Volatile organic compounds in preen oil and feathers - a review.

For a long time birds were assumed to be anosmic or at best microsmatic, with olfaction a poorly understood and seldom investigated part of avian physiology. The full viability of avian olfaction was first discovered through its functions in navigation and foraging. Subsequently, researchers have investigated the role of olfaction in different social and non-social contexts, including reproduction, kin recognition, predator avoidance, navigation and foraging. In parallel to the recognition of the importance of olfaction for avian social behaviour, there have been advances in the techniques and methods available for the sampling and analysis of trace volatiles and odourants, leading to insights into the chemistry underlying chemical communication in birds. This review provides (i) an overview of the current state of knowledge regarding the volatile chemical composition of preen oil and feathers, its phylogenetic coverage, chemical signatures and their potential functions, and (ii) a discussion of current methods used for the isolation and detection of volatiles. Finally, lines for future research are proposed.

Recovery rates of selected body odor substances in different textiles applying various work-up and storage conditions measured by gas chromatography-mass spectrometry.

BACKGROUND: Body odor is an important aspect in interpersonal communication. For psychological and chemical research on body odors, suitable procedures for sampling and application, and analysis of body odors are essential. In this study, different textile fabrics (polyester, cotton, and Gazin gauze) were comparatively evaluated in view of their potential suitability for body odor sampling by determining recovery rates of selected body odor substances. In addition, the impact of sample preparation and storage conditions on the recovery rates was determined. RESULTS: The recovery rates of dimethyl disulfide, (E)-non-2-enal, 5α-androst-16-en-3-one, 6-methylhept-5-en-2-one, heptanal and 3-sulfanylhexan-1-ol were determined under different conditions of storage (storage for 30 min at room temperature or storage for 30 min at room temperature followed by freezing at - 80 °C for 4 weeks) and sample work-up (solvent extraction with and without solvent-assisted flavour evaporation, in the following: SAFE). SAFE led to overall lower recovery rates with a significant effect for (E)-non-2-enal and 5α-androst-16-en-3-one. Nevertheless, the results showed that SAFE can be an essential step when working with a complex matrix. When comparing the different fabrics, except for (E)-non-2-enal no difference between the recovery rates obtained for cotton and polyester became evident. Gazin gauze showed lower recovery rates for all compounds. Finally, our results showed that the here investigated target compounds are stable during storage for four weeks at - 80 °C. SIGNIFICANCE AND NOVELTY: The results show on the one hand that the here investigated compounds were stable during storage and that the fiber type had limited influence on overall recovery rates. On the other hand, they highlight the limitations of using textile materials for sampling of volatile substances, especially with regard to low recovery rates for certain substances and the necessity of material pre-treatment or distillation steps for enabling GC-MS analysis after solvent extraction.

Identification of odorants in wood of Calocedrus decurrens (Torr.) Florin by aroma extract dilution analysis and two-dimensional gas chromatography-mass spectrometry/olfactometry.

General emissions of volatile organic compounds from wood are well investigated, but only limited information is available on the odor-active substances contained therein. To close this gap, we aimed at specifically elucidating the odorous constituents of wood from incense cedar [Calocedrus decurrens (Torr.) Florin]; this material is commonly used for the production of a range of products such as pencils and interior accessories. Targeted odorant analysis requires specialized techniques combining modern odorant analytical tools with human-sensory evaluation. Following this concept, the odor profile of the wood sample was first evaluated by human-sensory analyses. Then, the most potent wood odorants were characterized by means of gas chromatography-olfactometry and ranked according to their odor potency via aroma extract dilution analysis. With use of this approach, more than 60 odorous substances were detected, and the 22 most potent odorants were successfully identified by gas chromatography-mass spectrometry/olfactometry and two-dimensional gas chromatography-mass spectrometry/olfactometry. Among the main odorants found were a series of terpenes, several degradation products of fatty acids, and a number of odorants with a phenolic core moiety. Five odorants are reported here for the first time as wood odorants, such as γ-octalactone and 3-phenylpropanoic acid; thymoquinone was demonstrated for the first time to have a pencil-like odor quality.

Recovery and characterisation of coloured phenolic preparations from apple seeds.

The aim of this study was to investigate whether complexly constituted phenolic extracts from apple seeds may be utilised for the recovery of natural coloured antioxidant preparations, which might serve as potential food or cosmetic ingredients. In a first step, the recovery of phenolic compounds was optimised by varying crucial extraction parameters. A single extraction step at 25°C using an acetone-water mixture (60:40, v/v) and a solid-to-solvent ratio of 1:8 (w/v) for 1 h was found to be appropriate to achieve both high phenolic yields and antioxidant activities. In a second step, differently produced apple seed extracts and a phloridzin model solution were enzymatically treated by mushroom polyphenol oxidase to investigate the rate of pigment synthesis. Depending on the extraction procedure applied, synthesis rates, pigment yields and colour properties significantly differed. Compared to the phloridzin model solution, extracts recovered from the seeds showed comparable and even better results, thus indicating such preparations to be a promising alternative to synthetic yellow dyes.