Headspace Gas Research Articles

Comprehensive Evaluation of Ten Actinidia arguta Wines Based on Color, Organic Acids, Volatile Compounds, and Quantitative Descriptive Analysis.

Actinidia arguta wine is a low-alcoholic beverage brewed from A. arguta with a unique flavor and sweet taste. In this study, the basic physicochemical indicators, color, organic acid, and volatile aroma components of wines made from the A. arguta varieties 'Kuilv', 'Fenglv', 'Jialv', 'Wanlv', 'Xinlv', 'Pinglv', 'Lvbao', 'Cuiyu', 'Tianxinbao', and 'Longcheng No.2' were determined, and a sensory evaluation was performed. The findings show that 'Tianxinbao' produced the driest extract (49.59 g/L), 'Kuilv' produced the most Vitamin C (913.46 mg/L) and total phenols (816.10 mg/L), 'Jialv' produced the most total flavonoids (477.12 mg/L), and 'Cuiyu' produced the most tannins (4.63 g/L). We analyzed the color of the A. arguta wines based on CIEL*a*b* parameters and found that the 'Kuilv' and 'Longcheng No.2' wines had the largest L* value (31.65), the 'Pinglv' wines had the greatest a* value (2.88), and the 'Kuilv' wines had the largest b* value (5.08) and C*ab value (5.66) of the ten samples. A total of eight organic acids were tested in ten samples via high-performance liquid chromatography (HPLC), and we found that there were marked differences in the organic acid contents in different samples (p < 0.05). The main organic acids were citric acid, quinic acid, and malic acid. The aroma description of a wine is one of the keys to its quality. A total of 51 volatile compounds were identified and characterized in ten samples with headspace gas chromatography-ion mobility spectrometry, including 24 esters, 12 alcohols, 9 aldehydes, 3 aldehydes, 2 terpenes, and 1 acid, with the highest total volatile compound content in 'Fenglv'. There were no significant differences in the types of volatile compounds, but there were significant differences in the contents (p < 0.05). An orthogonal partial least squares discriminant analysis (OPLS-DA) based on the odor activity value (OAV) showed that ethyl butanoate, ethyl pentanoate, ethyl crotonate, ethyl isobutyrate, butyl butanoate, 2-methylbutanal, ethyl isovalerate, and ethyl hexanoate were the main odorant markers responsible for flavor differences between all the A. arguta wines. Sensory evaluation is the most subjective and effective way for consumers to judge A. arguta wine quality. A quantitative descriptive analysis (QDA) of the aroma profiles of ten grapes revealed that the 'fruity' and 'floral' descriptors are the main and most essential parts of the overall flavor of A. arguta wines. 'Tianxinbao' had the highest total aroma score. The flavor and quality of A. arguta wines greatly depend on the type and quality of the A. arguta raw material. Therefore, high-quality raw materials can improve the quality of A. arguta wines. The results of the study provide a theoretical basis for improving the quality of A. arguta wines and demonstrate the application prospects of HS-GC-IMS in detecting A. arguta wine flavors.

Polyoxometalate-Modified Amphiphilic Polystyrene-block-poly(2-(dimethylamino)ethyl methacrylate) Membranes for Heterogeneous Glucose to Formic Acid Methyl Ester Oxidation.

Herein, we present a new heterogeneous catalyst active toward glucose to formic acid methyl ester oxidation. The catalyst was fabricated via electrostatic immobilization of the inorganic polyoxometalate HPA-5 catalyst H8[PMo7V5O40] onto the pore surface of amphiphilic block copolymer membranes prepared via non-solvent-induced phase separation (NIPS). The catalyst immobilization was achieved via wet impregnation due to strong coulombic interactions between protonated tertiary amino groups of the polar poly(2-(dimethylamino)ethyl methacrylate) block and the anionic catalyst. Overall, three sets of five consecutive catalytic cycles were performed in an autoclave under 90 °С and 11.5 bar air pressure in methanol, and the corresponding yields of formic acid methyl ester were quantified via head-space gas chromatography. The obtained results demonstrate that the membrane maintains its catalytic activity over multiple cycles, resulting in high to moderate yields in comparison to a homogeneous catalytic system. Nevertheless, presumably due to leaching, the catalytic activity declines over five catalytic cycles. The morphological and chemical changes of the membrane during the prolonged catalysis under harsh conditions were examined in detail using different analytic tools, and it seems that the underlying block copolymer is not affected by the catalytic process.

