Extraction-gas Chromatography-mass Spectrometry Research Articles

Characterization of Aroma Active Compound Production during Kombucha Fermentation: Towards the Control of Sensory Profiles.

Since the sensorial profile is the cornerstone for the development of kombucha as a beverage with mass market appeal, advanced analytical tools are needed to gain a better understanding of the kinetics of aromatic compounds during the fermentation process to control the sensory profiles of the drink. The kinetics of volatile organic compounds (VOCs) was determined using stir bar sorptive extraction-gas chromatography-mass spectrometry, and odor-active compounds were considered to estimate consumer perception. A total of 87 VOCs were detected in kombucha during the fermentation stages. The synthesis of mainly phenethyl alcohol and isoamyl alcohol probably by Saccharomyces genus led to ester formation. Moreover, the terpene synthesis occurring at the beginning of fermentation (Δ-3-carene, α-phellandrene, γ-terpinene, m- and p-cymene) could be related to yeast activity as well. Principal component analysis identified classes that allowed the major variability explanation, which are carboxylic acids, alcohols, and terpenes. The aromatic analysis accounted for 17 aroma-active compounds. These changes in the evolution of VOCs led to flavor variations: from citrus-floral-sweet notes (geraniol and linalool domination), and fermentation brought intense citrus-herbal-lavender-bergamot notes (α-farnesene). Finally, sweet-floral-bready-honey notes dominated the kombucha flavor (2-phenylethanol). As this study allowed to estimate kombucha sensory profiles, an insight for the development of new drinks by controlling the fermentation process was suggested. Such a methodology should allow a better control and optimization of their sensory profile, which could in turn lead to greater consumer acceptance.

Graded Atmospheres of Volatile Pyrethroid Overlaid on Host Cues Can Be Established and Quantified Within a Novel Flight Chamber for Mosquito Behavior Studies.

Spatial repellents are emerging as a promising approach to reduce vector-disease burden; however, the evolution of genetically resistant mosquitoes decreases repellent efficacy. The development of flight chambers to investigate spatial repellent application techniques is vital for sustainable mosquito control. We present an air-dilution chamber as a novel bioassay to study mosquito flight behavior responses to chemical gradients of the volatile, pyrethroid transfluthrin (TF). Air dilution was used to simulate a larger environment of stable concentration gradients verified with carbon dioxide (CO2) which was homogenously delivered and measured across the chamber to achieve a 5× inlet/outlet [CO2] ratio with 0.17 m/s outlet velocity. Female Aedes (Ae.) aegypti (Diptera: Culicidae, Linnaeus, 1762) were exposed to volatilized TF paired with heat, CO2, and Biogents-Sweetscent host-cues. Tandem solvent extraction-gas chromatography-mass spectrometry (SE-GC-MS) was used to quantify air samples taken during TF emanations with a limit of detection (LOD) and quantification (LOQ) of 2 ± 1 and 5 ± 2 parts-per-trillion (ppt) TF, respectively. Homogenous air diluted emanation of the spatial repellent TF was at least twice that of the 5× CO2 gradient with the same air flow in the chamber. The airborne TF concentrations the mosquitoes were exposed to range from 1 to 170 ppt. Video recordings of mosquito behavior during host-cues exposure revealed increased inlet activity, while exposure to TF protected host resulted in decreased inlet activity over time with inlet-outlet mosquito positional variation. This novel flight chamber design can simulate 'long'-range exposure with simultaneous quantitation of airborne spatial repellent to understand dose-dependent effects on mosquito behavior.

An automated micro solid phase extraction gas chromatography–mass spectrometry (μSPE-GC–MS) detection method for geosmin and 2-methylisoborneol in drinking water

Geosmin and 2-methylisoborneol (2-MIB) are amongst the most common earthy and musty taste and odour (T&O) compounds found in drinking water. With low odour threshold detection limits below 10 ng L−1, and the complexity of raw water matrices, these two compounds provide a significant challenge for water companies globally. In this research, for the first time, a novel and fully automated micro-solid phase-extraction (μSPE) method coupled with gas chromatography (GC)–mass spectrometry (MS) has been developed for the detection of geosmin and 2-MIB for drinking water analysis. The new automated method described herein is environmentally friendly requiring low raw water sample volumes, of 25 mL, and only 50 μL of elution solvent. Our μSPE-GC–MS method exhibits excellent linearity for both compounds (R2 > 0.999) and low limits of detection of 2.0 ng L−1 and 4.3 ng L−1 for geosmin and 2-MIB, respectively. The method showed excellent recovery rates (95.1–100.1%) and good precision (RSD < 7%) in raw sample matrices. Our approach is fully automated onto a robotic workstation which can be readily integrated into a laboratory workflow for routine water analysis. Furthermore, the method has excellent potential to be incorporated within a portable system for onsite analysis.

