Rapid and direct lodine value and saponification number determination of fats and oils by attenuated total reflectance/fourier transform infrared spectroscopy

A simple, rapid and reproducible method of determining the iodine value (IV) and saponification number (SN) for fats and oils was developed with an attenuated total reflectance/Fourier transform infrared spectrometer and commercially available triglycerides as calibration standards. Partial least squares was used to determine the spectral regions correlating with the known chemical IV and SN values, and the calibration set was augmented with additional standards generated by spectral co-adding techniques. The calibration model obtained was used to analyze commercially available fats and oils with a wide range of IV and SN values, and the results were compared to the values obtained by American Oil Chemists’ Society methods. With the spectrometer calibrated and programmed, IV and SN results could be obtained within 2–3 min per sample, a major improvement over conventional wet chemical methods.     

结晶分离技术新进展

概述了结晶分离理论和模拟优化的发展,综述了冷却剂直接接触冷却结晶、反应结晶、蒸馏-结晶耦合、氧化还原-结晶液膜、萃取结晶、磁处理结晶等结晶分离方法.合理设计结晶器及结晶工艺是实现结晶分离工业化的可靠保证,对降膜结晶装置、Bremband结晶工艺和板式结晶器进行评价.指出今后需深入进行新型结晶分离装置与工艺、工艺的工业化、结晶过程传热传质机理方面的研究.     

甲醇氧化生产甲醛装置的工艺查定及分析(Ⅰ)

对湖北省宜化股份有限公司 3 .5万t·a-1甲醛生产装置进行了物料查定 ,以工厂生产参数和分析结果为依据 ,计算了反应原料的氧醇比、水醇比、配料浓度 ,校核了反应器的选择性、转化率、收率 ,列出了物料衡算表     

Probing molecular mobility during crosslinking process of commercial resins by NMR multiexponential relaxation data analysis

In this study, we present the experimental results for the crosslinking process of a commercial polyester resin based on measurements of the spin lattice relaxation time T₁ of protons, as function of the crosslinking time evolution. Multiexponential decomposition of the evolution of magnetization measured in inversion‐recovery experiments is performed. The population of “rigid” and “mobile” nuclear spin sites was estimated as function of time evolution. In analogy to the usual monomer conversion u, site conversion from “mobile” to “rigid” sites u_M were also estimated as a function of time evolution and initial concentrations of the reagents. The multiexponential decomposition approach of T₁ relaxation data allows one to follow crosslinking processes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Evidences of the Cerium Oxide-Catalysed DPF Regeneration in a Real Diesel Engine Exhaust

The active phase Ce_0.5Pr_0.5O₂ has been loaded on commercial substrates (SiC DPF and cordierite honeycomb monolith) to perform DPF regeneration experiments in the exhaust of a diesel engine. Also, a powder sample has been prepared to carry out soot combustion experiments at laboratory. Experiments performed in the real diesel exhaust demonstrated the catalytic activity of the Ce–Pr mixed oxide for the combustion of soot, lowering the DPF regeneration temperature with regard to a counterpart catalyst-free DPF. The temperature for active regeneration of the Ce_0.5Pr_0.5O₂-containing DPF when the soot content is low is in the range of 500–550 °C. When the Ce_0.5Pr_0.5O₂-containing DPF is saturated with a high amount of soot, pressure drop and soot load at the filter reach equilibrium at around 360 °C under steady state engine operation due to passive regeneration. The uncoated DPF reached this equilibrium at around 440 °C. Comparing results at real exhaust with those at laboratory allow concluding that the Ce_0.5Pr_0.5O₂-catalysed soot combustion in the real exhaust is not based on the NO₂-assisted mechanism but is most likely occurring by the active oxygen-based mechanism.     

Flue gas cleaning in power stations by using electron beam technology. Influence on PAH emissions

The electron beam technology (EBT), proven treatment for SO₂ and NO_x removal, is applied to different power stations as hot gas cleaning system. In this paper, an assessment of this technique installed in a Bulgarian power station on organic emissions is analyzed. The Polycyclic Aromatic Hydrocarbons (PAH) content, not only emitted in the gas phase but also trapped in the solid phase, has been carried out before and after the irradiation. The main aim has been to know whether the EBT affects organic emissions, like PAH, as it happens with inorganic pollutants, like SO₂ and NO_x, studying EBT effects from an organic environmental point of view.     

