Comparison of Separations of Fatty Acids from Fish Products Using a 30-m Supelcowax-10 and a 100-m SP-2560 Column

Commercial fish oils and foods containing fish may contain trans and/or isomerized fatty acids (FA) produced during processing or as part of prepared foods. The current American Oil Chemists’ Society (AOCS) official method for marine oils (method Ce 1i-07) is based on separation by use of poly(ethylene glycol) (PEG) columns, for example Supelcowax-10 or equivalent, which do not resolve most unsaturated FA geometric isomers. Highly polar 100-m cyanopropyl siloxane (CPS) columns, for example SP-2560 and CP Sil 88 are recommended for separation of geometric FA isomers. Complementary separations were achieved by use of two different elution temperature programs with the same CPS column. This study is the first direct comparison of the separations achieved by use of 30-m Supelcowax-10 and 100-m SP-2560 columns for fatty acid methyl esters (FAME) prepared from the same fish oil and fish muscle sample. To simplify the identification of the FA in these fish samples, FA were fractionated on the basis of the number and type of double bonds by silver-ion solid-phase extraction (Ag⁺-SPE) before GC analysis. The results showed that a combination of the three GC separations was necessary to resolve and identify most of the unsaturated FA, FA isomers, and other components of fish products, for example phytanic and phytenic acids. Equivalent chain length (ECL) values of most FAME in fish were calculated from the separations achieved by use of both GC columns; the values obtained were shown to be consistent with previously reported values for the Supelcowax-10 column. ECL values were also calculated for the FA separated on the SP-2560 column. The calculated ECL values were equally valid under isothermal and temperature-programmed elution GC conditions, and were valuable for confirmation of the identity of several unsaturated FAME in the fish samples. When analyzing commercially prepared fish foods, deodorized marine oils, or foods fortified with marine oils it is strongly recommended that quantitative data acquired by use of PEG columns is complemented with data obtained from separations using highly polar CPS columns.     

A finite element formulation to model the flow of flotation foams

In this paper, a numerical model for the flow of foams in flotation cells in up to three dimensions is described. By using finite elements to solve Laplace's equation for a potential scalar, the flow pattern and velocity of the foam can be obtained. This has allowed, for the first time, the carrying out of numerical investigations of foam flow patterns regardless of the symmetry of the system. The numerical model has been implemented in Fluidity, a general purpose finite element method code that allows simulations to be carried out on anisotropic unstructured meshes. Such a model is of particular interest since other phenomena occurring in flotation depend on the foam velocity. Convergence tests that verify the numerical model are presented, and simulation results that showcase important features of the present implementation are discussed.     

Evaluating the In Vitro Metabolism of Docosahexaenoic Acid in Sheep Rumen Fluid

Rumen metabolism (e.g., biohydrogenation) of dietary unsaturated fatty acids (FA) is one of the main reasons why ruminant fats tend to be highly saturated and contain many isomerized FA intermediates. The process by which long-chain (20- to 24-carbon FA) polyunsaturated FA (LC-PUFA) are metabolized by rumen bacteria is not as well understood as that of linoleic or linolenic acids. In order to better understand the fate of LC-PUFA in the rumen several concentrations of docosahexaenoic acid (DHA) were evaluated in in vitro batch incubations ranging from 100 to 1,500 μg per 6 mL of incubation volume using rumen fluid from sheep and incubated for 0, 1, 2, 3, and 6 h. From the results, it was shown that DHA was extensively metabolized at low (100 to 300 μg/6 mL incubation volume), but not at high level of inclusion (800 μg). At 300 μg of DHA most of the depleted DHA was recovered as LC-DHA metabolites within the first 6 h of incubation, and at the lowest levels (100 μg of incubation volume) further metabolism is apparent at 6 h. Using SP-2560 GC columns several LC-DHA metabolites were shown to elute after 24:0 and just past DHA, a region generally free of interfering FA. The present in vitro study would appear to be a useful method to evaluate the production of DHA metabolites in combination with its depletion.     

