The rancidity of rice bran is predominantly triggered by lipophilic enzyme activities. Bran stabilisation and defatting are the typical processes to inactivate the processes that cause rancidity. ...However, little is known about how this impacts the development of volatile compounds related to odour in the rice bran. The effects of the post-milling process on the development of secondary volatile oxidation compounds in the rice bran during storage were investigated. Based on the identified metabolites, there were three possible major pathways in the formation of off-odour and key aroma degradation of the stabilised rice bran during storage, including lipid oxidation, the Maillard reaction, and Strecker degradation. Butanal-2 methyl and furan compounds contributed to the cocoa, nutty, and malty aroma and were considered the important key aroma in the defatted stabilised bran. By contrast, butanal, hexanal, 2-hexenal, butanoic acid, hexanoic acid, pentanoic acid, and heptanoic acid were the discriminant volatile compounds in the non-defatted bran, and they were considered as the markers of rancidity of non-defatted stabilised rice. It can thus be suggested that the defatting process positively contributed to the low abundance of volatile oxidation products that are responsible for bran rancidity by slowing down the formation of lipid-derived oxidation products.
Display omitted
•Three main pathways in the development of volatile compounds in the stabilised rice bran.•The defatting process could slow down the deterioration rate of stabilised rice bran in regard to lipid oxidation.•The defatting process affects the type and abundance of straight-chain aldehydes, strecker aldehydes and furan compounds.
The selection and quality of hops is a major determinant in beer flavour. Brewers acknowledge that distinctive characteristics of different hop varieties can be traced to the composition of their ...essential oils. The difficulty in characterising complex mixtures such as hop oil using 1‐D chromatography is that many compounds co‐elute. With the introduction of comprehensive multidimensional capillary gas chromatography (GC×GC), there is a tremendous improvement in the separation power or peak capacity. Recent work using GC×GC with flame ionisation detection has suggested that there may be over 1,000 compounds in hop oil. This work describes the use of GC×GC combined with TOFMS detection (Leco Pegasus 4D instrument) to analyse Target hop oil. The TOFMS spectral acquisition rate of 60 Hz provided sufficient spectra per peak (2‐D peak base width of 0.1–0.2 s) for identification (119 components were identified with 45 previously unreported compounds). When analysing results, an advantage of GC×GC coupled to TOFMS is that 2‐D chromatograms can be viewed for individual masses that are characteristic of particular functional groups. This allows the analyst to view the various homologous series of compounds although in certain cases coelution may still be present as shown by the esters with mass 75.
► A solvent-free ultrasound assisted extraction of lipids from fresh microalgae. ► Nannochloropsis oculata was chosen as a microalgae model. ► Influence of operating parameters on the extraction ...yields will be studied. ► Response surface methodology was used to study the performance of the extraction.
In order to comply with criteria of green chemistry concepts and sustainability, a new procedure has been performed for solvent-free ultrasound-assisted extraction (UAE) to extract lipids from fresh Nannochloropsis oculata biomass. Through response surface methodology (RSM) parameters affecting the oil recovery were optimized. Optimum conditions for oil extraction were estimated as follows: (i) 1000W ultrasonic power, (ii) 30min extraction time and (iii) biomass dry weight content at 5%. Yields were calculated by the total fatty acids methyl esters amounts analyzed by GC–FID–MS. The maximum oil recovery was around 0.21%. This value was compared with the one obtained with the conventional extraction method (Bligh and Dyer). Furthermore, effect of temperature on the yield was also investigated. The overall results show an innovative and effective extraction method adapted for microalgae oil recovery, without using solvent and with an enable scaling up.
Nowadays, biomass is considered one of the key solutions for the energy transition as a renewable energy source. It can be converted by pyrolysis into bio-oil, which can be used for producing ...biofuels or valuable chemicals. However, bio-oils produced from pyrolysis present high oxygen content and it is necessary to use advanced pyrolysis processes to improve the quality of the bio-oils. In this study, three bio-oils produced by different pyrolysis processes: fast pyrolysis (FP), catalytic fast pyrolysis (CFP), and reactive catalytic fast pyrolysis (RCFP) were analyzed using different analytical techniques. A first bulk analysis was performed using proximate and ultimate analysis and gel permeation chromatography with refractive index and UV detection (GPC-RI and GPC-UV), which provided crucial information on the elemental composition and mass distribution of the bio-oil components. A deeper investigation at the molecular level was performed using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR MS) and High-Performance Thin Layer Chromatography (HPTLC) to determine detailed molecular classification of the bio-oil components. Finally, a fractionation method using flash chromatography (FC) was used to provide a more accurate chemical description. The obtained fractions were analyzed by two-dimensional "comprehensive" gas chromatography (GC×GC) coupled with mass spectrometry (MS) and flame ionization detector (FID), HPTLC, and FTICR MS. The results show that the bio-oils produced from FP and CFP are very similar chemically spoken. The bio-oil from RCFP has less oxygenated products and more unsaturated hydrocarbon species. Therefore, RCFP process was found to be the best process for producing oils with a low O/C ratio.
