111 research outputs found
Discrimination among geometrical isomers of α-linolenic acid methyl ester using low energy electron ionization mass spectrometry
Current Analytical Techniques for Food Lipids
Thee analysis of food lipids presents significant challenges due to the wide variety of sample matrices, large range of total fat contents, and complex compositions of fatty acids. This is chapter reviews conventional analytical techniques for the quantification of total fat and fatty acids in foods and food ingredients, including the gravimetric determination of total fat, the calculation of fat and fatty acids using gas chromatography (GC), and the analysis of proximates content (i.e., fat, protein, carbohydrate, moisture, and ash) by Fourier transform infrared (FTIR) spectroscopy. Current official methods of analysis are evaluated and the use of certified reference materials and spike-recovery experiments for verifying method performance is discussed. Recent advances in automated and semi-automated sample preparation systems and rapid and portable spectroscopic devices are highlighted for their potential to significantly improve the speed by which accurate determinations of total fat and fatty acids may be achieved
Matrix Extension Validation of AOCS Ce 2câ11 for Omegaâ3 Polyunsaturated Fatty Acids in Conventional Foods and Dietary Supplements Containing Added Marine Oil
Gas chromatographic/matrix isolation/Fourier transform infrared spectroscopic determination of trans-monounsaturated and saturated fatty acid methyl esters in partially hydrogenated menhaden oil
Accelerating Bacterial Identification by Infrared Spectroscopy by Employing Microarray Deposition of Microorganisms
ABSTRACT A microarray method for the deposition of bacteria onto an agar slide was developed to accelerate the formation of microcolonies. Representative microarrays each consisting of 40 micro-spots of five replicates of eight foodborne bacteria (Yersinia enterocolitica, Staphylococcus aureus, Salmonella typhimurium, Listeria monocytogenes, Enterobacter cloacae, Citrobacter freundii, Klebsiella pneumoniae, and Escherichia coli) were printed on a Brain Heart Infusion (BHI) agar slide using a contact micro-spotting robotic system. Within 3 h, sufficient bacterial cells were obtained to allow accurate identification of the microorganism by infrared spectroscopy. This approach allows a "complete-in-a-single-day" analysis of a large array of samples. 17
Rapid Turbidimetric Detection of Milk Powder Adulteration with Plant Proteins
Development
of assays to screen milk for economically motivated adulteration with
foreign proteins has been stalled since 2008 due to strong international
reactions to the melamine poisoning incident in China and the surveillance
emphasis placed on low molecular weight nitrogen-rich adulterants.
New screening assays are still needed to detect high molecular weight
foreign protein adulterants and characterize this understudied potential
risk. A rapid turbidimetric method was developed to screen milk powder
for adulteration with insoluble plant proteins. Milk powder samples
spiked with 0.03â3% by weight of soy, pea, rice, and wheat
protein isolates were extracted in 96-well plates, and resuspended
pellet solution absorbance was measured. Limits of detection ranged
from 100 to 200 ÎŒg, or 0.1â0.2% of the sample weight,
and adulterant pellets were visually apparent even at âŒ0.1%.
Extraction recoveries ranged from 25 to 100%. Assay sensitivity and
simplicity indicate that it would be ideally suitable to rapidly screen
milk samples in resource poor environments where adulteration with
plant protein is suspected
Application of standard addition to eliminate conjugated linoleic acid and other interferences in the determination of total Trans
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