Search Results (721)

Low-density polyethylene (LDPE) is among the most abundant synthetic plastics in the world, contributing significantly to the plastic waste accumulation problem. A variety of microorganisms, such as Cupriavidus necator H16, Pseudomonas putida LS46, and Pseudomonas chlororaphis PA2361, can form biofilms on the surface of LDPE polymers and cause damage to the exterior structure. However, the damage is not extensive and complete degradation has not been achieved. The changes in polymer structure were analyzed using Time-domain Nuclear Magnetic Resonance (TD-NMR), High-Temperature Size-Exclusion Chromatography (HT-SEC), Differential Scanning Calorimetry (DSC), and Gas Chromatography with a Flame Ionization Detector (GC-FID). Limited degradation of the LDPE powder was seen in the first 30 days of incubation with the bacteria. Degradation can be seen in the LDPE weight loss percentage, LDPE degradation products in the supernatant, and the decrease in the percentage of amorphous regions (from >47% to 40%). The changes in weight-average molar mass (Mw), number-average molar mass (Mn), and the dispersity ratio (Đ) indicate that the low-molar mass fractions of the LDPE were preferentially degraded. The results here confirmed that LDPE degradation is heavily dependent on the presence of amorphous content and that only the amorphous content was degraded via bacterial enzymatic action. Full article

The yeast Lachancea thermotolerans has the ability to produce notable amounts of lactic acid and reduce alcoholic strength in fermentation, so it has a considerable potential for mitigating negative impacts of climate changes in winemaking. In this study, a treatment with L. thermotolerans and Saccharomyces cerevisiae in sequential inoculation was compared to a control S. cerevisiae monoculture fermentation of Malvazija istarska (aka Malvasia Istriana) white grape must. Standard physico-chemical parameters of the obtained wines were determined by the OIV methods. Targeted (GC/FID and GC/MS) and untargeted (GC×GC/TOF-MS) gas chromatographic techniques were combined for the analysis of volatile compounds. Phenolic compounds were analyzed by UPLC/QqQ-MS/MS, and proteins by RP-HPLC-DAD, while a sensory analysis of wines was performed by a panel of trained and certified tasters. L. thermotolerans co-fermentation treatment increased the concentration of lactic acid and decreased alcoholic strength. L. thermotolerans increased the concentrations of geraniol, β-ionone, isobutanol, isobutyric acid, ethyl isobutyrate, several major acetates, ethyl lactate, and diethyl succinate, followed by many minor compounds. This wine also contained more hydroxycinnamoyl tartrates, while control S. cerevisiae wine had higher levels of free hydroxycinnamates. The effects on PR proteins were minor. L. thermotolerans co-fermentation slightly enhanced the sensory perception of tropical fruit, herbaceous, tobacco, and buttery odor notes, as well as fullness of body. With the largest number of identified volatile compounds up to date and other results obtained, this study contributes to the better understanding of oenological and especially aromatic potential of L. thermotolerans in white wine production. Full article

The essential oil was obtained by steam distillation, using a Clevenger apparatus, from the pericarp of the fruit of Zanthoxylum lepidopteriphilum from Ecuador. The qualitative and quantitative analyses were performed by gas chromatography coupled with mass spectrometry (GC-MS) and flame ionization detection (GC-FID) on two capillary columns with non-polar DB-5ms and a polar HP-INNOWax stationary phase. Thirty-three components were identified, accounting for 99.62% and 99.30% total essential oil. The essential oil was dominated by oxygenated monoterpenes (90.21–89.21%), respectively. The main constituents of the essential oil were α-thujone (70.26–70.38%), β-thujone (10.78–10.90%), terpinen-4-ol (4.15–4.06%), and sabinene (3.60–4.02%). Enantioselective analysis by GC was realized on a β-cyclodextrin-based chiral column (2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin) in this analysis, determining three couples of enantiomers, which exhibited the compound (1R,4S,5S)-(+)-α-thujone with an enantiomeric excess of 84.40%. Full article