Application of inline imaging for monitoring crystallization process in a continuous oscillatory baffled crystallizer

In this study, an in situ imaging system has been analysed to characterize the crystal size, the shape and the number of particles during a continuous crystallization process in a Continuous Oscillatory Baffled Crystallizer (COBC). Two image analysis approaches were examined for particle characterization in the suspension containing both small nuclei and larger grown crystals (nonspherical and irregular in shape). The pattern matching approach, in which the particles are approximated to be spherical, did result in an overestimation of the size. Alternatively, a segmentation‐based algorithm resulted in reliable crystal size and shape characteristics. The laser diffraction analysis in comparison to the image analysis overestimated the particle sizes due to the agglomeration of particles upon filtration and drying. The trend in the particle counts during the start of crystallization process, including nucleation, determined by the image analysis probe was comparable with the one measured by FBRM, highlighting the potential of in situ imaging for process monitoring. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2450–2461, 2018     

Dielectric relaxation of polar aromatics in unoriented and oriented linear low‐density polyethylene

The dielectric behavior of some polar aromatics dissolved in nonpolar unoriented and stretched linear low‐density polyethylene was investigated within the temperature region between 150 and 350 K. The measurements were carried out in the frequency range 1 kHz to 10 MHz. The maximum temperatures and the half widths of the loss tangent peaks depend upon the shape and the polar structure of guest molecules. Stretching the samples induced a shift of the loss tangent to higher temperatures, decreased the height, and increased the width of tan δ peak. The activation energy is also influenced by the type of guest molecules and orientation of polymer matrix. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1278–1282, 2001     

First Application of Newly Developed FT-NIR Spectroscopic Methodology to Predict Authenticity of Extra Virgin Olive Oil Retail Products in the USA

Economically motivated adulteration (EMA) of extra virgin olive oils (EVOO) has been a worldwide problem and a concern for government regulators for a long time. The US Food and Drug Administration (FDA) is mandated to protect the US public against intentional adulteration of foods and has jurisdiction over deceptive label declarations. To detect EMA of olive oil and address food safety vulnerabilities, we used a previously developed rapid screening methodology to authenticate EVOO. For the first time, a recently developed FT-NIR spectroscopic methodology in conjunction with partial least squares analysis was applied to commercial products labeled EVOO purchased in College Park, MD, USA to rapidly predict whether they are authentic, potentially mixed with refined olive oil (RO) or other vegetable oil(s), or are of lower quality. Of the 88 commercial products labeled EVOO that were assessed according to published specified ranges, 33 (37.5%) satisfied the three published FT-NIR requirements identified for authentic EVOO products which included the purity test. This test was based on limits established for the contents of three potential adulterants, oils high in linoleic acid (OH-LNA), oils high in oleic acid (OH-OLA), palm olein (PO), and/or RO. The remaining 55 samples (62.5%) did not meet one or more of the criteria established for authentic EVOO. The breakdown of the 55 products was EVOO potentially mixed with OH-LNA (25.5%), OH-OLA (10.9%), PO (5.4%), RO (25.5%), or a combination of any of these four (32.7%). If assessments had been based strictly on whether the fatty acid composition was within the established ranges set by the International Olive Council (IOC), less than 10% would have been identified as non-EVOO. These findings are significant not only because they were consistent with previously published data based on the results of two sensory panels that were accredited by IOC but more importantly each measurement/analysis was accomplished in less than 5 min.     

Ewma charts for multivariate time series

In this paper a muIt,ivariat.e EWMA chart for time series is introduced. In principle, it is a generalization of the control scheme of Lowry et al. (I992) for multivarite indendent observations.

The autocovariances of the EWMA recursion are derived for stationary multivariate time series. IYsing tllese reslllts a co11t.rol chart hased or1 t11 illt.ivariate EWMA recursion is proposed. For a multivariate autoregressive process of order 1, a sufficient. condition is given such that the in-control average run length (ARL) is invariant, withrespect to the covariance of the White Noise process. This scheme is compared with the MEWMA control chart of Lowry et al. (1992) applied to the residuals.

By an extensive Monte carlo study the ARL of both charts are determined for several multivariate autoregressive processses.     

Fabrication and characterization of planar and channel polymer waveguides. III. Compositional distribution and solute loss in polymer thin films

For many microelectronic and optoelectronic applications, polymer thin films require the addition of small molecules. However, the thin‐film geometry and associated processing techniques will influence the final morphology and compositional distribution of the constituents. It is therefore important that these be examined directly rather than inferred from bulk measurements. As an example system, the concentration and distribution of Disperse Red 1 (DR1) molecules in poly(methyl methacrylate) thin films were examined. Ultraviolet visibility spectroscopy and dynamic secondary ion mass spectrometry indicate that the composition of the molecules decreased dramatically with thermal treatment of the film. The sublimation of the chromophore was observed to occur at temperatures well below the melting point of the small molecule and the glass transition of the pure polymer; this solute loss manifested itself in changes in the glass transition temperature of the film. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2021–2024, 2002