Display omitted
•Comparison between 3 pyrolysis processes for the conversion of lignocellulosic biomass.•Complementarity of FTICR-MS, GPC-RI-UV, flash chromatography and HPTLC.•Reactive catalytic fast pyrolysis presents high level of hydrocarbon compounds.•Similarity between both fast pyrolysis and catalytic fast pyrolysis bio-oils.
•PLE–GC–MS/MS was implemented for the first time for fungicide analysis in bagasse.•PLE has demonstrated much higher extraction efficiency than UAE.•PLE extracts were directly analyzed without ...further cleanup or concentration.•Target fungicides were found in all the samples at high levels although below MRLs.
Ultrasound-assisted extraction (UAE) and pressurized liquid extraction (PLE) followed by gas chromatography–triple quadrupole-mass spectrometry (GC TQ-MS) were used for the rapid determination of 11 fungicides (metalaxyl, cyprodinil, procymidone, iprovalicarb, myclobutanyl, kresoxim-methyl, benalaxyl, fenhexamide, tebuconazole, iprodione and dimethomorph) in white grape bagasse. The extractions were optimized on real non-spiked samples by means of experimental design and the optimal conditions were selected to achieve the method validation. The PLE procedure showed much higher efficiency than UAE for the target fungicides. Under the selected extraction conditions, PLE showed satisfactory linearity, repeatability and reproducibility. Recoveries for the majority of studied fungicides were higher than 80% with relative standard deviations (RSD) lower than 12%. Limits of detection (LODs) for GC TQ-MS were very low, at the sub ngg−1 for the majority of the target fungicides, well below the European maximum residue limits (MRLs) for wine and table grapes, and vine leaves. Eighteen white grape bagasse samples were analyzed and nine out of eleven targets were detected in the samples. Seven of them were detected in more than 50% of the samples and most samples contained at least four of the target analytes. The most frequently found compounds were tebuconazole and dimethomorph with concentrations between 1.6–130 and 2.0–1788ngg−1, respectively. Some samples showed high levels of many of the studied fungicides (high ngg−1, even μgg−1 for cyprodinil, fenhexamide, iprodione and dimethomorph), but all of them below the European maximum residue limits (MRLs) for wine grapes.
Wild rice (Zizania palustris L.), an aquatic cereal grain, is gaining in popularity among consumers due to its unique nutty, roasted flavor. This study assessed the volatile chemistry of cooked wild ...rice to determine the odor-active compounds using a dynamic headspace system with Tenax trap, gas chromatography–mass spectrometry (GC–MS), GC–olfactometry (GC–O), and descriptive sensory analysis. Traditional brown rice (Oryza sativa L.) was used to contrast with wild rice. Seventy-one volatile compounds were identified by GC–MS; six accounted for 50.2% of the total relative concentration of volatiles. A complex mixture of 33 odor-active compounds was identified by GC–O with nutty and roasted being the dominant aroma notes. Primary contributors to the unique nutty, roasted aroma were benzaldehyde, 2-n-butylfuran, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethyl-6-methylpyrazine, 3-ethyl-2,5-dimethylpyrazine, furfural, methylpyrazine, and 2-pentylfuran. Descriptive sensory analysis illustrated the distinct aroma differences between brown and wild rice in that brown rice was primarily described as having ‘cooked-rice’ and ‘buttery’ aroma attributes and wild rice as ‘nutty’, ‘smoky’, ‘hay-like’, ‘earthy’, and ‘green’. The fermentation and parching steps in the processing of wild rice appear to create the unique nutty, roasted aroma of cooked wild rice. The data provide the foundation upon which wild rice product chemistry and consumer preference can be integrated and used to optimize critical processing steps and select for progeny with superior flavor in wild rice breeding programs.
