Visible Light Photocatalytic Functional TiO2/PVDF Nanofibers for Dye Pollutant Degradation

The photodegradation of poly(vinylidene fluoride) (PVDF)/titanium oxide (TiO₂) nanofibers under visible light is described, something that has not been previously reported in the literature. Visible light photocatalytic electrospun PVDF/TiO₂ nanofiber webs with anatase TiO₂ concentration varying from 0% to 20% (0%, 1%, 3%, 5%, 10%, and 20%) are produced, and their ability to degrade a toxic pollutant, Rhodamine B (RhB), is studied. Photodegradation study using UV–vis spectroscopy on PVDF/TiO₂ nanofiber webs (with TiO₂ concentration of 20%) shows that 80% of RhB is degraded within 6 h at the wavelength of 546 nm, which clearly falls within the visible spectra. The color of RhB solvent catalyzed by PVDF/TiO₂ nanofiber webs gradually changes from red to orange, then to yellow, further to light yellow till colorless, which suggests the complete photodegradation of RhB under visible light. To estimate the rate of photodegradation, the reaction constant k is calculated. Based on the k value, PVDF/TiO₂ nanofiber webs with 20% TiO₂ concentration show the highest degradation rate compared to other PVDF/TiO₂ nanofiber webs and pure TiO₂ nanoparticles. This study proves the viability of TiO₂‐based nanofibers to have catalytic capabilities under low‐energy visible light.     

亲水相互作用色谱-串联质谱法测定液体食品中14种甜味剂

建立了亲水相互作用色谱-三重四极杆质谱（HILIC-MS/MS）同时测定液体食品中6种人工合成甜味剂和8种甜菊糖苷类天然甜味剂的分析方法。样品经Waters Xbridge Amide色谱柱（150 mm×5.0 mm,3.5 μm）分离,以乙腈-10 mmol/L甲酸铵溶液（65：35,v/v）为流动相,流速为0.4 mL/min,柱温为35℃,然后以电喷雾电离（ESI）源,在多反应监测（MRM）、负离子模式下进行三重四极杆质谱检测。14种甜味剂在各自的范围内线性关系良好,相关系数均大于0.995,检出限为0.03~0.7 mg/kg,定量限为0.1~2.2 mg/kg。在2、5和20 mg/kg添加水平下,14种甜味剂的平均回收率为80.8%~108.7%,相对标准偏差为1.5%~7.7%（n=6）。该方法样品前处理操作简单,准确度高,灵敏度高,可用于液体食品中14种甜味剂的同时测定。     

食品中99种兽药的一步式提取净化体系

建立了99种禁限用兽药的一步式提取净化体系,并通过高效液相色谱-四极杆/静电场轨道阱高分辨质谱（UHPLC-Q-Orbitrap HRMS）对其效果进行了评价。该提取净化体系基于载体辅助液液萃取技术,通过一次性前处理,完成常见的理化性质差异很大的8大类共计99种兽药残留的提取、净化工作,同时结合四极杆静电场轨道阱高分辨质谱实现了99种兽药残留的一步式多残留筛查。采用此体系对样品禁限用兽药进行测定分析,结果表明,该方法对液态乳、猪肉、鱼类等食品基质具有较强的适用性,检测的99种兽药线性范围为0.001~0.1 μg/mL,定量限为0.5~20.0 μg/kg,加标回收率为60%~120%,相对标准偏差小于15%。该方法的前处理和仪器分析过程对不同理化性质的化合物的兼容性强,检测效率高,可操作性强,检出限能满足所有受试的目标物,并且大大降低了检测成本。     

食用碱组成分析与组分含量测定的综合实验设计与教学实践

以“食用碱组成分析与各组分含量的测定”为例,开展了教学模式、组织方式、考评方法等几方面的实验教学改革,探讨了将此实验项目开设成综合设计实验的意义和实施的方法等。实践表明,将此实验项目开设成综合设计实验后,教学效果良好。     

High hydrostatic pressure inactivation of Lactobacillus plantarum cells in (O/W)-emulsions is independent from cell surface hydrophobicity and lipid phase parameters

Inactivation efficiency of high hydrostatic pressure (HHP) processing of food is strongly affected by food matrix composition. We investigated effects of fat on HHP inactivation of spoilage-associated Lactobacillus (L.) plantarum strains using defined oil-in-water (O/W)-emulsion model systems. Since fat-mediated effects on HHP inactivation could be dependent on interactions between lipid phase and microbial cells, three major factors possibly influencing such interactions were considered, that is, cell surface hydrophobicity, presence and type of surfactants, and oil droplet size. Pressure tolerance varied noticeably among L. plantarum strains and was independent of cell surface hydrophobicity. We showed that HHP inactivation of all strains tended to be more effective in presence of fat. The observation in both, surfactant-stabilized and surfactant-free (O/W)-emulsion, indicates that cell surface hydrophobicity is no intrinsic pressure resistance factor. In contrast to the presence of fat per se, surfactant type and oil droplet size did not affect inactivation efficiency.     

