Determination of total nitrogen content, pH, density, refractive index, and brix in Thai fish sauces and their classification by near-infrared spectroscopy with searching combination moving window partial least squares

Near-infrared (NIR) transflectance spectra in the region of 1100-2500 nm were measured for 100 Thai fish sauces. Quantitative analyses of total nitrogen (TN) content, pH, refractive index, density and brix in the Thai fish sauces and their qualitative analyses were carried out by multivariate analyses with the aid of wavelength interval selection method named searching combination moving window partial least squares (SCMWPLS). The optimized informative region for TN selected by SCMWPLS was the region of 2264-2428 nm. A PLS calibration model, which used this region, yielded the lowest root mean square error of prediction (RMSEP) of 0.100% w/v for the PLS factor of 5. This prediction result is significantly better than those obtained by using the whole spectral region or informative regions selected by moving window partial least squares regression (MWPLSR). As for pH, density, refractive index and brix, the 1698-1722, and 2222-2258 nm regions, the 1358-1438 nm region, the 1774-1846, and 2078-2114 nm regions, and the 1322-1442, and 2000-2076 nm regions were selected by SCMWPLS as the optimized regions. The best prediction results were always obtained by use of the optimized regions selected by SCMWPLS. The lowest RMSEP for pH, density, refractive index and brix were 0.170, 0.007 g cm(-3), 0.0079 and 0.435 degrees Brix, respectively. Qualitative models were developed by using four supervised pattern recognitions, linear discriminant analysis (LDA), factor analysis-linear discriminant analysis (FA-LDA), soft independent modeling of class analog (SIMCA), and K neareat neighbors (KNN) for the optimized combination of informative regions of the NIR spectra of fish sauces to classify fish sauces into three groups based on TN. All the developed models can potentially classify the fish sauces with the correct classification rate of more than 82%, and the KNN classified model has the highest correct classification rate (95%). The present study has demonstrated that NIR spectroscopy combined with SCMWPLS is powerful for both the quantitative and qualitative analyses of Thai fish sauces.     

Feasibility of near-infrared spectroscopy to detect and to quantify adulterants in cow milk.

Cow milk adulteration involves the dilution of milk with a less-expensive component, such as water or whey. Near-infrared spectroscopy (NIRS) was employed to detect the adulterations of milk, non-destructively. Two adulteration types of cow milk with water and whey were prepared, respectively. NIR spectra of milk adulterations and natural milk samples in the region of 1100 - 2500 nm were collected. The classification of milk adulterations and natural milk were conducted by using discriminant partial least squares (DPLS) and soft independent modelling of class analogy (SIMCA) methods. PLS calibration models for the determination of water and whey contents in milk adulteration were also developed, individually. Comparisons of the classification methods, wavelength regions and data pretreatments were investigated, and are reported in this study. This study showed that NIR spectroscopy can be used to detect water or whey adulterants and their contents in milk samples.     

Depolymerization and ionic conductivity of enzymatically deproteinized natural rubber having epoxy group

Preparation of liquid epoxidized natural rubber (ENR) was made by oxidative depolymerization of ENR in latex stage without loss of epoxy group. Epoxidation of fresh natural rubber latex, which was purified by deproteinization with proteolytic enzyme and surfactant, was carried out with freshly prepared peracetic acid. The glass transition temperature (T_g) and gel content of the rubbers increased after the epoxidation, both of which were dependent upon an amount of peracetic acid. The gel content was significantly reduced by oxidative depolymerization of the rubber with (NH₄)₂S₂O₈ in the presence of propanal. The resulting liquid epoxidized rubber (M_n≈10⁴) was found to have well-defined terminal groups, i.e. aldehyde groups and α-β unsaturated carbonyl groups. The novel rubber was applied to transport Li⁺ as an ionic conducting medium, that is, solid polymer electrolyte.     

Interaction of cubosomes with plasma components resulting in the destabilization of cubosomes in plasma

Cubosomes are novel dispersed nanoparticles with bicontinuous cubic phases of monoolein in their interior. We investigated their disintegration process in plasma by in vitro and in vivo studies. Cubosomes were incubated with whole plasma or plasma components such as HDL, LDL, and albumin. The lypolysis study indicated lipolytic activity of whole plasma towards cubosomes. Gel filtration chromatography revealed that HDL, LDL and albumin interacted with cubosomes. HDL affected cubosomes’ integrity and gave rise to smaller particles which contained the components of both cubosomes and HDL. Upon incubation with LDL, cubosomes fused with LDL. Albumin was shown to take up monoolein out of the particles. Cubosomes were disintegrated by whole plasma as a result of the interaction with plasma components. It was concluded that in vivo observation of a long circulation time of a hydrophobic substance in cubosomes was due to the sustained behavior of cubosome remnant particles.     