In this study, a high vacuum flavor extraction (HVE) device was developed to address the limitations of traditional extraction methods, such as extended extraction times and artifact generation during high-temperature processes. Firstly, the repeatability and precision of the HVE method were evaluated through quantitative analysis of twelve volatile odor compounds across seven replicate extractions using gas chromatography–flame ionization detection (GC-FID). The results showed that the HVE system achieved a mean relative standard deviation (RSD) of 11.60 ± 1.79% and a recovery rate of 90.55 ± 4.56%, demonstrating its precision and reproducibility. Secondly, the performance of HVE was compared with solvent-assisted flavor evaporation (SAFE) and simultaneous distillation–extraction (SDE) for extracting flavor compounds from fried tilapia mince. The results indicated that HVE was more effective, particularly in extracting aldehydes and pyrazines, which are key contributors to the flavor profile. Finally, sensory evaluations supported these findings, showing that the odor profiles obtained through HVE were most similar to the original sample, with a similarity score of 72.55%, compared to 69.25% for SAFE and 60.29% for SDE. These findings suggest that HVE is a suitable method for the extraction and analysis of volatile compounds in complex food matrices such as fried tilapia mince. Full article

Carpesium macrocephalum, a species native to China, Korea, Japan, and Russia, has been used medicinally in the countries of its origin. Though mono- and sesquiterpenoids are known constituents of C. macrocephalum, the complete analysis of essential oils produced by the roots and aerial parts of the plant has not been published until now. The present study discloses considerable differences in the composition and cytotoxic activity of essential oils distilled from roots and shoots of C. macrocephalum. The GC-MS-FID analyses have led to the identification of 131 compounds in all, of which 114 were found in aerial parts and 110 in the roots of the plants. The essential oil distilled from shoots contained a mixture of nerol and thymol methyl ether (c. 26%), neryl isobutyrate (c. 12%) and linalool (c. 9%) as major constituents, whereas alantolactone (c. 29%), thymol methyl ether (c. 7%) and 2,5-dimethoxy-p-cymene (thymohydroquinone dimethyl ether, c. 7%) predominated in the essential oil obtained from the roots. The oils demonstrated weak antibacterial activity against Staphylococcus aureus and, at concentrations up to 2.08 mg/mL (oil from the aerial parts) and up to 3.38 mg/mL (oil from roots), were inactive against Gram-negative bacteria. The essential oil from the roots of the plant demonstrated strong but not selective cytotoxic activity. Full article

The aim of this study was to determine the activity of common thyme (Thymus vulgare L.), Greek oregano (Origanum vulgare L. ssp. hirtum), and common oregano (Origanum vulgare L. ssp. vulgare) essential oils (EOs) against selected phytopathogenic microorganisms in relation to their chemical profile. The EOs were obtained from the herbs of 2-year-old plants cultivated in the organic farming system in a temperate climate in Central Europe. The EOs’ composition was determined by GC/MS and GC/FID. The investigated species were represented by the following three chemotypes: ‘thymol’ for common thyme, ‘carvacrol’ for Greek oregano, and mixed ‘caryophyllene oxide + β-caryophyllene’ for common oregano. The antimicrobial activity of the EOs was assessed based on minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) values. The plant pathogenic bacteria Pseudomonas syringae, Xanthomonas hortorum, Erwinia carotovora, and fungi: Fusarium culmorum, Alternaria alternata, Botrytis cinerea, Epicoccum purpurascens, Cladosporium cladosporioides, Phoma strasseri, and Pythium debaryanum were tested. The EOs revealed a stronger inhibitory effect against fungal growth in comparison to bacterial growth (MIC: 0.016–2 µL/mL for fungi and 0.125–4 µL/mL for bacteria). Common thyme and Greek oregano EOs indicated stronger antimicrobial power than common oregano EO. These results were associated with the chemical profile of the analysed EOs. The growth of examined bacteria and fungi strains (in particular, X. hortorum, F. culmorum, and P. debaryanum) were negatively correlated with the content of phenolic monoterpenes and monoterpene hydrocarbons. Among the tested strains, P. strasseri turned out to be the most sensitive (MIC 0.016 µL/mL) and E. carotovora the most resistant (MIC 0.250–4 µL/mL) to all investigated EOs. Full article

