•Developed analytical methods for the surveillance of e-cigarette products.•The use of LC and GC methods allows for determination of 88 flavouring substances.•Fully validation of the method was made ...The results enable a comprehensive assessment of the danger faced by the consumer.
Flavouring compounds are an essential part of e-liquid products for cigarettes. In general, they are regarded as safe for ingestion, but they may have unrecognized risks when they are inhaled. In some cases, manufactures do not currently abide by the Tobacco Products Directive (2014/40/EU) and do not declare the detailed contents of e-liquids on their labels. To help evaluate the health impact of flavouring substances, there is a need for comprehensive approaches to determine their concentrations in e-liquids. For this purpose, a GC-EI-MS method was developed and validated for the simultaneous determination of 46 commonly used flavour additives in e-liquids. The proposed method performed well in terms of the key validation parameters: accuracy (84–113%), inter-/intra-day precision: 0.1–10% and 1–11%, respectively, and sensitivity (limit of detection: 3–87ng/mL). The sample preparation step was based on a simple “dilute & shoot” approach. This study is a complementary method to the LC–MS/MS procedure described in Part I. Both approaches are suitable for the comprehensive determination of 88 flavouring compounds and nicotine and can be used as tools for the rapid evaluation of the quality and safety of e-cigarette products.
Fennel (Foeniculum vulgare Mill.) is widely cultivated and used as a culinary spice. In this work, the chemical composition of the essential oil obtained by hydrodistillation of fennel seeds was ...analyzed by gas chromatography-mass spectrometry (GC–MS), and 28 components were identified. Trans-anethole (68.53%) and estragole (10.42%) were found to be the major components. The antibacterial activity, minimum inhibitory concentration (MIC), and minimum bactericide concentration (MBC) of essential oil against several food-borne pathogens were evaluated. The results showed that the gram positive and gram negative strains of bacteria had different sensitivities to essential oil of fennel seeds, the essential oil exhibited antibacterial activity against Staphylococcus albus, Bacillus subtilis, Salmonella typhimurium, Shigella dysenteriae and Escherichia coli according to the results of MIC and MBC. Among these bacteria, S. dysenteriae was the most sensitive to essential oil, showing the lowest MIC and MBC values of 0.125 and 0.25 mg/mL respectively. In addition, kill-time assay also showed that the essential oil had a significant effect on the growth rate of surviving S. dysenteriae. We concluded that the mechanism of action of the essential oil against S. dysenteriae might be described as essential oil acting on membrane integrity according to the results of the leakage of electrolytes, the losses of contents (proteins, reducing sugars and 260 nm absorbing materials) assays and electron microscopy observation.
•Analyzed the chemical compositions of essential oil from fennel seeds.•Investigated the antibacterial activity of essential oil from fennel seeds.•Evaluated the action mechanism of essential oil against Shigella dysenteriae.
Sixty compounds of
Lavandula angustifolia L
. cultivated in Friuli Venezia Giulia (North-East Italy) were identified and quantified by GC-MS and GC-FID from essential oils obtained by means of ...hydrodistillation, and from extracts obtained by supercritical CO
2 extraction (SFE) and ultrasound-assisted extraction (US). Using absolute calibration, a true quantification of 1-8 cineol, camphor, linalool, linalyl acetate and β-caryophyllene was carried out. The best extracts, in terms of amount of isolated compounds, flavour quality and stability were those obtained with SFE. Sonication performed at low amplitude for 5
min offered respect to high amplitude a promising alternative to hydrodistillation as a source of lavender flavouring ready to use for alcoholic beverages or/and confectionery products.
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•Milk fat content (6% and 2.8%) and homogenization affected milk flavour profiles.•The highest acids production was in 6% fat milks with R. Mihei lipase.•R. Miheie lipase favored ...esters production in 2.8% fat milks.•EstA enzyme incresead biosynthesis of esters in homogenized 6% fat milks.