Bio-succinic acid production, up to pilot scale, by fermentation of industrial candy waste with Actinobacillus succinogenes 130Z and its downstream purification process

Nowadays, the global community faces a worldwide challenge concerning the minimization of carbon emissions. Significant efforts are being conducted to apply environmental-friendly processes, such as the production of succinic acid by utilizing waste residual streams through a biorefinery approach. In this context, this study aimed to upscale the fermentative production (batch mode) of succinic acid (SA) by Actinobacillus succinogenes 130Z from an industrial candy residue. Process performance (titer, productivity, yield) was assessed at different operating conditions such as CO2 headspace gas overpressure (0, 0.4, 1.0, and 1.4 atm), initial sugars concentration (about 70, 95, 117 g L−1), yeast (10, 15 g L−1) and MgCO3 (0, 10 g L−1) concentration in fermentation media using two different batches of an industrial candy residue batches. SA concentration varied in the range of 37.78 ± 0.02–39.94 ± 0.04 g L−1 both in lab and pilot trials with yields of up to 0.74 (g g−1). Finally, a successful downstream concept for SA purification (pre-purification, membrane filtration, ion-exchange, vacuum distillation, and crystallization) was investigated. High purity (up to 93.5 ± 1.8 %) and SA crystallization recovery (up to 86.7 ± 3.2 %) was achieved from the fermentation broths.

Comparison of fragrance and flavor components in non-psilocybin and psilocybin mushrooms using vacuum-assisted headspace high-capacity solid-phase microextraction and gas chromatography–mass spectrometry

Vacuum-assisted headspace high capacity solid-phase microextraction (Vac-HS-HC-SPME) coupled with gas chromatography–mass spectrometry (GC–MS) was used to compare the volatile compounds that make up the volatile and semi-volatile components of five psilocybin mushrooms (Psilocybe cubensis), as well as three non-psilocybin mushroom species. Using an untargeted analysis, common volatiles detected consisted of acids, alcohols, aldehydes, ketones, and hydrocarbons. The initial comparison of Vac-HS-HC-SPME and HS-HC-SPME conditions showed 2 times increase in compound response as well as the detection of 8 additional compounds undetected by HS-HC-SPME. Compounds unique to psilocybin mushrooms were 2-methylbutanal, valeraldehyde, benzaldehyde, 3-octen-2-one, 2-methyl-dodecane, and 2‑butyl‑2-octenal. Compounds unique to non-psilocybin mushrooms were 2-methyl-pyrazine, 2,3-butanediol, butyric acid, butyrolactone, benzyl alcohol, 2-pyrrolidinone, and estragole. The commonly shared compound, 1-octen-3-ol, was shown to have a higher compound response among the psilocybin mushroom species.

Effect of CO2 on the preservation effectiveness of chilled fresh boneless beef knuckle in modified atmosphere packaging and microbial diversity analysis

To explore the effect of different concentrations of CO2 in modified atmosphere packaging (MAP) on the preservation shelf life of boneless beef knuckle (BBK), and to deeply study the changes in the bacterial community. In the controlled atmosphere combination, the proportion of O2 in each group is kept at 40%, CO2: 20%–45%, and N2: 15%–60%, the blank control group is set to 40%O2+0%CO2+60%N2. Sensory evaluation, headspace gas, total colony, and physicochemical indicators were measured at the 1st, 3rd, 5th, 7th, 9th, and 11th days of storage, respectively. The results showed that group 25%CO2+35%N2 had the longest shelf life is 9 days. In the analysis of the bacterial community, CO2 significantly inhibited the growth of Pseudomonas from the 3rd day onwards in the group 25%CO2+35%N2. After 4 days of storage, Lactobacillus was the main dominant bacterium, followed by Carnobacterium. Through KEGG metabolic pathway analysis, it was found that during the storage and preservation process, the expression levels of genes related to carbohydrate metabolism and amino acid metabolism in cold fresh BBK were higher than those in other metabolites.