This study evaluates the essential oil (EO) composition of Piper rivinoides Kunth, a shrub native to the Brazilian tropical rainforest, across different plant parts and developmental phases. The aim was to explore the chemical diversity of EO and its reflection in the plant’s ecological interactions and adaptations. Plant organs (roots, stems, branches, and leaves) at different developmental phases were subjected to hydrodistillation followed by chemical analysis using Gas Chromatography–Mass Spectrometry (GC–MS) and Gas Chromatography–Flame Ionization Detector (GC–FID). The results revealed a relevant variation in EO yield and composition among different plant parts and developmental phases. Leaves showed the highest yield and chemical diversity, with α-pinene and β-pinene as major constituents, while roots and stems were characterized by a predominance of arylpropanoids, particularly apiol. The chemical diversity in leaves increased with plant maturity, indicating a dynamic adaptation to environmental interactions. The study underscores the importance of considering the ontogeny of plant parts in understanding the ecological roles and potential applications of P. rivinoides in medicine and agriculture. The findings contribute to the overall knowledge of Piperaceae chemodiversity and ecological adaptations, offering insights into the plant’s interaction with its environment and its potential uses based on chemical composition. Full article

Terpenes are plant secondary metabolites known for their anti-inflammatory and antioxidant activities. According to ethnobotanical knowledge, Rhododendron luteum Sweet was used in traditional medicine against inflammation. The present study was conducted to determine the triterpene profile and antioxidant and anti-inflammatory activity of supercritical CO₂ (SC-CO₂) extracts of Rhododendron luteum Sweet flower (RLF). An LC-APCI-MS/MS analysis showed the presence of eight pentacyclic triterpenes and one phytosterol in the extracts obtained with pure CO₂ as well as CO₂ with the addition of aqueous ethanol as a co-solvent. Among the compounds detected, oleanolic/ursolic acid, β-sitosterol and 3β-taraxerol were the most abundant. The extract obtained with pure SC-CO₂ was additionally subjected to HS-SPME-GC-FID-MS, which revealed more than 100 volatiles, mainly eugenol, β-phenylethanol, dodecane, β-caryophyllene, estragole and (Z)- and (E)-cinnamyl alcohol, followed by δ-cadinene. The extracts demonstrated significant hyaluronidase inhibition and exhibited varying modes of lipoxygenase and xanthine oxidase inhibitory activities. The studies of RLF have shown that their SC-CO₂ extracts can be a rich source of triterpenes with anti-inflammatory potential. Full article

Elemental analysis is a fundamental method for determining the carbon, hydrogen, nitrogen, sulphur, and oxygen (CHNSO) contents in organic materials. Automated conventional elemental analysers are commonly used for CHNSO determinations, but they face challenges when analysing volatile organic liquids due to sample losses. This present study explores the combination of gas chromatography–mass spectrometry (GC/MS) and gas chromatography–flame ionisation detection (GC/FID) as a more accurate alternative method for elemental analysis of such liquids. Six different liquid samples containing various organic compounds have been analysed using both a conventional elemental analyser (Method 1) and the combined GC/MS–GC/FID method (Method 2). The results showed that Method 1 gave results with significant errors for carbon (by more than ±10 wt%) and oxygen (by up to ±30 wt%) contents due to volatile losses leading to inaccurate “oxygen-by-difference” determinations. In contrast, Method 2 gave more accurate and consistently representative elemental data in a set of simulated samples when compared to theoretical elemental data. This work proposes the use of the GC/FID method as a reliable alternative for CHNSO analysis of volatile organic liquids and suggests that employing the GC/FID technique can mitigate the common errors associated with conventional CHNSO analysis of such samples. However, successfully using Method 2 would depend on the skills and experience of users in qualitative and quantitative organic chemical analyses by gas chromatography. Full article