Simultaneous determination of benzothiazoles, benzotriazoles, and benzotriazole UV absorbers by solid-phase extraction-gas chromatography-mass spectrometry.

Benzotriazoles (BTRs), benzothiazoles (BTHs), and benzotriazole ultraviolet absorbers (BUVs) are common products in plastic rubber and personal care products. Due to their toxicity and bioaccumulation, they have been identified as emerging contaminants (ECs) in the environment. Solid-phase microextraction (SPME) and solid-phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) were used for the enrichment and detection of the contaminants in seawater and sediment, respectively. The conditions of SPE and SPME were optimized in terms of material, temperature, time, pH, ionic strength, extraction solvent, and elution solvent. Although SPME requires a small sample volume, it is not reliable for the extraction efficiency and reproducibility of BTHs, BTRs, and BUVs in seawater. However, the precision of SPE-GC-MS for the determination of BTHs, BTRs, and BUVs was around 10%, with recoveries of 67.40-102.3% and 77.35-101.8% in seawater and sediment, respectively. The limits of detection of 14 contaminants in seawater and sediment were 0.03-0.47ng/L and 0.01-0.58ng/g, respectively. Secondly, BTHs, BTRs, and BUVs were detected with low ecological risk when SPE-GC-MS was applied to the analysis of seawater and sediment samples from the Yangtze estuary and its adjacent areas. The SPE-GC-MS was highly precise with lower detection limits relative to previous studies and thus was able to meet the requirements for the detection of BTHs, BTRs, and BUVs in seawater and sediments.

Determination of phthalic acid esters (PAEs) along with probabilistic health risk assessment in fruit juice samples in Tehran, Iran.

In the present study, magnetic solid phase extraction (MSPE) method and gas chromatography-mass spectrometry (GC/MS) technique were used to measure 6 PAE in fruit juice samples. The mean of total phthalic acid esters (ƩPAEs) in all samples was 3.55 ± 0.66µg/L. The mean concentration of DEHP (bis(2-ethylhexyl) phthalate) in samples was 0.82 ± 0.31µg/L, which was lower than the mentioned United States Environmental Protection Agency (USEPA) standard level in drinking water (6μg/L for DEHP). The pineapple juice samples (4.44 ± 0.57µg/L) and mango juice samples (2.77 ± 0. 1µg/L) had maximum and minimum mean levels of ƩPAEs, respectively. Also, results showed that brand B (3.76 ± 0.87µg/L) and samples in the time of expiration date (3.64 ± 0.72µg/L) had the highest PAE levels. The rank order Chronic Daily Intake (95%) values for adults were DEHP ([Formula: see text]) > butylbenzyl phthalates (BBP) ([Formula: see text]) > diethyl phthalate (DEP) ([Formula: see text]) and for children were DEHP ([Formula: see text]) > BBP (9.07E-04) > DEP ([Formula: see text]), which were below the tolerable daily intake (TDI) value. The noncancer risk of PAEs based on the target hazard quotient (THQ) was acceptable (< 1). The results exhibited that the Incremental Lifetime Cancer Risk (ILCR) was below the permissible limit (< [Formula: see text]). Therefore, the risk of carcinogenicity and noncarcinogenicity of PAEs in juices does not have adverse effects on human health.

