Antioxidant potential of extracts from peels and stems of yellow-fleshed and white cassava varieties

This study focused on the exploration of the potentials of extracting antioxidants from peels and stems of yellow-fleshed and white cassava varieties. The effect of particle size (0.2 and 0.5 mm) and variety on the phenolic content and antioxidant activity was assessed. The peels of the yellow-fleshed cassava variety with a particle size of 0.2 mm showed the highest phenolic content with 681.5 GAE mg 100 g⁻¹ and antioxidant activity of 19% and 425 μM TE g⁻¹ dry matter using DPPH and FRAP assays respectively. The stems of the white cassava with a particle size of 0.2 mm exhibited high phenolic content (442.4 GAE mg 100 g⁻¹) and antioxidant activity of 12.8% and 234 μM TE g⁻¹, better than the stem of the yellow-fleshed cassava. These results indicate that phenolic and antioxidant extractions were influenced by variety, the plant parts and particle size for the antioxidant assays.     

Hydrodistillation condition adjustment for different material particle sizes: a method to increase batch‐to‐batch quality consistency

Varying material particle sizes represent a common contributing factor to the batch‐to‐batch variation of extraction yields. To increase the batch‐to‐batch quality consistency of extracts, a method was proposed to adjust the extraction conditions for different material particle sizes, taking the hydrodistillation extraction process of Radix Curcumae and Fructus Gardeniae as a case study. Statistical models were built for five sesquiterpenes including curcumenone, curcumenol, curdione, curzerenone and furanodienone, to quantitatively describe the effects of particle size and process parameters on their extraction yields. An increase in sodium chloride concentration remarkably increased the yields of curcumenone and curcumenol, and a larger solvent‐to‐solid ratio increased the yields of five sesquiterpenes. Under the adjusted process parameters for two different particle sizes, the yield for each compound was controlled to fall in the 90–110% target range. The proposed method can be applied to various extraction processes of foods and herbal medicines.     

2-Acetyl-1-pyrroline: A key aroma component of aromatic rice and other food products

2-Acetyl-1-pyrroline is an aroma compound that gives aromatic rice its characteristic flavor. This compound either is present naturally in various food sources or is generated during certain processing methods, as reported in a number of studies. This review focuses on several sources of 2-acetyl-1-pyrroline, including aromatic rice, and the factors, including chemical and genetic parameters, affecting the formation of 2-acetyl-1-pyrroline. Extensive work has been conducted on the agricultural parameters, postharvest processing, storage, and cooking methods, influencing the concentrations of 2-acetyl-1-pyrroline in different food commodities. This article is an attempt to emphasize the importance of this compound in the food industry as a major aroma compound.     

综合改进奇异谱分解和奇异值分解的齿轮故障特征提取方法

针对齿轮故障特征微弱，在强背景噪声下难以有效提取的问题，提出了一种改进奇异谱分解（ISSD）结合奇异值分解（SVD）的齿轮故障特征提取方法。针对奇异谱分解（SSD）算法中模态参数需凭经验选取的缺陷，基于散布熵优化算法对SSD算法进行了改进，在得到既定的一组奇异谱分量的基础上，根据峭度值最大准则筛选出了最佳奇异谱分量并进行了SVD处理，采用奇异值能量标准谱自适应地确定了信号重构阶数以还原信号和提高降噪效果。最后对信号进行包络解调以提取齿轮故障特征，将所提方法运用到仿真信号和齿轮实测信号中，并同传统包络谱、SSD包络谱以及经验模态分解结合SVD(EMD-SVD)方法进行了对比分析，结果表明，所提方法的降噪和特征提取效果更佳，能够更加有效地实现齿轮故障的判别。     

Determination of four priority polycyclic aromatic hydrocarbons (4PAHs) by GC-MS in traditional Turkish yoghurts

ABSTRACT

Polycyclic aromatic hydrocarbons (PAHs) are ingested with foods and cause toxicities for humans. Yoghurt is one of the main foods that mediate PAH ingestion. Yan?k yoghurt, a traditional strained yoghurt, can contain PAHs due to its production process. Therefore, the concentration and types of four polycyclic aromatic hydrocarbons were determined by gas chromatography-mass spectrometry (GC-MS). Yan?k yoghurt samples were collected from different shops in Denizli, Turkey. For the method validation, the Eurachem guide (second edition) was adopted. Accordingly, linearity, working range, limits of detection (LOD), quantification (LOQ), precision and trueness values were set. Due to the selected validation parameters, the limit for detection was between 0.03 ng g^?1and 0.05 ng g^?1while the limit for quantification was between 0.10 ng g^?1 and 0.16 ng g^?1. Recovery rates higher than 83.80 % were obtained for four PAHs at two spiked concentrations (2.0 and 5.0 ng g^?1). Five Yan?k yoghurt samples and one commercial concentrated yoghurt sample were successfully analysed using the validated method.     

Gelation properties of goose liver protein recovered by isoelectric solubilisation/precipitation process

Isoelectric solubilisation/precipitation (ISP) process was applied to goose liver (GL) for protein extraction. The gelation properties of proteins extracted by acid processes (ACP, pH 2.0, 2.5 and 3.0) and alkaline processes (ALP, pH 11.0, 11.5 and 12.0) were estimated, where the unextracted ground GL was set as the control. Nearly 58.39~79.00% of GL proteins were recovered by ISP treatments. High molecular weight (100~250 kDa) proteins were found to be partially hydrolysed by ACP, while few changes in proteins occurred during ALP. As evidenced by rheological and textural measurements, ALP proteins formed gels with high elasticity and superior texture, whereas ACP proteins had inferior gelation properties. Moreover, ALP proteins were able to form a highly interconnected and homogeneous three‐dimensional microstructure. Predominantly, gels produced by 11.0 had optimal texture and the lowest cooking loss (P < 0.05). These results suggested that the ISP process (ALP) is a potential method to improve the economic value of GL.     

瓦斯抽采集成旁通阀二位放水器研制

针对井下瓦斯抽采中原放水器配气阀安装不规范、双截止阀使用繁琐、工人劳动强度大等现状,研制了具有集成调控装置的放水器,能够实现一个阀门控制所有气路和水路,自主放水和负压排水,从源头上杜绝了瓦斯喷孔和水流溢出等情况,大大降低了职工的劳动强度,实现了井下抽采系统安全可靠运行。     

GC-MS法测定塑胶跑道面层中的6种有害物质

建立了检测塑胶跑道面层中6种有害物质(环己基异氰酸酯(CHI)、2,4-甲苯二异氰酸酯(2,4-TDI)、2,6-甲苯二异氰酸酯(2,6-TDI)、六亚甲基二异氰酸酯(HDI)、萘-1,5-二异氰酸酯(NDI)和4,4'-二苯基甲烷二异氰酸酯(4,4'-MDI))含量的GC-MS检测方法,分别讨论了定量方式和萃取时间对6种有害物质回收率的影响。将样品剪碎至10~20目(0.85~2.00 mm)的颗粒,用10 mL乙酸乙酯萃取,室温下超声20 min,提取液用DB-17MS石英毛细管色谱柱(30 m×0.25 mm×0.25μm)分离,采用GC-MS法并选择离子检测,内标法定量。结果表明,在0.5~100.0 mg/L(4,4'-MDI在1.0~100.0 mg/L)浓度范围内,线性良好,相关系数均大于0.998,方法检出限范围为2.0~10.0 mg/kg,定量限范围为6.0~20.0 mg/kg;加标平均回收率在80.1%~100.8%之间,相对标准偏差(n=6)小于5.2%。该方法快速、准确,适用于塑胶跑道面层中有害物质的测定。