Although PDO Pecorino Sardo is one of the oldest traditional cheeses of Sardinia, Italy, data on its nutritional properties and food safety are lacking. In particular, significant amounts of lactose and galactose may be a health concern for consumers. The primary objective of this study is to quantify, using a validated GC-FID method, the residual lactose and galactose content in “maturo” (i.e., ripened for at least two months) Protected Denomination of Origin (PDO) Pecorino Sardo cheese. A statistically representative sampling from seven dairies distributed throughout Sardinia has been selected for this aim. In addition to lactose and galactose, two of their metabolites (i.e., glucose and tagatose, respectively) and a bioactive polyol like myo-inositol were quantified. The concentration of lactose (mean 26 mg kg⁻¹, range 4–90 mg kg⁻¹) was below the strictest limit set in the European Union (i.e., 100 mg kg⁻¹), while the galactose content was found to be in an amount (mean: 76 mg kg⁻¹, range: 10–200 mg kg⁻¹) that even patients afflicted with severe galactosemia, albeit with some circumspection, could consume this cheese. Ripening (two to four months) had no significant effect on the amount of all analytes, while a slight decrease in galactose levels was observed during the manufacturing season. Finally, the amounts of glucose, tagatose, and myo-inositol are constant in the range of a few tens of mg kg⁻¹. Full article

Piper mollicomum Kunth (Piperaceae) plays a vital role in the preservation of the Brazilian Atlantic Forest by contributing to the regeneration of deforested areas. Recent scientific investigations have analyzed the chemical constituents and seasonal dynamics of essential oils (EO) from various Piper L. species, highlighting the need to elucidate their chemical–ecological interactions. This study aims to expand the chemical–ecological knowledge of this important taxon in neotropical forests, using P. mollicomum as a model. The methodologies employed include the collection of plant material, EO extraction by hydrodistillation, analysis of EO by gas chromatography–mass spectrometry (GC–MS) and gas chromatography–flame ionization detector (GC–FID), recording the frequency of visits by potential pollinators and microclimatic variables, and by conducting calculations of chemodiversity and chemophenetic indices. Chemical analyses indicated that the diversity of EO and environmental factors are linked to the activities of potential pollinators. In the Tijuca Forest, P. mollicomum revealed significant interactions between its volatile constituents and microclimatic variables, showing that the chemodiversity of the leaves and reproductive organs correlates with pollinator visitation. Additionally, a notable difference in chemical evenness was observed between these vegetative structures. The chemophenetic indices by Ramos and Moreira also revealed correlations with chemical diversity. Full article

In this study, amino-modified micro-mesoporous silica (NH₂-MMS) with hierarchical pores was prepared by modifying micro-mesoporous silica ZSM-5 with 3-aminopropyltriethoxysilane and used as an adsorbent in solid-phase extraction to analyze free fatty acids (FFAs) in krill oil during storage for an initial time. The Brunner Emmet Teller adsorption experiment and Fourier transform infrared spectroscopy demonstrate that NH₂-MMS, with a hierarchical pore structure, was successfully synthesized. The adsorption experiments, especially static adsorption, indicate that the absorption ability of the prepared NH₂-MMS, with a hierarchical pore structure, toward FFAs was better than that of traditional amino-modified mesoporous silica (SBA-15) with a mesoporous structure at all temperature and concentrations. Fairly low limits of detection (0.06–0.15 μg g⁻¹), acceptable recoveries (85.16–94.31%), and precision (0.08–5.26%) were attained under ideal circumstances. Moreover, NH₂-MMS has the advantages of easy preparation and being environmentally friendly. As a result, this method offers an alternative to the current method for determining FFAs in different kinds of oil specimens. Full article