Ethanol Kinetics in the Human Brain Determined by Magnetic Resonance Spectroscopy.

In many parts of the world, ethanol is a widely consumed substance that displays its effect in the brain, the target organ for desired, but also negative impact. In a previous study, the ethanol concentrations were analyzed in different regions of the brain by magnetic resonance spectroscopy (MRS). In this study, the same method is used to demonstrate the kinetics of the ethanol concentration in the human brain after oral ethanol uptake. A drinking study was performed with 10 healthy participants. After the uptake of ethanol in a calculated amount leading to a plasma ethanol concentration of 0.92 g/L (19.95 mM corresponding to a blood ethanol concentration of 0.7 g/kg), brain ethanol concentrations were continuously measured by means of MRS on a 3 Tesla human magnetic resonance imaging (MRI) system. For the data acquisition a single-voxel sLASER sequence was used, with the volume of interest located in the occipital cortex. Intermittently, blood samples were taken and plasma was analyzed for ethanol using headspace gas chromatography with flame ionization detection (HS-GC-FID). The obtained MRS brain ethanol curves showed distinct inter-individual differences; however, a good intra-individual correlation of plasma and brain ethanol concentrations was observed. The results suggest a rapid equilibration between blood and brain. The ethanol concentrations measured in the brain were substantially lower than the measured plasma ethanol results, suggesting an MRS visibility of about 63% for ethanol in brain tissue. The maximum individual ethanol concentrations in the brain (normalized to water content) ranged between 7.1 and 14.1 mM across the cohort, while the highest measured plasma concentrations were in the range between 0.35 g/L (9.41 mM) and 0.95 g/L (20.52 mM).

Gas Evolution Characterization of NiZn Batteries with Residual Gas Analysis

As humanity strives to reduce its impact on the environment, the need for safe, recyclable, and efficient batteries increases. Nickel-Zinc batteries offer a solution to some of the world’s needs with its materials being abundant and recyclable, its ability to discharge at high currents, and its safe and nontoxic materials providing low risk with applications. Nickel-Zinc batteries are rechargeable, have a ZnO anode, a NiOOH cathode, and an aqueous KOH solution as the electrolyte. During cycling, Ni-Zn cells produce and consume H2 and O2 gas. This gassing behavior has not previously been characterized. The goal of this research was to analyze this gassing behavior by measuring the partial pressure vs. time of a cell’s headspace gas during cycling. The headspace gas was leaked into a vacuum chamber and analyzed with an RGA quadrupole mass spectrometer. The primary trend of the H2 gassing was that the cell produced hydrogen during charging and was rapidly consumed at the end of charging, which indicated recombination with oxygen at an internal catalyst coil. The consumption stopped about midway through discharging and began to produce the H2 gas again. The O2 gassing peaked as H2 was consumed and slowly tapered off during the rest of the discharge and charge. The curvature of these partial pressure plots was dependent of the cycle number and charge rate. The eventual goal of this research is to use the gassing data to indicate the different phases of the electrode materials present throughout cycling. Figure 1

(Invited) Consumable Fe Anode for Use in Direct Electrolytic Reduction of Spent Oxide Fuel

