Effect of preparation conditions on release of selected volatiles in tea headspace

The release of volatile compounds from infused tea was monitored using on-line atmospheric pressure chemical ionization (APCI) mass spectrometry. Assignment of the APCI ions to particular compounds was achieved using gas chromatography of tea headspace with dual electron ionization and APCI-MS detectors. Six ions in the APCI spectrum could be assigned to individual compounds, five ions were associated with isobaric compounds (e.g., 2- and 3-methylbutanal and pentanal) or stereoisomers (e.g., heptenals or heptadienals), and a further four ions monitored were identified compounds but with some unknown impurities. Reproducibility of infusion preparation and the analytical system was good with percentage variation values generally below 5%. The analysis was used to study the effect of infusion and holding temperatures on the volatile profile of tea headspace samples, and this was found to be compound-dependent. Both the extraction of volatiles from leaf tea and the release of volatiles into the headspace play a role in creating the aroma profile that the consumer experiences.     

Identification and monitoring of intermediates and products in the acrylamide pathway using online analysis

Acrylamide formation under controlled processing conditions was studied in a starch matrix by analyzing volatile compounds in the gas phase using online mass spectrometry. Compounds were identified using mass spectral analysis, authentic standards, and the labeling patterns from isotopically labeled asparagine and sugars. Acrylamide, 3-aminopropanamide, methylpyrazine, 3-oxopropanamide, and aminopropan-2-one were assigned to the ions at m/ z 72, 89, 95, 88, and 74, respectively. Ion m/ z 60 was proposed as the transamination product of glyoxal, but labeling experiments did not support this assignment. Temporal formation of acrylamide and related compounds was studied in 51 samples containing asparagine and selected sugars or carbonyls. Data from the experiments were analyzed to investigate correlations between the amounts of acrylamide, intermediates, and pyrazines formed. A strong correlation between 3-aminopropanamide and acrylamide was found in all samples, whereas other correlations were reactant specific. Preliminary multiway analysis of the data identified temporal similarities in the ion profiles and showed that dynamic monitoring can follow the production and utilization of intermediates leading to acrylamide.     

Records of Bursaphelenchus spp. (Nematoda,Parasitaphelenchidae) in coniferous timber imported from the Asian part of Russia

Coniferous wood imported from the Asian part of Russia was surveyed in Germany (Mukran ferry terminal, highway and railway border station in Frankfurt/Oder) and Austria (railway in Marchegg, Retz and Wr. Neustadt, Lower Austria). The consignments consisted of mixed timber of Pinus/Picea or Pinus/Larix. Out of 625 samples investigated, 51 samples (8.5%) yielded eight Bursaphelenchus species. Bursaphelenchus mucronatus was found 42 times in Pinus, Picea and Larix wood, Bursaphelenchus hylobianum and Bursaphelenchus fraudulentus were detected twice, in Pinus/Larix and in Larix, respectively. The following species were each found once: Bursaphelenchus leoni in mixed timber of Pinus/Picea, Bursaphelenchus ‘borealis’ in Pinus, Bursaphelenchus hellenicus and Bursaphelenchus paracorneolus in Larix. One sample of Larix wood from Krasnoyarsk region contained a few specimens corresponding to Bursaphelenchus xylophilus. Bursaphelenchus mucronatus was present in about 30% of the samples showing signs of insect attack. A Monochamus species was found in a sample from Irkutsk. Most of the B. mucronatus isolates found belonged to the European genotype, whereas the East Asian genotype was found in three instances. This is the first report of B. fraudulentus, B. hellenicus, B. leoni, B. paracorneolus and the East Asian genotype of B. mucronatus in Russia. Bursaphelenchus hylobianum is the only species found in Russian wood and not in Europe so far. The species were identified morphologically and by internal transcribed spacer (ITS)‐restriction fragment length polymorphism (RFLP) technique. Species‐specific ITS‐RFLP patterns were established for B. hylobianum. In the case of the isolate morphologically corresponding to B. xylophilus, DNA extraction from the available low number of specimens failed to yield sufficient rDNA for ITS‐RFLP analysis.