Migration of volatile substances from recycled high density polyethylene to milk products

Plastic recycling is the main solution to reduce the plastic waste. High-density polyethylene has not been recycled yet successfully as food contact material due to the amount of chemicals present in post-consumer material together with its high chemical sorption capacity. The migration of two post-consumer recycled HDPE milk bottles were studied to both 50 % ethanol as food simulant and real food (one type skimmed milk and two plant base beverages (soy milk and horchata). Firstly, a headspace-solid phase extraction-gas chromatography mass spectrometry method was developed and optimized to analyze these milky samples. After exposure, 53 compounds were identified and among them several additives, NIAS such as 2,5-cyclohexadiene-1,4-dione, 2,6-bis(1,1-dimethylethyl), 2,4-di-tert-butylphenol and 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, degradation products of antioxidant compounds as well as several residues from cleaning products, detergents and flavoring agents were found. Finally, the risk assessment was applied and it was found that five compounds did not comply after migration to 50 % ethanol.

Tea pairings: Impact of aromatic congruence on acceptance and sweetness perception

Food pairing is a relevant tool for the food industry and for culinary professionals to develop successful flavor combinations and memorable experiences, but it could also be useful for encouraging consumers to adhere to a healthier diet. The general purpose of this study was to further investigate the perception of teas and butter cookies with and without aromatic congruence, deepening in sweetness perception. The experimental included: 1) a projective mapping test (30 semi-trained panelists) to group tea samples and choose representatives of each aromatic group; 2) the determination of the main volatile organic compounds using Solid Phase Micro Extraction-Gas Chromatography Mass Spectrometry (SPME-GC-MS) to prove the aromatic congruence of the designed tea-cookie pairings; 3) a consumer study (n = 89) to assess liking, sweetness perception, of the single samples and pairings, and the pairing principles of the congruent and non-congruent parings. Results of the projective mapping showed that the tea samples could be grouped into 3 main categories by their herbal, fruity-sweet, and brown-sweet notes, results also supported by the GCMS data. Harmony was positively correlated to liking, and Balance and Similarity seemed to be related to aromatic “congruence”, although all pairings were similarly liked. Sugar content was similar in all the cookie samples and pairings, but sweetness perception was significantly influenced by the aroma of the samples, being the samples and pairings made with spearmint the least sweet ones. Pairing a tea with sweet aromas with the spearmint cookie, independently of the kind of sweet aromatics (e.g.: coconut, almond, vanilla, fruity, tropical), seemed to slightly increase sweetness perception, although significant differences were not detected with other spearmint cookie pairings. Findings of the present research sum knowledge to the food pairing area, but further research is needed in recommending appropriate methodologies for pairing assessment, as well as the potential uses of driven pairings in specific food cultures.

Extraction and Identification of Volatile Compounds in Rosa laxa Retz var harputense T. Baytop "Kişmiri rose"

The gardening of ornamental plants comes back to ancient times (Urartians). Nowadays the gardening of ornamental plants is done worldwide as in the Van provinces of Türkiye. Old and traditional gardens can be seen in different regions of this province naturally. Among these plants, Rosa laxa Retzius var. harputense T. Baytop (Kişmiri rose), is an exotic plant coming from Central Asia. Kişmiri rose has semi-double and miniature flowers and blooms for about five months in the ecological conditions of Van. It has not only highly decorative but also has a light, pleasant, and enthusiastic fragrance. As far as we know there is no previously published on the volatile profile of Rosa laxa Retz var. harputense (Kişmiri rose). For this purpose, in this study, "Headspace Solid Phase Micro Extraction Gas Chromatography-Mass Spectrometry" (HS/SPME/GC/MS) was applied for the detection of volatile compounds of Kişmiri rose flowers. A total of 31 compounds of Kişmiri rose were identified and quantified using Gas Chromatography-Mass Spectrometry (GC/MS). Among these identified compounds, phenyl ethyl alcohol (26.59%), cis-3-hexenyl acetate (18.573%) was detected as the major ones. According to the obtained results, it is concluded that our species has also a Chinese origin.