The direct electrolytic reduction (DER) process can be used to reduce UO2 to U metal in a molten LiCl-Li2O electrolyte. In the baseline process, UO2 is loaded in a steel basket that serves as the cathode, while O2 gas is generated at a Pt anode. The use of Pt for anodes is non-optimal because of its cost and tendency to corrode via lithium platinate formation during the DER process. Other inert metals and cermets for DER anodes have been extensively researched to reduce the cost. Alternatively, reactive anodes may be considered that form disposable metal oxides rather than O2 gas. Thus, we investigated the behavior of pure iron rods as anodes for this process. Experiments were performed using a LiCl-2wt%Li2O electrolyte at 650oC in an Ar atmosphere glove box with <10 ppm O2 and H2O. UO2 powder was loaded into a stainless-steel cathode basket. A 7.56-mm diameter iron rod was used as the anode. Anode and cathode potentials were measured relative to a Ni/NiO reference electrode encased in a MgO tube with a porous MgO plug. The cell was run via controlled anode potential with increments from 0.2–1.0 V versus Ni/NiO. The headspace gas was sampled during experiments and analyzed for O2. Throughout the experiment, the cathode potential was consistent with either direct reduction of UO2 or reduction of Li2O, which forms Li that will also reduce UO2 to U metal. LECO oxygen analysis indicated 32% reduction of UO2 with a cell efficiency of 37%. Li2O concentration remained constant in the salt; thus, net oxidation must have occurred at the anode. The Fe anode was pulled out of the salt and photographed after stages of holding the potential at 0.2–1.0 V versus Ni/NiO in 0.1 V increments for about 11-12 min at each stage. Yet unidentified metal oxides were observed on the anode surface after holding at potentials of 0.4 V and 0.6–1.0 V. O2 was detected in the headspace gas when the anode potential was increased to 1.0 V. Thus, iron oxides form at lower potentials, while O2 gas formation occurs at a threshold potential. O2 formation may be enabled by the oxide layer passivating the iron against further oxidation. Results of ICP-MS of salt samples taken throughout the experiment showed no increase in Fe concentration in the salt. A metallic deposit formed on the outside of the cathode basket, implying some electrotransport occurred from the anode to the cathode. The results of this study show that cheap, disposable iron anodes are promising for the DER process. After an initial stage of formation of an iron oxide phase on the surface of the anode, O2 gas forms at a sufficiently high potential (1.0 V versus Ni/NiO). Further work is needed to achieve a more detailed mechanistic understanding of the effect of anode potential on specific reactions at the anode. Optimization of the anode potential may serve to promote O2 formation and minimize the rate of consumption of iron anodes.DISCLAIMERThis work of authorship and those incorporated herein were prepared by Consolidated Nuclear Security, LLC (CNS) as accounts of work sponsored by an agency of the United States Government under Contract DE-NA-0001942. Neither the United States Government nor any agency thereof, nor CNS, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility to any non-governmental recipient hereof for the accuracy, completeness, use made, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency or contractor thereof, or by CNS. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency or contractor (other than the authors) thereof.COPYRIGHT NOTICEThis document has been authored by Consolidated Nuclear Security, LLC, under Contract DE-NA-0001942 with the U.S. Department of Energy/National Nuclear Security Administration, or a subcontractor thereof. The United States Government retains and the publisher, by accepting the document for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this document, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, or allow others to do so, for United States Government purposes.

Optimization of the Use of a Commercial Phage-Based Product as a Control Strategy of Listeria monocytogenes in the Fresh-Cut Industry.

A commercial phage biocontrol for reducing Listeria monocytogenes has been described as an effective tool for improving fresh produce safety. Critical challenges in the phage application must be overcome for the industrial application. The validation studies were performed in two processing lines of two industry collaborators in Spain and Denmark, using shredded iceberg lettuce as the ready-to-eat (RTE), high process volume product. The biocontrol treatment optimized in lab-scale trials for the application of PhageGuard ListexTM was confirmed in industrial settings by four tests, two in Spain and two in Denmark. Results showed that the method of application that included the device and the processing operation step was appropriate for the proper application. The proper dose of Phage Guard ListexTM was reached in shredded iceberg lettuce and the surface was adequately covered for the successful application of phages. There was no impact on the headspace gas composition (CO2 and O2 levels), nor on the color when untreated and treated samples were compared. The post-process treatment with PhageGuard ListexTM did not cause any detrimental impact on the sensory quality, including flavor, texture, browning, spoilage, and visual appearance over the shelf-life as the phage solution was applied as a fine, mist solution.