The use of esterase/lipase enzymes of different origins in food industry is a widely employed strategy to enhance the formation of characteristic aromatic compounds derived from fat and diversify flavour. In the present work, we studied EstA enzyme of Enterococcus faecalis and a high purity Rhizomucor miehei lipase (Palatase). EstA was obtained recombinantly in Escherichia coli BL21 (DE3), and optimum esterase activity was detected at pH 6.75 and 40 °C. We evaluated the effect of the enzymes on milk mixtures prepared with different fat contents (2.8 and 6%) and structure (native or homogenized) on volatile compounds profiles. The milk fat structure before and after the application of low homogenization was characterized by dynamic light dispersion and microscopy. Native milk fat mixtures presented particles of 4.6 μm and 184 nm and homogenized mixtures had particles of 1.4 μm and 258 nm; microscopy images were in concordance with these results. Fifteen volatile compounds were identified, including ketones, esters, alcohols, and acids. We showed the key role of milk fat levels and microstructure in the nature of the volatile compounds produced by the R. miehei enzyme. Both in native or homogenized states, the highest content of fat favored a higher production of acids whereas the lowest fat level favored a higher esters production along with a more balanced volatile profile. For EstA enzyme, results showed a limited action on fat, as biosynthesis of esters only increased with the highest fat level homogenized.
► Citrus essential oils acted as plasticiser in gelatin films. ► Essential oils could lower water permeability of gelatin films. ► Gelatin film incorporated with essential oils possessed ...antioxidative activity.
Properties of protein-based film from fish skin gelatin incorporated with different citrus essential oils, including bergamot, kaffir lime, lemon and lime (50% based on protein) in the presence of 20% and 30% glycerol were investigated. Films containing 20% glycerol had higher tensile strength (TS) but lower elongation at break (EAB), compared with those prepared with 30% glycerol, regardless of essential oils incorporated (p<0.05). Films incorporated with essential oils, especially from lime, at both glycerol levels showed the lower TS but higher EAB than the control films (without incorporated essential oil) (p<0.05). Water vapour permeability (WVP) of films containing essential oils was lower than that of control films for both glycerol levels (p<0.05). Films with essential oils had varying ΔE* (total colour difference), where the highest value was observed in that added with bergamot essential oil (p<0.05). Higher glycerol content increased EAB and WVP but decreased TS of films. Fourier transforms infrared (FTIR) spectra indicated that films added with essential oils exhibited higher hydrophobicity with higher amplitude at wavenumber of 2874–2926cm−1 and 1731–1742cm−1 than control film. Film incorporated with essential oils exhibited slightly lower thermal degradation resistance, compared to the control film. Varying effect of essential oil on thermal degradation temperature and weight loss was noticeable, but all films prepared using 20% glycerol had higher thermal degradation temperature with lower weight loss, compared with those containing 30% glycerol. Films added with all types of essential oils had rough cross-section, compared with control films, irrespective of glycerol levels. However, smooth surface was observed in all film samples. Film incorporated with lemon essential oil showed the highest ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP) (p<0.05), while the other films had lower activity. Thus, the incorporation of different essential oils and glycerol levels directly affected the properties of gelatin-based film from fish skin.
Combining antimicrobial agents such as plant essential oils directly into a food packaging is a form of active packaging. In this work chitosan-based films containing cinnamon essential oil (CEO) at ...level of 0.4%, .0.8%, and 1.5% and 2%
(v/v) were prepared to examine their antibacterial, physical and mechanical properties. Scanning electron microscopy was carried out to explain structure–property relationships. Incorporating CEO into chitosan-based films increased antimicrobial activity. CEO decreased moisture content, solubility in water, water vapour permeability and elongation at break of chitosan films. It is postulated that the unique properties of the CEO added films could suggest the cross-linking effect of CEO components within the chitosan matrix. Electron microscopy images confirmed the results obtained in this study.
This work focuses on the encapsulation of essential oils into nanometric delivery systems for incorporation into fruit juices, in order to enhance their antimicrobial activity while minimizing the ...impact on the quality attributes of the final product. A terpenes mixture and d-limonene were encapsulated into nanoemulsions based on food-grade ingredients, prepared by high pressure homogenization at 300 MPa.
The effect of the delivery systems on the antimicrobial activity of terpenes was investigated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for three different classes of microorganisms (Lactobacillus delbrueckii, Saccharomyces cerevisiae, Escherichia coli). The increase of the antimicrobial activity resulted to depend on the formulation and mean diameter of the delivery systems as well as on the microorganisms class. Additionally, GC–MS analysis revealed that high intensity processing for nanoemulsion production may affect the chemical stability of several active compounds.