Determination of 16 particle-phase polycyclic aromatic hydrocarbons in herbal incense by ultrasonic extraction-gas chromatography-mass spectrometry and analysis of emission characteristics

Polycyclic aromatic hydrocarbons (PAHs) have attracted global attention because they are carcinogens and mutagenic to humans. To date, more than 200 PAHs have been found. The United States Environmental Protection Agency (USEPA) has designated 16 PAH species as priority control pollutants due to their highly toxic substances. Herbal incense is frequently used in daily life. As a result, it is critical to investigate its impact on human health and environmental safety. However, research on particle-phase PAHs is very limited and inapplicable. The current research focuses mainly on bamboo incense, which has a simpler formula than herbal incense.In this study, the emission factor and emission characteristics of particle-phase PAHs from herbal incense were described. A method combining ultrasonic and gas chromatography-mass spectrometry (GC-MS) was developed for the simultaneous determination of 16 particle-phase PAHs of herbal incense. The settings for extraction solvent, ultrasonic time, and instrument analysis conditions were optimized. In the test chamber, samples were collected by burning 0.8 g of herbal incense. After combustion, PAHs adsorbing on the particles of herbal incense were collected on a quartz filter. The whole filter sample was sliced and extracted with n-hexane-dichloromethane (1∶1, v/v). A rotary evaporator was used to concentrate the extract. GC-MS was used to analyze the prepared sample. The internal standard method was used to perform quantitative analysis on the target compounds. The linearities of the 16 target PAHs were good between mass concentrations of 0.1-5.0 μg/mL, with correlation coefficients greater than 0.998. The method detection limits (MDLs) of the 16 PAHs ranged from 0.4 to 3.8 ng/g. The 0.625 μg/g and 1.25 μg/g spiked recoveries ranged from 77.4% to 99.5% and 82.0% to 101.3%, respectively. The relative standard deviations (RSDs) of the 16 PAHs were ranged from 0.7% to 7.2% (n=6). The emission factors of particle-phase PAHs from five different kinds of herbal incense ranged from 4.60 to 11.89 μg/g. The highest concentration of phenanthrene (Phe) was found in 16 particle-phase individual PAHs of herbal incense. Fluoranthene (Flu), pyrene (Pyr), chrysene (Chr) and anthracene (Ant) concentration were ranked after Phe. The sum of these five proportions was 73.00%-89.97%. The proportion of Phe in herbal incense particle-phase PAHs was significantly higher than that of other indoor combustion sources. As a result, Phe could be used to identify individual PAHs in the particle-phase of herbal incense. The particle-phase PAHs were mainly distributed on the 3-ring and 4-ring, with a sum of 83.84% to 96.31% on the 3-ring and 4-ring. The proportion of high-molecular weight PAHs in the samples ranged from 44.25% to 63.31%. The proportion of low-molecular weight PAHs in the samples ranged from 36.69% to 55.75%. The incense source could be distinguished from other indoor combustion sources by its distinctive Phe/Flu ratio. The established method has high sensitivity, simple operation, and requires fewer samples. This method is suitable for rapidly detecting PAHs in burning incense. At the same time, it provides scientific data for further studies on the distribution and health effects of particle-phase PAHs of herbal incense.

페놀 중독 사망사례

Phenol (also called carbolic acid) is a white or colorless crystalline solid, and it dissolves well in water and exists in a liquid state. Phenol has been mainly used as precursors for plastics, drugs and pesticides. In addition, phenol has been used as a preservative and a local anesthetic. Phenol causes severe irritation and corrosion on skin and other tissue by protein degeneration, and it may cause harmful effects on central nervous system and heart resulting in dysrhythmia, seizure, and death. Fatal cases by ingestion or intravenous injection of phenol for suicide were described in literatures, and there are many cases of death from accidental inhalation or absorption through the skin in workplace. In this study, we present two cases of death from phenol poisoning. Analysis of phenol in blood and tissues was performed by head space-solid phase micro extraction-gas chromatography-mass spectrometry method (HS-SPME-GC/MS). In one case, the concentration of phenol in heart and peripheral blood were 205.2 mg/L and 19.1 mg/L, respectively. In both cases, the concentration of phenol in liver and kidney tissue were 15.1-259.6 mg/kg and 45.8-38.5 mg/kg, respectively.

Pesticide residues in commonly consumed food from five localities of Burkina Faso: occurrence and health risk assessment.