Comparative analysis of the aroma profile of pineapple beers brewed with juice added at different times

Pineapple juice was added at three different points in the brewing process, (i) wort, (ii) toward the end of fermentation and (iii) at the beginning of maturation. The physicochemical properties, taste and aroma of the three fruit beers was compared to a control beer without addition of pineapple juice. The beers analysed using an electronic nose (E-nose), headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). Of the three fruit beers, esters characteristic of pineapple aroma was found in the beer produced with juice added late during primary fermentation. Further, the abundance of esters - isoamyl acetate, ethyl butyrate, ethyl acetate, ethyl hexanoate and phenethyl acetate - was higher. Sensory analysis showed the beer produced from the addition of juice late in fermentation had a superior aroma and was the most preferred in sensory testing. These results provide technical support for process optimisation and for improving the aroma of fruit beers.

Use of elemental profiles determined by energy-dispersive X-ray fluorescence and multivariate analyses to detect adulteration in Ceylon cinnamon.

The price of Cinnamomum verum (Ceylon cinnamon) is around twice as high as that of the other cinnamon varieties commonly grouped under the name cassia cinnamon, making the former spice an attractive target for fraudsters. This work demonstrates that elemental profiles obtained by energy-dispersive X-ray fluorescence in combination with multivariate analyses can be used as a screening method to detect Ceylon cinnamon adulteration. Thirty-six elements were analysed in 52 commercially available cinnamon samples, 29 Ceylon, 8 cassia, and 15 for which no indication about variety was provided. Fifty-eight percent of the samples were either adulterated or did not meet international quality criteria. Four of the ground cinnamon samples labelled as Ceylon cinnamon were found to be pure cassia or a mixture with a high cassia content, and 26 samples were suspected of other types of adulteration including replacement of bark with other parts of the cinnamon tree. Headspace gas chromatography-mass spectrometry and ash determination by thermogravimetric analysis confirmed the conclusions reached by elemental analysis. Only one sample labelled as Ceylon cinnamon and that according to its volatile composition was cassia cinnamon was not flagged as suspicious by elemental analysis.

Modulating Natural Methane Release from Rumen Fermentation through the Use of Ficus glomerata Leaf Tannins in Murrah Buffalo (Bubalus bubalis)