The application of the most efficient antimicrobial nanocapsules was tested in pear and orange juices inoculated with L. delbrueckii. Due to the higher antimicrobial activity of the nanoencapsulated compounds, lower antimicrobial concentrations are required for a bactericidal action under accelerated aging at 32 °C, with a minimal alteration of the organoleptic properties of the juice.
The influence of the drying method on volatile compounds of
Rosmarinus officinalis was evaluated. The drying methods tested were convective (CD) and vacuum-microwave (VMD), as well as a combination ...of convective pre-drying and VM finish-drying (CPD–VMFD). Rosemary drying kinetics was described by a simple exponential model for CD and VMD, while VMFD kinetics consisted of two periods: linear until a critical point and exponential beyond that point. Volatile compounds of rosemary samples were extracted by steam-hydrodistillation and analyzed by GC–MS. Thirty-four compounds were tentatively identified, with α-pinene, bornyl acetate, camphene and 1,8-cineole being the major components. The total volatiles concentration of fresh rosemary (135
g
kg
−1) decreased considerably during both CD (87.2
g
kg
−1) and VMD (61.9
g
kg
−1). CPD–VMFD was the best option for drying rosemary because the time required was relatively short (30
min), and the aroma quality was good according to both instrumental (100
g
kg
−1) and sensory analyses.
This study aimed to elucidate the physico-chemical characteristics of EO–BCD inclusion complexes and their resulting antimicrobial activity. Cinnamon bark extract, trans-cinnamaldehyde, clove bud ...extract, eugenol, and a 2:1 (trans-cinnamaldehyde:eugenol) mixture were microencapsulated by the freeze-drying method. EO–BCD complexes were characterized for particle size, morphology, polydispersity index, entrapment efficiency, and phase solubility. All particles showed a spherical shape, smooth surface, no significant differences in size distribution and strong tendency to agglomerate. The entrapment efficiencies ranged from 41.7 to 84.7%, where pure compounds were higher (p < 0.05) than extracts. The oils and their BCD complexes were analyzed for their antimicrobial activity against Salmonella enterica serovar Typhimurium LT2 and Listeria innocua. All antimicrobials effectively inhibited bacterial growth within the concentration range tested, except free eugenol. The EO–BCD complexes were able to inhibit both bacterial strains at lower active compound concentrations than free oils, likely due to their increased water solubility that led to increased contact between pathogens and essential oils. The cinnamon bark and clove bud extract BCD complexes were the most powerful antimicrobials, despite showing the lowest entrapment efficiencies amongst the oils. Results suggest that the application of these antimicrobial complexes in food systems may be effective at inhibiting pathogens.
► EO–BCD inclusion complexes physico-chemical and antimicrobial properties were studied. ► EO–BCD inclusions inhibited bacteria at lower concentrations compared to free oils. ► Cinnamon bark and clove bud BCD inclusions showed superior antimicrobial activity. ► Encapsulation enhanced antimicrobial activity of EOs against Listeria and Salmonella spp.
► Preparing a functional bionanocomposite containing nanoclay and rosemary from chitosan. ► Studying combined effect of nanoparticle and essential oil on film properties. ► Decreasing water ...sensitivity of chitosan-based films with incorporating nanoclay and rosemary essential oil. ► Improving the mechanical properties of the films using nanoclay and the essential oil. ► Improving antibacterial and total phenol content of the nanocomposite using the essential oil.
Montmorillonite (MMT) nanoclay and rosemary essential oil (REO) were incorporated into chitosan film to improve its physical and mechanical properties as well as antimicrobial and antioxidant behavior. The MMT weight percent relative to chitosan was varied from 1 to 5 and was activated by three REO levels (0.5%, 1%, and 1.5% v/v), and their impact on physical, mechanical, and barrier properties of the chitosan films was investigated. Total phenolic and antimicrobial activity were also evaluated. Microstructure of chitosan/MMT–REO nanocomposites was characterized through X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that incorporating MMT and REO into chitosan improves water gain, water vapor permeability, and solubility of the chitosan film by more than 50%. It was also shown that the combined effect of clay and REO improves significantly the tensile strength and elongation of chitosan (p<0.05). The XRD and FTIR results confirmed that the improvements are related to the MMT exfoliation and good interaction between chitosan and MMT in the presence of REO. Antimicrobial properties of the films also improved by REO incorporation in 1.5% v/v.
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