Characteristics Of Volatile Compounds Research Articles

Characterization of the aroma in barley leaves from different cultivars and tillering stages by HS-SPME/GC-MS, GC-O and E-nose

Barley leaf, as a food source with medicinal attributes, is an excellent raw material for functional food. Aroma-active compounds that characterize the unique flavor of the barely leaf is an important issue that should be clarified. Therefore, gas chromatography-mass spectrometry (GC-MS) combined with GC-olfactometry (GC-O) were employed to investigate the volatiles in barely leaves from 7 cultivars and 2 tillering stages. According to a quantitative study and odor activity value (OAV), 18 volatile compounds were identified as aroma-active components. Aldehydes and alcohols are the dominant compounds. Hexanal, 2-hexenal, and isovaleraldehyde are the most abundant compounds in the former. (E)-3-hexen-1-ol, hexanol, 1-pentene-3-ol, (E)-2-hexenol, linalool and (Z)-2-pentenol are the main aromatic active compounds in the latter. The impact of the tillering stage was more significant than that of cultivars on the characteristics of volatile compounds. Furthermore, through the multivariate statistical analysis, it was found that 9 volatile compounds with Variable Importance in Projection (VIP)≥1, including (E)-2-hexenol, (E)-3-hexene-1-ol, (Z)-2-pentenol, 2-octanone, pentadecanal, 1-penten-3-ol, linalool, 2-hexenal and hexanol, played a significant role in differentiating samples. Consistent results were also got from the quantitative descriptive analysis (QDA) and electronic nose (E-nose) measurement. Overall, it is suggested that Flower 30 and Morex are the most suitable specialized cultivars to produce barley leaf products.

Characterization of Olive Oil Volatile Compounds after Elution through Selected Bleaching Materials-Gas Chromatography-Mass Spectrometry Analysis.

Using different bleaching materials to eliminate or reduce organic volatiles in deteriorated olive oils will positively affect its characteristics. This study aims to identify the volatiles of oxidized olive oil after physical bleaching using selected immobilized adsorbents. Oxidized olive oil was eluted using open-column chromatography packed with silica gel, bentonite, resin, Arabic gum, and charcoal at a 1:5 eluent system (w/v, adsorbent: oxidized olive oil). The smoke point was determined. The collected distilled vapor was injected into GC-MS to identify the volatiles eluted after partial refining with each of these bleaching compounds. The results showed that volatile compounds were quantitatively and qualitatively affected by the type of adsorbents used for the elution of olive oil and the smoking points of eluted oils. The most prominent detected volatile compounds were limonene (14.53%), piperitone (10.35%), isopropyl-5-methyl-(2E)-hexenal (8.6%), methyl octadecenoate (6.57%), and citronellyl acetate (5.87%). Both bentonite and resin were superior in decreasing the ratio of volatile compounds compared with other bleaching materials used. Resin immobilized medium was significantly affected (p < 0.05), raising the smoke point. These results highlighted some information regarding the characteristics of volatile compounds that result after the physical elution of olive oil through selected adsorbents.

Characteristics of Volatile Compounds and Sensory Properties of Mixed Organic Juices Based on Kiwiberry Fruits

Nowadays, the trend related to healthy eating is constantly growing among consumers. The juices based on kiwiberry containing over 20 vital nutrients may have a potential for usage in developing innovative products targeting health-concerned consumers. The aims of the study were: (1) to identify the volatile compounds of kiwiberry juice and its mixes with basic organic juices; (2) to determine the sensory characteristics and level of liking with regard to the tested samples and (3) to select the juice-mix with the highest sensory quality properties and liking. The measurements of volatile compounds in juices were made using a Heracles Neo ultrafast gas chromatograph (HS-GC). The sensory characteristics of the juices were assessed by Descriptive Quantitative Analysis, whereas the consumers’ overall liking was assessed on a 9-point hedonic scale. It was stated that the examined juices differed in the pattern of volatile compounds as well as in the sensory properties and the level of liking. The increasing addition of apple and pear juice to kiwiberry based juices in different ratios contributed to the exposed volatile compounds responsible for floral, sweet and fruity odours. The juice mixes with higher addition of apple or pear juices were more harmonized in terms of sensory image and represented higher levels of overall liking among consumers.

Characteristics of volatile organic compounds produced from five pathogenic bacteria by headspace-solid phase micro-extraction/gas chromatography-mass spectrometry.

The characteristics of volatile compounds from five different bacterial species, Escherichia coli O157:H7, Salmonella Enteritidis, Shigella flexneri, Staphylococcus aureus, and Listeria monocytogenes, growing, respectively, in trypticase soy broth were monitored by headspace solid-phase micro-extraction/gas chromatography-mass spectrometry. The results showed that most volatile organic compounds (VOCs) of five pathogens started to increase after the sixth to tenth hour. Methyl ketones and long chain alcohols were representative volatiles for three Gram-negative bacteria. The especially high production of indole was characterized to E. coli O157:H7. The production of 3-hydroxy-2-butanone was indicative of the presence of two Gram-positive bacteria. Both 3-methyl-butanoic acid and 3-methyl-butanal were unique biomarkers for S. aureus. The population dynamics of individual pathogen could be monitored using the accumulation of VOCs correlated with its growth. And these five pathogens could be distinguishable though principle component analysis of 18 volatile metabolites. Moreover, the mixed culture of S. aureus and E. coli O157:H7 was also investigated. The levels of 3-methyl-butanal and 3-methyl-butanoic acid were largely reduced; while the level of indole almost unchanged and correlated with E. coli O157:H7 growth very well. The characteristics of volatiles from the five foodborne pathogens could lay a fundamental basis for further research into pathogen contamination control by detecting volatile signatures of pathogens.

Determination of emission characteristics of volatile compounds from mosquito repellents (MRs) by headspace and chamber methods, and indoor levels related to use of MRs

Although the use of mosquito repellents (MRs) may lead to several adverse health effects, very limited information is available on exposure to their emissions. As such, the present study evaluated the emission characteristics of volatile pollutants from three different types of MRs (coil, mat, and liquid-vaporiser types) by headspace and/or chamber methods and measured apartment bedroom levels associated with the use of the MRs. By means of a headspace test, 18 to 22 compounds were tentatively identified from mat and liquid MRs. Six toxic/hazardous compounds identified in this headspace test were chosen as target compounds for a further chamber-emission test. An empirical equation was well fitted with time-series concentration levels in a small-scale chamber for all test MRs. Based on the chamber study, the coil MR exhibited the highest emission rate for the target compounds, with the exception of naphthalene, followed by liquid and mat MRs. It is noteworthy that naphthalene was emitted from the liquid MR only at a high emission rate (2.4 mg h−1). A comparison of apartment bedroom levels with predicted values, which were estimated by using the calculated emission data and the one-compartment mass balance equation, suggested that predictions obtained from the chamber study were similar to, or larger than, the measured bedroom levels. Furthermore, the apartment bedroom measurements suggested that the use of coil MR could significantly elevate the indoor levels of four compounds (benzene, ethyl benzene, and m, p-xylene) by up to 1.8 to 1.9 times, while the use of liquid MR could significantly increase the indoor levels of naphthalene by up to 4.2 times. The current findings can provide valuable information for the estimation of the population inhalation exposure to these emissions in indoor environments, and enhance the selection of safer MRs.