•The unique nutty, roasted aroma of wild rice was confirmed.•Nine volatiles were found as primary contributors to the unique aroma of wild rice.•Nutty, smoky, hay, earthy, and green were the primary descriptors for wild rice.•Fermentation and parching processing steps appear to create the unique aroma.
Display omitted
•A total of 172 metabolites were identified from almonds.•Almonds exhibit different metabolic profiles after roasting.•Roasting treatment elevated the antioxidant activity of ...almonds.•Elevated antioxidant activity of almonds is associated with fatty acid classes.•Changes in the fatty acid profile of almond oil were analyzed using GC–MS.
Almonds are a commonly consumed nut. They possess significantof nutritional and health benefitsand are commonly processed by roasting. This study aimed to investigatthe effects of roasting on the compound composition and antioxidant activity of almonds. Metabolomics analysis, performed via UPLC-QTOF/MS, and fatty acid analysis, conducted via GC–MS, employed, and the results demonstrated a significant increase in antioxidant activity of post-roasting and in vitro digestion, ranging from 1.16 to 3.44 times. Untargeted metabolomics identified a total of 172 compounds, with notable differences observed in organic oxides, fatty acids, and their derivatives. Correlation analysis identified fatty acids as the primary influencers of changes in antioxidant activity following roasting. Taken together, these findings suggest that roasting enhances the antioxidant activity of almonds, primarily due to alterations in fatty acid analogs, thereby providing valuable insights into optimizing almond consumption for health benefits.
This paper seeks to reconstruct everyday human activities in a Bronze Age Argaric site in southeastern Spain. We used an integrated multi-analytical approach to study residues extracted from 5 ...ceramic pieces and 3 soil samples. The results of these analyses were complemented with archaeological interpretations to produce the first findings on domestic activities four millennia ago at the Peñalosa settlement in Jaén, Spain. The bands observed in FTIR and ATR–FTIR spectra of the archaeological residues showed a peak assignment that confirmed the silicate components of the clay as raw material and the presence of organic matter. The amorphous organic materials were analyzed by GC–MS, HRMS and GC–C–IRMS, and the mineral residues by non-invasive portable X-ray fluorescence (pXRF). We identified α,ω-dicarboxylic and ω-(o-alkylphenyl) alkanoic acids produced by oxidative degradation of unsaturated fatty acids, as well as monocarboxylic acids, n-alkanes, diterpenoid acids, cholesterol, dyes and chemical grape markers. Assignments were based on lipid profile, fatty acid ratios and the δ13C values of C16:0 and C18:0. The results are consistent with the presence of tissues from ruminant (ovine or bovine) and non-ruminant (swine and equine) animals, vegetable oils, waxes, conifer resin and grape seeds. The presence of fish-based fats was suggested in one of the residues. Our evidence also suggests that grape juice or wine may have been consumed at this Bronze Age site. As far as we know this is the first investigation of the organic residues absorbed into an Argaric goblet used in a domestic situation.
•Identification of organic residues by FTIR, ATR–FTIR, GC–MS, HRMS and GC–C–IRMS•A reconstruction about human activities in Spanish Bronze Age was discussed•Correlation between isotopic/molecular analysis and paleopathological studies•The consumption of grape juice or wine 4000years ago is discussed
•The lavender oil production was affected by environmental and developmental factors.•EO content was positively regulated by temperature and flower stage development.•EO content was negatively ...affected by rainfall.•Linalool content was influenced by temperature, flower development and LaLINS expression.•Rainfall during harvest period remarkably decreases linalool production.
The world demand for lavender essential oil is still increasing. Despite of growing interest and the commercial importance of lavender oil it is not clear how environmental and developmental factors influence the optimum period of harvesting lavender flowers for essential oil production. In this report, it was evaluated how the quality and quantity of Lavandula angustifolia cv. Etherio essential oil (EO) is influenced during blooming by environmental factors. It was examined if lavender EO is correlated with gene expression during blooming, targeting to manage the optimum EO harvesting time. The EO content was positively regulated by temperature and flowering stage development while it was negatively affected by rainfall during flowering period. The quality of EO and specifically linalool content was influenced by temperature, flower development, LaLINS expression and rainfall. Although rainfalls remarkably decrease linalool production, the quality of lavender oil was recovered after ten days, suggesting that linalool biosynthesis is regulated during flowering period by both environmental and developmental cues. It is suggested, that the optimum harvesting period to obtain valuable lavender essential oil is when flowering reaches at 60%, ambient temperature is over 26°C and no precipitations were occurred ten days before harvesting.
PDF