The volatile components emitted by fresh aromatic flowers of Plumeria rubra L., harvested in southern Ecuador during three different months were determined to evaluate the fluctuation of secondary metabolites. The volatile compounds were analyzed using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography coupled to mass spectrometry (GC–MS) and a flame ionization detector (GC–FID) using two types of columns: a non-polar (DB-5ms) and polar column (HP-INNOWax). The principal chemical groups were hydrocarbon sesquiterpenes (43.5%; 40.0%), oxygenated sesquiterpenes (23.4%; 26.4%), oxygenated monoterpenes (14.0%; 11.2%), and hydrocarbon monoterpenes (12.7%; 9.3%). The most representative constituents were (E,E)-α-Farnesene (40.9–41.2%; 38.5–50.6%), (E)-nerolidol (21.4–32.6%; 23.2–33.0%), (E)-β-ocimene (4.2–12.5%; 4.5–9.1%), (Z)-dihydro-apofarnesol (6.5–9.9%; 7.6–8.6%), linalool (5.6–8.3%; 3.3–7.8%), and perillene (3.1–5.9%; 3.0–3.2%) in DB-5ms and HP-INNOWax, respectively. Finally, we reported for the first time the enantiomeric distribution of P. rubra flowers, where the enantiomers (1R,5R)-(+)-α-pinene, (S)-(−)-limonene, (S)-(+)-Linalool, and (1S,2R,6R,7R,8R)-(+)-α-copaene were present as enantiomerically pure substances, whereas (S)-(+)-(E)-Nerolidol and (R)-(+)-(E)-Nerolidol were observed as scalemic mixtures. This study provides the first comprehensive and comparative aroma profile of Plumeria rubra cultivated in southern Ecuador and gave us a clue to the variability of P. rubra chemotypes depending on the harvesting time, which could be used for future quality control or applications in phytopharmaceutical and food industries. Full article

The exposure of humans to polycyclic aromatic hydrocarbons (PAHs) through fruits is a scarcely investigated topic. The atmospheric deposition of PAHs could contribute to such an issue. The present paper would like to propose an easy, fast, and routinary analytical method to extract and quantify PAHs in apples, pears, and grapes. Dispersive liquid–liquid microextraction allowed us to recover PAHs ranging between 68.0 ± 1.2 and 96.2 ± 0.8% from fruit. Gas chromatography equipped with flame ionization detector analysis showed satisfactory analytical parameters, with details like R² > 0.9912 in a concentration range of 0.5–500 µg mL⁻¹, with a variability ranging within 0.7–2.3%. Rural fruit samples were found to be more contaminated by PAHs compared to urban samples, likely due to the use of non-green fuels in rural areas considered in this study. Further in-depth research on this topic is strongly recommended due to the relevance of fruits in the Mediterranean diet. Full article

Using animal manure in organic systems can improve the quality of agricultural products, especially medicinal plants. In this study, the impact of different types and levels of animal manures on hyssop plant biomass and essential oil yield and profile was assessed. Three supply levels (Low, Medium, and High) were tested for poultry (Np), sheep (Ns), and cattle (Nc) manures. Through GC-MS and GC-FID analysis, 24 chemical constituents were identified in the hyssop essential oil, accounting for 93.7–97.8% of the total composition. The Medium-Nc and High-Np treatments had essential oil content ranging from 0.98% to 1.45%, significantly different from the control treatment at 1.17%. Essential oil yield in Low-Np, Medium-Np, and High-Np was 47.5, 53.8, and 49.2 kg ha⁻¹, respectively, showing increases of 42.5%, 61.6%, and 47.7% compared to the control. Medium-Nc and High-Nc treatments had the most potent antioxidant properties compared to the control. Different amounts of poultry, sheep, and cattle manures led to distinct differences in essential oil compounds, categorizing the manure treatments into three groups. Medium-Np had 44% more air-dried biomass than the control, while no significant difference was found in air-dried herbal product levels among sheep and cattle manures. Taken together, farmers focusing on biomass and essential oil should opt for Medium poultry manure. The pharmaceutical industry should explore other fertilizer options based on secondary metabolite needs. Full article