Changes in the milk and cheese fat composition of ewes fed commercial supplements containing linseed with special reference to the CLA content and isomer composition

A study was carried out to increase the CLA contents in ewes’ milk fat under field conditions by dietary means and to investigate the extent of the changes and consequences for milk processing and cheese quality. During a 3-mon period, ewes’ bulk milk samples were collected every week from two different herds. For the first 4 wk the ewes were fed a conventional diet. Then the following 6 wk a supplement enriched in α-linolenate (whole linseed) was incorporated into the ovine diet. Finally, in the last 3 wk the feeding was the same as in the first 4 wk. The FA profile in milk fat was monitored by GC, and the distribution of CLA isomers was thoroughly tested by combining GC-MS of 4,4-dimethyloxazoline derivatives (DMOX) with silver ion-HPLC (Ag⁺-HPLC) of FAME. Reconstructed mass spectral profiles of CLA characteristic ions from DMOX were used to identify positional isomers, and Ag⁺-HPLC was used to quantify them. An increase in total CLA in milk fat was observed, and total CLA remained elevated during the weeks of enriched α-linolenate feeding. In our experimental conditions there was a linear relationship between trans-vaccenic acid (trans-11-octadecenoic acid; trans-11 18∶1) and 9-cis, 11-trans CLA in ewes’ milk fat. Concerning the CLA isomer profile, increases in the 11,13- and 12,14–18∶2 positional isomers were considerable when linseed was included in the diet. Organoleptic characteristics of cheeses made with CLA-enriched milk did not substantially differ from those made with nonsupplemented ewes’ milk. CLA total content and isomer profile did not change during ripening.     

Effect of pasture vs. concentrate diet on CLA isomer distribution in different tissue lipids of beef cattle

This study examined the effects of feeding pasture vs. concentrate on the distribution of CLA isomers in the lipids of longissimus and semitendinosus muscle, liver and heart muscle, and subcutaneous fat in beef bulls. Sixty-four German Holstein and German Simmental bulls were randomly allocated to either an indoor concentrate system or periods of pasture feeding followed by a finishing period on a concentrate containing linseed to enhance their beef content of n−3 PUFA and CLA. The concentrations of CLA isomers in the different tissues were determined by GC and silver ion HPLC. The diet affected the distribution of individual CLA isomers in the lipids of the different tissues. The concentration (mg/100 g fresh tissue) of the most prominent isomer, cis-9,trans-11 18∶2, was increased up to 1.5 times in liver and heart tissue of bulls fed on pasture as compared with concentrate. However, no diet effect was observed for cis-9,trans-11 18∶2 in the lipids of longissimus muscle and subcutaneous fat. In all tissues, the second-most abundant CLA isomer in concentratefed bulls was trans-7,cis-9 18∶2. In contrast, trans-11,cis-13 18∶2 was the second-most abundant CLA isomer in all investigated tissue lipids of pasture-fed bulls. The concentration of the trans-11,cis-13 18∶2 isomer was up to 15 times higher in tissues of pasture-fed bulls as compared with concentrate-fed animals. Furthermone, diet affected the concentrations of the CLA trans,trans 18∶2 isomers. Pasture feeding significantly increased the concentrations of some trans,trans 18∶2 isomers as compared with concentrate, predominantly trans-12,trans-14 18∶2 and trans-11,trans-13 18∶2. Overall, pasture feeding resulted in significantly increased concentrations of the sum of CLA isomers in the lipids of longissimus, muscle, subcutaneous fat, heart and liver muscle of German Holstein and German Simmental bulls, but not in semitendinosus muscle.     

Extrusion deactivation of rice bran enzymes by pH modification

Rice bran is considered in Mexico as “waste”, useful only for feeds. As considerable amounts of oil are available in rice bran, it might be worthwhile to stabilize it and extract the edible oil before using it for feedstuffs. Precisely these oils are responsible for rice bran rapid deterioration, particularly in climatic conditions such as those prevalent in Mexico's tropical areas (high humidity and high temperature). This paper deals with the study of the effect of pH during extrusion of fresh rice bran in order to inactivate lipid‐breaking enzymes. Hydrochloric acid or calcium hydroxide, Ca(OH)₂, were added at 0, 1, 5, 10% (dry basis), and moisture content of the bran samples was varied (20, 30, 40%, dry basis) in a 3² factorial design to corroborate its effect at acid and alkaline pH range. Free fatty acids (FFA) increase was the control variable. Extruded samples were stored at room temperature (between 20 and 28 °C) using a non‐extruded sample as control to assess the shelf life effects. Results indicate that in acid‐extruded samples, the increase in FFA concentration after 98 days was much less than in the unmodified‐pH or alkaline samples. The lowest FFA increase after 3 months of storage time was <10 mg FFA/g rice bran using extrusion with no water or chemicals added or using extrusion adding HCl, irrespective of the moisture content of rice bran.