Enteric fermentation is one of the largest contributors of methane release to the environment from the livestock sector. Plant bioactive compounds can modulate rumen fermentation for reduced methanogenesis and fatty acid biohydrogenation. The present study investigates the effects of tannin extract from Ficus glomerata (FG) leaves on the rumen fermentation, methanogenesis, feed digestibility and fatty acid biohydrogenation of a total mixed ration with the aim of developing a feed supplement for enhanced livestock production and product quality with lower methane emission. The tannin extract (70% aqueous acetone extract) of FG leaves in the total mixed ration (oat hay/concentrate mixture; 1:1) was studied at four graded dose regimens (0.0 (control), 0.25 mL (FG-0.25), 0.50 mL (FG-0.50) and 1.0 mL (FG-1.0) per 60 mL of buffered rumen fluid) in three replicates for each treatment in a radio-frequency-based automatic gas production system (ANKOM-RF) at 39 °C for 24 h following the standard in vitro gas production protocol. The total gas production (mL or mL/g incubated dry matter (DM)) was gradually reduced (p &lt; 0.01) at dose levels of FG-0.50 and FG-1.0; however, it remained intermediary and comparable (p &gt; 0.05) for FG-0.25 with the control and FG-0.50. Compared to the control, the methane concentration (%) in the head space gas, as well as the total methane production (mL or mL/g DM incubated, or mL/g DM digested), were found to be gradually reduced (p &lt; 0.01) with increasing doses (0.25–1.0 mL) of FG extract. The reduced (p &lt; 0.05) feed degradability at higher levels (0.50–1.0 mL) of FG extract supplementation and the comparative (p &gt; 0.05) effects with the control at a lower level of supplementation (FG-0.25) are suggestive of the dose-responsive detrimental effects of tannins on fibrolytic microbes in the rumen. However, the ammonia concentration decreased (p &lt; 0.05) in all of the incubations compared to the control. Among the volatile fatty acids, acetate remained comparable (p &gt; 0.05) with enhanced (p &lt; 0.05) propionate at a lower dose (FG-0.25); however, a dose-dependent reduction was evident at higher dose levels (FG-0.50 and FG-1.0). The production of stearic acid (C18:0), which is a product of the rumen biohydrogenation process, was reduced (p &lt; 0.05), irrespective of the concentration of the FG extract. Compared to the control, the concentration of t-vaccenic acid (C18:1), which is a precursor of conjugated linoleic acid (CLA) in animal products, was increased in all the FG-extract-supplemented groups. It may be concluded that Ficus glomerata leaf tannins can modulate rumen fermentation for reduced methanogenesis and fatty acid biohydrogenation in a total mixed ration. As a higher level of inclusion negatively affects feed digestibility, a lower dose (0.25 mL FG extract per 60 mL fermentation fluid or 4.17 mL FG extract per L of fermentation fluid) is suggested to achieve desirable effects on methane abatement (30%) and an improvement in fatty acid profiles in animal products.

Mapping and analysis of volatomes from pearl millet (Pennisetum gaucum L.) grains during different storage conditions with solid‐phase microextraction–gas chromatography–mass spectrometry

AbstractBackground and ObjectivesVolatile organic compounds (VOCs) are considered biomarkers for the metabolic activities of biological entities. This work analyzed the impact of storage period and temperature (5°C, 25°C, and 45°C) on the VOC profile of pearl millet grains stored for 120 days through headspace gas analysis using solid‐phase microextraction–gas chromatography–mass spectroscopy (SPME‐GC‐MS).FindingsThe major groups identified in the pearl millet grains belonged to acid, alcohol, aldehyde, alkane, and ester groups. VOC data were analyzed using principal component analysis, partial least square discriminant analysis (PLS‐DA), cluster heat map, and network analysis of metabolite–metabolite interactions. The PLS‐DA could distinctly classify the VOCs generated with respect to different storage conditions. The VOCs generated during storage indicated the four most significant metabolic pathways, that is, fatty acid biosynthesis, cutin, suberine and wax biosynthesis, arginine biosynthesis, and arginine and proline metabolism.ConclusionsThe SPME‐GC‐MS protocol developed for mapping VOC through this study and the classification protocol developed can be used for developing quality monitoring systems in pearl millet grains.Significance and NoveltyIdentification of VOCs at a particular period will be helpful for the recommendation of appropriate remedial measures at the right time to avoid the spoilage of grains.

Activity of volatiles induced by microbes and natural plants stifled the growth of Pythium aphanidermatum - the damping off in Tomato

