ELISA kit for peanut protein determination: collaborative study.

A collaborative study in 10 laboratories was performed to validate an ELISA method developed for the quantitative determination of peanut protein in foods. The ELISA kit used for this study is based on rabbit polyclonal antibody. This kit does not produce any false-positive results or cross-reactivity with a broad range of peanut-free food matrixes. All participants obtained the peanut ELISA kit with standard operational procedures, a list of samples, the samples, and a protocol for recording test results. The study included 15 food samples. Three food matrix samples of zero peanut content showed peanut protein content lower than the first standard (0.10 mg/kg). Three samples with peanut declared as an ingredient revealed peanut protein content outside the calibration curve (absorbance was above the highest standard) in all laboratories, and three samples had the peanut content reported either above the highest standard or within the calibration curve, depending on the laboratory. Six samples with peanut declared as an ingredient gave the peanut protein content within the calibration curve. Only these six samples, together with a positive control sample (CS2), were used for statistical evaluation. The statistical tests (Cochran, Grubbs, and Mandel) and analysis of variance were used for the evaluation of the collaborative study results. Repeatability and reproducibility limits, as well as an LOQ (LOQcollaborative 0.22 mg peanut proteins/kg) and an LOD (LODcollaborative 0.07 mg peanut proteinslkg) for the kit were calculated.

Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography/mass spectrometry and gas chromatography/flame ionization detection.

Fatty acid (FA) and triacylglycerol (TG) composition of natural oils and fats intake in the diet has a strong influence on the human health and chronic diseases. In this work, non-aqueous reversed-phase (NARP) and silver-ion high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection and gas chromatography with flame-ionization detection (GC/FID) and mass spectrometry detection are used for the characterization of FA and TG composition in complex samples of animal fats from fallow deer, red deer, sheep, moufflon, wild boar, cock, duck and rabbit. The FA composition of samples is determined based on the GC/FID analysis of FA methyl esters. In total, 81 FAs of different acyl chain length, double bond (DB) number, branched/linear, cis-/trans- and DB positional isomers are identified. TGs in animal fats contain mainly monounsaturated and saturated FAs. High amounts of branched and trans-FAs are observed in the samples of ruminants. In NARP mode, individual TG species are separated including the separation of trans- and branched TGs. Silver-ion mode provides the separation of TG regioisomers, which enables the determination of their ratios. Great differences in the preference of unsaturated and saturated FAs in the sn-2 position on the glycerol skeleton are observed among individual animal fats. Unsaturated FAs are preferentially occupied in the sn-2 position in all animal samples except for wild boar with the strong preference of saturated FAs in the sn-2 position.