Monitoring data for pesticides are generally scarce in many countries of the world, especially in developing countries. In Burkina Faso, there are few scientific data on the occurrence and concentrations of pesticide residues in staple foods found in local markets. Using QuEChERS extraction method and gas chromatography-mass spectrometry, samples of commonly eaten foods from five localities of Burkina Faso were evaluated by targeting more than 40 pesticides. It appears that 58.1% of all the collected samples exhibited at least one or more pesticide residues. Among those, 36.5% of the samples had at least one pesticide with a concentration above the maximum residue level (MRL) value. Unfortunately, no MRL data was available for dried fish which is a widely consumed food in this part of Africa. Simazine was found in tomatoes, pyrethroids in cereals, while dried fish contained most of the pesticides detected. The assessment of long-term health risks revealed that dieldrin quantified in dried fish showed more than 250% of acceptable daily intake which was then labelled as unacceptable high risk. For hazardous foods, more sampling should be carried out for a better assessment of the health risks involved.

Rapid Determination of Non-Steroidal Anti-Inflammatory Drugs in Urine Samples after In-Matrix Derivatization and Fabric Phase Sorptive Extraction-Gas Chromatography-Mass Spectrometry Analysis.

Fabric phase sorptive extraction (FPSE) has become a popular sorptive-based microextraction technique for the rapid analysis of a wide variety of analytes in complex matrices. The present study describes a simple and green analytical protocol based on in-matrix methyl chloroformate (MCF) derivatization of non-steroidal anti-inflammatory (NSAID) drugs in urine samples followed by FPSE and gas chromatography-mass spectrometry (GC-MS) analysis. Use of MCF as derivatizing reagent saves substantial amounts of time, reagent and energy, and can be directly performed in aqueous samples without any sample pre-treatment. The derivatized analytes were extracted using sol-gel Carbowax 20M coated FPSE membrane and eluted in 0.5 mL of MeOH for GC-MS analysis. A chemometric design of experiment-based approach was utilized comprising a Placket-Burman design (PBD) and central composite design (CCD) for screening and optimization of significant variables of derivatization and FPSE protocol, respectively. Under optimized conditions, the proposed FPSE-GC-MS method exhibited good linearity in the range of 0.1-10 µg mL-1 with coefficients of determination (R2) in the range of 0.998-0.999. The intra-day and inter-day precisions for the proposed method were lower than &lt;7% and &lt;10%, respectively. The developed method has been successfully applied to the determination of NSAIDs in urine samples of patients under their medication. Finally, the green character of the proposed method was evaluated using ComplexGAPI tool. The proposed method will pave the way for simper analysis of polar drugs by FPSE-GC-MS.

Determination of 31 Polycyclic Aromatic Hydrocarbons in Plant Leaves Using Internal Standard Method with Ultrasonic Extraction-Gas Chromatography-Mass Spectrometry.

The method for the determination of 16 priority polycyclic aromatic hydrocarbons (PAHs) in plant leaves has been studied extensively, yet the quantitativemethod for measuring non-priority PAHs in plant leaves is limited. A method for the simultaneous determination of 31 polycyclic aromatic hydrocarbons (PAHs) in plant leaves was established using an ultrasonic extraction-gas chromatography-mass spectrometry-internal standard method. The samples of plant leaves were extracted with ultrasonic extraction and purified with solid-phase extraction columns. The PAHs were separated by using gas chromatography-mass spectrometry equipped with a DB-EUPAH capillary column (20 m × 0.18 mm × 0.14 μm) with a selective ion monitoring (SIM) detection mode, and quantified with an internal standard. The method had good linearity in the range of 0.005~1.0 μg/mL with correlation coefficients greater than 0.99, and the method detection limit and maximum quantitative detection limit were in the ranges of 0.2~0.7 μg/kg and 0.8~2.8 μg/kg, respectively. The method was verified with spiked recovery experiments. The average spiked recovery ranged from 71.0% to 97.6% and relative standard deviations (n = 6) were less than 14%. Herein, we established a quantitativemethod for the simultaneous determination of priority and non-priority PAHs in plant leaves using GC-MS. The method is highly sensitive and qualitatively accurate, and it is suitable for the determination of PAHs in plant leaves.