BackgroundVolatilomes from natural plants and microbes imparts diverse antifungal properties to suppress the growth of plant pathogens and therefore can be a suitable alternative of chemical fungicides. The present experiment was to study effect of volatiles produced by natural plants and microbes on the fungal growth of Pythium aphanidermatum, which is a tomato seedling pathogen.ResultsIsolate of P. aphanidermatum, causing damping off in tomato were isolated and incubated at 25 ± 2 °C. The isolate was tested for the anti-oomycetes activities of volatiles in vitro. The volatiles produced by the leaves of Mentha spicata and Cymbopogon citratus showed the maximum inhibitory effect of 45.56 and 24.70 percent, respectively on the mycelial growth of P. aphanidermatum, whereas, the pathogen was not inhibited on exposure to the volatiles of macro-basidiomycetes fungi. The volatiles of T. asperellum showed the maximum inhibitory effect of 69.26 percent against P. aphanidermatum. The study also included the identification of Volatile Organic Compounds (VOCs) involved in the suppression of pathogens by Headspace Gas Chromatography Mass Spectrometry (HS GCMS). The results revealed the production of carvone by the leaves of M. spicata; citronellol and geraniol by C. citratus; isopentyl alcohol and limonene by T. asperellum with increased peak area percentage and these compounds possessed antifungal properties. The vaporous action of isopentyl alcohol completely suppressed the mycelial growth of P. aphanidermatum, which is highly correlated to the T. asperellum extract on pathogenic growth. While the compounds, carvone, and citronellol showed the maximum inhibitory effect of 89.02 and 85.49 percent, respectively when used at 500 ppm and also altered the sporulation behavior of P. aphanidermatum.ConclusionResults showed that volatiles of M. spicata and T. asperellum have anti-oomycetes action on pathogenic growth leading to a distortion of sporulation of P. aphanidermatum. High antifungal properties make VOCs suitable for incorporation as a new integrated plant disease management programs.

Characteristics of microbial community in Linyi fermented pork sausage and their correlation with quality: effects of the single Lactobacillus starter

This study aimed to assess the effect of five Lactobacillus starters adding on the quality and bacterial diversity of Linyi fermented sausage (LFS). The relationships between the differentially abundant microorganisms and product quality were explored. The Lactobacillus bulgaricus (B), Lactobacillus casei (C), Lactobacillus reuteri (RE) and Lactobacillus rhamnosus (RH) were inoculated into the meat batter with single strains, and the commercial starter Lactiplantibacillus plantarum (P) was used as the control group. The results demonstrated that the B and C samples presented better fermentation characteristics (lower pH and aw), the most content of free amino acids, and significantly improved sausage sensory and texture properties. As for the volatile profile identified by headspace gas chromatography-ion mobility spectrometry, aldehydes were enriched in the B sample, which imparted a stronger fat, floral, honey-like fragrance. High-throughput sequencing showed that 11 bacteria genera were identified as differentially abundant. Spearman correlation revealed that excessive Klebsiella, Serratia and Hafnia-Obesumbacterium might not contribute to improving the quality of LFSs. Collectively, these findings are providing the theoretical guidance for the screening of functional starters.

Analytical method development, validation, and out-of-specification investigations for polyethylene glycol

This work was motivated by the United States Pharmacopeia monograph modernization initiative and European directorate for the quality of medicines and healthcare. An out-of-specification (OOS) occurrence prompted OOS investigations for the cGMP (cGMP refers to the Current Good Manufacturing Practice regulations enforced by the FDA) release testing of residual ethylene oxide in polyethylene glycol (PEG) according to the standards detailed within the United States Pharmacopeia/National Formulary (USP-NF) for polyethylene glycol, and the European Pharmacopoeia (Ph. Eur.) for macrogols. During the OOS root cause investigations, we observed a PEG degradant and identified it as methyl formate, which co-elutes with ethylene oxide using the GC (gas chromatography) methods published in current USP-NF and Ph. Eur. for PEGs. To address this, a novel method utilizing static headspace gas chromatography with flame ionization detection (HS-GC-FID) was developed to test various grades of PEGs for the presence of residual ethylene oxide, along with other process related impurities and degradation products. With this new method, ethylene oxide, a known genotoxic impurity and IARC (International Agency for Research on Cancer) Class 1 human carcinogen, can be well resolved from methyl formate, a newly identified and comparatively innocuous degradant derived from PEG. The currently available official compendial methods are unable to separate the specific impurities in PEGs. However, the new GC method presented in this paper has been shown to have a high and unique selectivity, allowing for baseline separations (chromatographic resolutions greater than 1.5) of all related impurities in PEGs, which is a challenging task. Additionally, this method has been found to be stability-indicating based on a forced degradation study. During stress stability study of PEGs involving acid, alkali, heat, light, and oxidation, some other PEG degradants, including formaldehyde, were identified. It is possible that formaldehyde undergoes a disproportionation reaction known as the Cannizzaro reaction, leading to the formation of formic acid and methanol. The formic acid then undergoes an esterification reaction with methanol to produce methyl formate. To the best of our knowledge, this is the first stability-indicating HS-GC-FID method that accomplishes this separation in a single run, and it was successfully validated as per ICH (the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use) guidelines. Therefore, this method is suitable for the conduct of cGMP batch release and stability testing of PEGs in regulated quality control (QC) laboratories.

