gas phase. In the condensed phase, the results of thermogravimetry, X‐ray photoelectron spectroscopy (XPS) N1S spectrum, and Fourier transform infrared spectroscopy indicated that melamine could suppress the degradation of RPUF by reacting with the aromatic hydrocarbons. It also reduced the smoke generation because the volatilizable aromatic hydrocarbons were the principal smoke precursors in a fire. In the carbon layer, the decrease from 38.50% to 24.76% of the inner layer oxygen content identified by XPS full‐spectrum and C1S spectrum indicated that melamine could prevent oxygen from transferring into the inner foam by the formation of an enhanced surface carbon layer, and the enhanced carbon layer could also block the release of smoke precursors. In the gas phase, the content of total aromatic hydrocarbons declined to 59.12% according to pyrolysis gaseous chromatography mass spectroscopy and indicated that melamine could reduce the smoke precursors. The results of smoke density chamber and cone calorimeter tests revealed that the addition of the melamine could decrease the smoke density of burning RPUF. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of a halophilic aromatic yeast together with Aspergillus oryzae in koji making on the volatile compounds and quality of soy sauce moromi

Koji making is an essential step in the production of high‐quality soy sauce. In this study, we inoculated koji with a halophilic aromatic yeast (Zygosaccharomyces rouxii) and Aspergillus oryzae and investigated the effects on the volatile compounds and quality of soy sauce moromi. Our results suggest that the optimal yeast inoculation was approximately 1.5 × 10⁶ yeast per gram of koji, and excessive yeast greatly decreased A. oryzae enzyme activity. In comparison with the control group, there were no significant changes in the concentrations of amino nitrogen, total titratable acids, total soluble nitrogen and reducing sugar by extending the fermentation time during the first fermentation month, whereas the concentration of glutamate in the yeast‐inoculated sample increased by 46.16% and the arginine concentration decreased by 61.07%. After the second fermentation month, 17, 38 and 38 volatile components were identified by GC–MS in C1, C2 and C5, respectively. Moreover, a large number of volatile components, such as 2‐Methoxy‐4‐vinylphenol, ethyl acetate and 1‐Octen‐3‐ol were found in C2 and C5. And the total contents of volatile compounds in C2 were obviously higher than C5. This work furthers our understanding of the traditional multistrain koji making and provides a new method for enhancing the quality and flavour of soy sauce.     

稠环芳烃加氢裂化机理和催化剂研究进展

稠环芳烃(PAHs)是一种化学稳定性高、难降解的有机污染物,加氢裂化可将PAHs转化为轻质芳烃和链烃,被认为是PAHs转化的有效方式之一。介绍了国内外加氢裂化工艺的概况、PAHs(萘、蒽、菲等)加氢裂化反应网络及其多相催化反应机理,分析了活性金属、酸中心、活性金属与酸中心的相互作用及助剂对加氢裂化催化剂性能的影响。提出优化金属中心和酸性中心之间的协同作用,制备出高活性、高选择性和稳定性的加氢裂化催化剂是PAHs加氢裂化催化剂的发展趋势。