Mark Bücking

Development of a Candidate Reference Method for the Simultaneous Quantitation of the Boar Taint Compounds Androstenone, 3α-Androstenol, 3β-Androstenol, Skatole, and Indole in Pig Fat by Means of Stable Isotope Dilution Analysis–Headspace Solid-Phase Microextraction–Gas Chromatography/Mass Spectrometry

The steroidal pig pheromones androstenone (5α-androst-16-en-3-one), 3α-androstenol (5α-androst-16-en-3α-ol), and 3β-androstenol (5α-androst-16-en-3β-ol) as well as the heterocyclic aromatic amines skatole and indole, originating from microbial degradation of tryptophan in the intestine of pigs, are frequently recognized as the major compounds responsible for boar taint. A new procedure, applying stable isotope dilution analysis (SIDA) and headspace solid-phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS) for the simultaneous quantitation of these boar taint compounds in pig fat was developed and validated. The deuterated compounds androstenone-d(3), 3β-androstenol-d(3), skatole-d(3), and indole-d(6) were synthesized and successfully employed as internal standards for SIDA. The new procedure is characterized by a fast, simple, and economic sample preparation: methanolic extraction of the melted fat followed by a freezing and an evaporation step allows for extraction and enrichment of all five analytes. Additional time-consuming cleanup steps were not necessary, as HS-SPME sampling overcomes fat-associated injector and column contamination. The method has been validated by determining intra- and interday precision and accuracy as well as the limit of detection (LOD) and limit of quantitation (LOQ). Additionally, a cross-validation for androstenone, skatole, and indole was carried out comparing the results of 25 back fat samples obtained simultaneously by the new SIDA-HS-SPME-GC/MS procedure with those obtained in separate GC/MS and high-performance liquid chromatography fluorescence detection (HPLC-FD) measurements. The cross-validation revealed comparable results and confirms the feasibility of the new SIDA-HS-SPME-GC/MS procedure.

Different scalding techniques do not affect boar taint.

The prevention of unpleasant boar taint is the main reason for castration of male piglets. For animal welfare reasons, castration is announced to be banned in the European Community. This study aimed to investigate whether androstenone, skatole and indole in backfat of boars may be reduced by different scalding technologies. To discriminate ante and post mortem effects, carcasses were sampled before and after scalding in two abattoirs using either horizontal (TANK) or vertical (TUNNEL) scalding. Backfat samples were analysed using gas chromatography (androstenone) and liquid chromatography (skatole, indole). Neither TANK nor TUNNEL scalding did significantly reduce malodorous compounds. Skatole and androstenone in backfat obtained after scalding averaged 112 ± 123 ng/g and 1196 ± 885 ng/g melted fat, respectively; significant differences between abattoirs were observed for skatole. Increased skatole levels were tentatively assigned to longer transport duration. Concluding from recent consumer research and subsequent application of suggested sensory rejection thresholds for androstenone (2000 ng/g) and skatole (150 ng/g), nearly 30% of the carcasses may be unacceptably tainted.

Detection of coffee flavour ageing by solid-phase microextraction/surface acoustic wave sensor array technique (SPME/SAW)

The use of polymer coated surface acoustic wave (SAW) sensor arrays is a very promising technique for highly sensitive and selective detection of volatile organic compounds (VOCs). We present new developments to achieve a low cost sensor setup with a sampling method enabling the highly reproducible detection of volatiles even in the ppb range. Since the VOCs of coffee are well known by gas chromatography (GC) research studies, the new sensor array was tested for an easy assessable objective: coffee ageing during storage. As reference method these changes were traced with a standard GC/FID set-up, accompanied by sensory panellists. The evaluation of GC data showed a non-linear characteristic for single compound concentrations as well as for total peak area values, disabling prediction of the coffee age. In contrast, the new SAW sensor array demonstrates a linear dependency, i.e. being capable to show a dependency between volatile concentration and storage time.

Low-cost gas chromatography with gas sensor array for rapid tests in food industry processes

A portable low-cost gas chromatographic measurement system will be presented. The system consists of a novel chromatographic column - which enables measurements at room temperature and ambient air - with a downstream micro machined gas sensor array and offers the separation and identification of volatile organic compounds. The targeted application is the monitoring of flavours directly during food processing. The measurement system was characterized by using flavours like methyl pyrrole, hexanal, pinene, ethyl butyrate and limonene as test gases. Reliable and reproducible identification of the gases in the concentration range of a few ppb has been achieved.

Four Chemical Trends Will Shape the Next Decade's Directions in Perfluoroalkyl and Polyfluoroalkyl Substances Research

Per- and polyfluoroalkyl substances (PFAS) represent a versatile group of ubiquitously occurring chemicals of increasing regulatory concern. The past years lead to an ever expanding portfolio of detected anthropogenic PFAS in numerous products encountered in daily life. Yet no clear picture of the full range of individual substance that comprise PFAS is available and this challenges analytical and engineering sciences. Authorities struggle to cope with uncertainties in managing risk of harm posed by PFAS. This is a result of an incomplete understanding of the range of compounds that they comprise in differing products. There are analytical uncertainties identifying PFAS and estimating the concentrations of the total PFAS load individual molecules remain unknown. There are four major trends from the chemical perspective that will shape PFAS research for the next decade. Mobility: A wide and dynamic distribution of short chain PFAS due to their high polarity, persistency and volatility. Substitution of regulated substances: The ban or restrictions of individual molecules will lead to a replacement with substitutes of similar concern. Increase in structural diversity of existing PFAS molecules: Introduction of e.g., hydrogens and chlorine atoms instead of fluorine, as well as branching and cross-linking lead to a high versatility of unknown target molecules. Unknown “Dark Matter”: The amount, identity, formation pathways, and transformation dynamics of polymers and PFAS precursors are largely unknown. These directions require optimized analytical setups, especially multi-methods, and semi-specific tools to determine PFAS-sum parameters in any relevant matrix.

Characterization of Selected Organic and Mineral Components of Qvevri Wines

The organic and mineral components of 20 qvevri wines from selected wineries throughout Europe were evaluated to gain insight into one of the oldest known methods of wine production. The pH, residual glucose, titratable acidity, specific organic acids (acetic, lactic, malic, and tartaric acids), phenolics (total phenolics and anthocyanins in red wines), total antioxidants, and selected minerals (phosphorus, calcium, magnesium, manganese, potassium and zinc) of the samples were measured. The data were compared with previously reported values for conventional wines. Qvevri wines were less acidic than conventional wines, containing higher levels of acetic and lactic acids but lower levels of tartaric acid. They also contained higher levels of antioxidants and total phenolics, the latter up to 10 times more abundant in the white wine varieties than in conventional wines. Despite fermentation in clay vessels, the mineral content of qvevri wines was within the normal reported range, although phosphorus levels were slightly higher. This is the only study that has considered the compositional nature of qvevri wines.

Miniaturised gas chromatographic system with metal oxide gas sensor array for fast detection of off-flavors

A portable low-cost gas chromatographic measurement system with a micro machined gas sensor array as detector unit is presented. The system offers the separation and identification of volatile organic compounds and enables on-line monitoring of processes in food industry. This includes food quality, e.g. in fruit stores, slaughterhouse and for consumer protection. Further applications are the detection of off-flavors in meat from non-castrated male pigs and microbiological contaminations. Reliable and reproducible identification of aromatic compounds in the concentration range of a few ppb has been achieved.