Removal of proteins from natural rubber with urea

Removal of proteins from natural rubber was achieved by incubation of the rubber latex with urea in the presence of a surfactant to prevent the latex‐allergy caused with thin film products. Temperature, pH and time for the incubation were investigated to remove the proteins effectively, in which nitrogen content of the rubber was reduced to 0.02 from 0.38 wt% under the optimum condition. To remove further the proteins, deproteinization of natural rubber was made by incubation of the latex with proteolytic enzyme in the presence of a surfactant followed by incubation with urea. Amount of allergen decreased through the procedure to less than 0.7 μg/ml, which is a small amount of allergen compared to that for the commercial, deproteinized natural rubber. Copyright © 2004 John Wiley & Sons, Ltd.     

Latex‐state NMR spectroscopy for quantitative analysis of epoxidized deproteinized natural rubber

Method of quantitative analysis through latex‐state ¹³C NMR spectroscopy was established for in situ determination of epoxy group content of epoxidized natural rubber in latex stage. The epoxidized natural rubber latex was prepared by epoxidation of deproteinized natural rubber with freshly prepared peracetic acid in latex stage. The resulting epoxidized deproteinized natural rubber (EDPNR) latex was characterized through latex‐state ¹³C NMR spectroscopy. Chemical shift values of signals of latex‐state ¹³C NMR spectrum for EDPNR were similar to those of solution‐state ¹³C NMR spectrum for EDPNR. Resolution of latex‐state ¹³C NMR spectrum was gradually improved as temperature for the nuclear magnetic resonance (NMR) measurement increased to 70°C. Signal‐to‐noise ratio of latex‐state ¹³C NMR measurement was similar to that of solution‐state ¹³C NMR measurement at temperature above 50°C. The epoxy group content determined through latex‐state NMR spectroscopy was proved to be the same as that determined through solution‐state NMR spectroscopy. Copyright © 2017 John Wiley & Sons, Ltd.     

Gallium Oxide Nanorods: Novel,Template‐Free Synthesis and High Catalytic Activity in Epoxidation Reactions

Gallium oxide nanorods with unprecedented small dimensions (20–80 nm length and 3–5 nm width) were prepared using a novel, template‐free synthesis method. This nanomaterial is an excellent heterogeneous catalyst for the sustainable epoxidation of alkenes with H₂O₂, rivaling the industrial benchmark microporous titanosilicate TS‐1 with linear alkenes and being much superior with bulkier substrates. A thorough characterization study elucidated the correlation between the physicochemical properties of the gallium oxide nanorods and their catalytic performance, and underlined the importance of the nanorod morphology for generating a material with high specific surface area and a high number of accessible acid sites.     

Growth Inhibition of Thermotolerant Yeast,Kluyveromyces marxianus,in Hydrolysates from Cassava Pulp

In this study, we report the inhibition of Kluyveromyces marxianus TISTR5925 growth and ethanol fermentation in the presence of furan derivatives and weak acids (acetic acid and lactic acid) at high temperatures. Cassava pulp, obtained as the waste from starch processing, was collected from 14 starch factories located in several provinces of Thailand. At a high temperature (42 °C), the cassava pulp hydrolysate from some starch factories strongly inhibited growth and ethanol production of both K. marxianus (strain TISTR5925) and Saccharomyces cerevisiae (strain K3). HPLC detected high levels of lactic acid and acetic acid in the hydrolysates, suggesting that these weak acids impaired the growth of K. marxianus at high temperature. We isolated Trp-requiring mutants that had reduced tolerance to acetic acid compared to the wild-type. This sensitivity to acetic acid was suppressed by supplementation of the medium with tryptophan.     

Transition-metal-free catalysts for the sustainable epoxidation of alkenes: from discovery to optimisation by means of high throughput experimentation

Transition-metal-free oxides were studied as heterogeneous catalysts for the sustainable epoxidation of alkenes with aqueous H?O? by means of high throughput experimentation (HTE) techniques. A full-factorial HTE approach was applied in the various stages of the development of the catalysts: the synthesis of the materials, their screening as heterogeneous catalysts in liquid-phase epoxidation and the optimisation of the reaction conditions. Initially, the chemical composition of transition-metal-free oxides was screened, leading to the discovery of gallium oxide as a novel, active and selective epoxidation catalyst. On the basis of these results, the research line was continued with the study of structured porous aluminosilicates, gallosilicates and silica-gallia composites. In general, the gallium-based materials showed the best catalytic performances. This family of materials represents a promising class of heterogeneous catalysts for the sustainable epoxidation of alkenes and offers a valid alternative to the transition-metal heterogeneous catalysts commonly used in epoxidation. High throughput experimentation played an important role in promoting the development of these catalytic systems.