Effect of headspace gas composition in kimchi packaging on the quality characteristics of kimchi.

The online version contains supplementary material available at 10.1007/s13197-023-05795-z.

Microwave heating and devolatilization characteristics of polyethylene particles in a fixed‐bed devolatilizer

AbstractA new method of microwave‐enhanced devolatilization has been proposed to solve the problem that volatiles of polyethylene particles are difficult to remove. Using water as microwave susceptor in a fixed‐bed devolatilizer, microwave heating characteristics were studied by optical fiber thermometry and infrared thermal imaging, and particle devolatilization characteristics were investigated by headspace gas chromatography. The results showed that bed temperature rose and particle devolatilization efficiency increased with heating time, moisture content, and input microwave power. The non‐uniform devolatilization at different positions existed due to the non‐uniform distribution of bed temperature in both radial and axial directions. The effective diffusion coefficient of volatiles under microwave irradiation increased with moisture content and input microwave power, and the microwave‐enhanced coefficient of water also increased with input microwave power. Microwave heating and devolatilization mechanism of moist polyethylene particles were proposed, in which the modes of mass and energy transfer were clarified. In view of the above, the feasibility of microwave‐enhanced polyethylene devolatilization has been confirmed.

The Potential of Soluble Gas Stabilization (SGS) Technology in a Simulated Post-Frying Cooling Step of Commercial Fish Cakes.

Soluble gas stabilization (SGS) technology is a novel way to increase the effectiveness of modified atmosphere (MA) packaging. However, SGS can be time-consuming and difficult to include in an existing process. This can be overcome by including CO2 in an existing processing step, such as the product's cooling step. A full factorial design was set up with SGS times (0.5, 1.0, and 2.0 h) and temperatures of fish cakes (chilled (0 °C) or during chilling (starting at 85 °C)) as factors. MA-packaged fish cakes were included as a control. The response was headspace gas composition at equilibrium. Headspace gas composition at equilibrium showed significantly (p < 0.05) less dissolved CO2 in hot fish cakes after 0.5 h than in cold cakes. Still, no significant differences were found between hot and cold at 1.0 and 2.0 h. Also, all SGS samples, regardless of time and temperature, had a higher content of CO2 compared to modified atmosphere packaging (MAP).

Analysis of Volatile Markers and Their Biotransformation in Raw Chicken during Staphylococcus aureus Early Contamination.

To address the potential risks to food safety, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) were used to analyze the volatile organic compounds (VOCs) generated from chilled chicken contaminated with Staphylococcus aureus during early storage. Together with the KEGG database, we analyzed differential metabolites and their possible biotransformation pathways. Orthogonal partial least squares discriminant analysis (OPLS-DA) was applied to characterize VOCs and identify biomarkers associated with the early stage of chicken meat contamination with S. aureus. The results showed 2,6,10,15-tetramethylheptadecane, ethyl acetate, hexanal, 2-methylbutanal, butan-2-one, 3-hydroxy-2-butanone, 3-methylbutanal, and cyclohexanone as characteristic biomarkers, and 1-octen-3-ol, tetradecane, 2-hexanol, 3-methyl-1-butanol, and ethyl 2-methylpropanoate as potential characteristic biomarkers. This provides a theoretical basis for the study of biomarkers of Staphylococcus aureus in poultry meat.