超高效液相色谱-串联质谱法同时测定食品中4种常用香精

建立了超高效液相色谱-串联质谱法同时测定食品中香兰素、乙基香兰素、麦芽酚和乙基麦芽酚4种香精的方法。样品用水提取,固相萃取小柱净化,目标化合物采用UPLC^TMBEH C18色谱柱(50 mm×2.1 mm, 1.7 μm)分离,以甲醇和含0.002 mol/L乙酸铵及0.1%(v/v)甲酸的水溶液为流动相进行梯度洗脱,采用电喷雾离子源电离、正离子多反应监测模式质谱检测。4种香精在5~500 μg/L或10~1000 μg/L质量浓度范围内线性良好,相关系数均在0.9995~0.9998之间;回收率为75.8%~116%,相对标准偏差(RSD, n=6)为1.58%~4.01%。该方法灵敏、准确,检测范围广,分析速度快,适合食品中香兰素、乙基香兰素、麦芽酚和乙基麦芽酚4种香精的检测。     

A Critical Review on Pulsed Electric Field: A Novel Technology for the Extraction of Phytoconstituents

Different parts of a plant (seeds, fruits, flower, leaves, stem, and roots) contain numerous biologically active compounds called “phytoconstituents” that consist of phenolics, minerals, amino acids, and vitamins. The conventional techniques applied to extract these phytoconstituents have several drawbacks including poor performance, low yields, more solvent use, long processing time, and thermally degrading by-products. In contrast, modern and advanced extraction nonthermal technologies such as pulsed electric field (PEF) assist in easier and efficient identification, characterization, and analysis of bioactive ingredients. Other advantages of PEF include cost-efficacy, less time, and solvent consumption with improved yields. This review covers the applications of PEF to obtain bioactive components, essential oils, proteins, pectin, and other important materials from various parts of the plant. Numerous studies compiled in the current evaluation concluded PEF as the best solution to extract phytoconstituents used in the food and pharmaceutical industries. PEF-assisted extraction leads to a higher yield, utilizes less solvents and energy, and it saves a lot of time compared to traditional extraction methods. PEF extraction design should be safe and efficient enough to prevent the degradation of phytoconstituents and oils.     

ATR-FTIR-MIR Spectrometry and Pattern Recognition of Bioactive Volatiles in Oily versus Microencapsulated Food Supplements: Authenticity,Quality, and Stability

Fourier transform infrared spectroscopy on the middle infrared region (ATR-FTIR-MIR) proved to be a convenient and reliable technique to evaluate foods’ quality and authenticity. Plants’ essential oils are bioactive mixtures used as such or in different oily or microencapsulated formulations, beneficial to human health. Six essential oils (thyme, oregano, juniperus, tea tree, clove, and cinnamon) were introduced in three oily formulations (Biomicin, Biomicin Forte, and Biomicin urinary) and these formulations were microencapsulated on fructose and maltodextrin matrices. To study their stability, the microencapsulated powders were kept under light irradiation for 14 days at 25 °C or introduced in biopolymer capsules. All variants were analysed by ATR-FTIR-MIR, recording wavenumbers and peak intensities (3600–650 cm⁻¹). The data were processed by Unscrambler and Metaboanalyst software, with specific algorithms (PCA, PLSDA, heatmaps, and random forest analysis). The results demonstrated that ATR-FTIR-MIR can be successfully applied for fingerprinting and finding essential oil biomarkers as well as to recognize this pattern in final microencapsulated food supplements. This study offers an improved ATR-FTIR-MIR procedure coupled with an adequate chemometric analysis and accurate data interpretation, to be applied for the evaluation of authenticity, quality, traceability, and stability during storage of essential oils incorporated in different matrices.     

对氨基苯亚甲基硫代若丹宁固相萃取分离光度法测定环境水和食品样品中的铅

合成了新试剂对氨基苯亚甲基硫代若丹宁(ABTR),并用红外光谱、核磁共振氢谱和元素分析鉴定其结构。研究了ABTR与铅的显色反应,在pH3.8的HAc NaAc缓冲介质中,吐温80存在下,ABTR与铅反应生成2∶1稳定络合物,该络合物可被WatersSep PakC18小柱固相萃取,小柱上富集的络合物用乙醇洗脱后富集倍数可达50倍,在乙醇介质中,λmax=545nm,体系摩尔吸光系数ε=1.09×105L·mol-1·cm-1。铅量在0.05～4.0μg/mL内符合比尔定律,本法可用于环境水和食品样品中铅的测定。