Establishment and application of quantitative method for 22 organic acids in honey based on SPE-GC–MS

Honey, a natural healthy liquid bee product, is rich in amino acids, vitamins, and other essential nutrients. Different origin honeys also varied in organic acids. The objective of this study is to establish an efficient solid-phase extraction-gas chromatography–mass spectrometry (SPE-GC–MS) method to eliminate interference of sugar and other impurities for accurately estimating 22 organic acids in honey by optimizing extraction, purification, derivatization, and gas chromatography–mass spectrometry (GC–MS) analytical conditions. After being extracted, purified and derivatized, organic acids in honey were qualified and quantified by GC–MS. This method was evaluated experimentally, and the results showed that, within a certain concentration range, the standard curve linear relationship was satisfactory (R2 > 0.9942), and the target organic acid recovery rate was 86.74% ~ 118.68%. Besides, precision (relative standard deviation, RSD = 2.98% ~ 13.42%), detection limit (LOD = 0.002 ~ 0.2 mg kg−1), and quantification limit (LOQ = 0.008 ~ 0.5 mg kg−1) met the target requirements. Also, based on this analytical method, the organic acids in five types of honey (acacia, jujube, vitex, canola and linden honey) were estimated. Notably, they all contained 22 different kinds of organic acids, and significant differences (p < 0.05) in the organic acid content and composition among different honey varieties were observed. PCA analysis showed that the five honeys could be differentiated based on the content of 22 organic acids.

Development of an analytical method for the determination of sterol compounds in boars’ saliva

“Boar taint” compounds influence the sexual behavioral responses of sows and stimulate their reproduction. This paper reports a fast, easier, and a non-invasive analytical method for the analysis of three “boar taint” compounds in boar’ saliva samples: androstenone, androsten-3α-ol, and androsten-3β-ol. This method was developed and validated based on solid-phase extraction (SPE) and multidimensional gas chromatography-mass spectrometry (MDGC-MS). All the compounds were detected without derivatization. This method affords good reproducibility (4%–8%), accuracy (80%–105%), precision (5.5%–9.1%), linearity (R2 = 0.98–0.99), and lower limits of quantitation (LLOQ) (0.1–0.2 μg/L). Although the presence of these compounds in saliva has been known for a long time, no simple and easy analytical method has been developed.

Determination of Volatile Metabolites in Vinegar by Stir Bar Sorptive Extraction-Gas Chromatography-Mass Spectrometry (SBSE-GC-MS).

Stir bar sorptive extraction (SBSE) is a rapid, sensitive, precise, and environmentally friendly extraction technique that, coupled to gas chromatography-mass spectrometry detection (GC-MS), enables the simple determination of volatile organic compounds in liquid samples. The present protocol describes the procedure for the determination of volatile compounds in vinegar by means of SBSE-GC-MS.

Multi-omics and enzyme activity analysis of flavour substances formation: Major metabolic pathways alteration during Congou black tea processing

To comprehensively analyse flavour substance formation in Congou black tea, dynamic changes in non-volatile and volatile compositions and enzymatic activity were analysed. In total, 107 non-volatile and 222 volatile compositions were identified via ultra-high performance liquid chromatography coupled with quadrupole-exactive mass spectrometry (UHPLC-Q-Exactive/MS) and stir bar sorptive extraction-gas chromatography-mass spectrometry (SBSE-GC–MS), and eight metabolic pathways were explored during tea processing. Significant variations in metabolites were observed during processing (P < 0.05), especially in the fermentation stage, including high accumulation of taste and colour substances due to decreased flavonoid synthase activity and elevated oxidase activity. Correlation analysis clarified that the mutual transformation between non-volatile and volatile substances occurs in certain types of processing, including amino acids, amino acid-derived volatiles (AADVs), glycosidically bound volatiles (GBVs), and volatile terpenoids (VTs). Our study provides a detailed overview of the dynamic changes of in flavour substrates and key enzyme activities during Congou black tea processing.

Effects of Combined Garcinia kola and Kigelia africana on Insulin and Paraoxonase 1 (PON1) Levels in Type 2 Diabetic Rats.

Individual extracts of Garcinia kola and Kigelia africana have been shown to have therapeutic effects against a variety of variables linked to the development of diabetes mellitus. However, there is still a lack of information about the combined effects of these extracts on Insulin and Paraoxonase 1 (PON-1) in Streptozotocin-Nicotinamide-induced type-2 diabetic Wistar rats. Forty-two young male rats (180-200g) were randomly divided into six groups (n = 7/group). Diabetes was intraperitoneally induced with 110 mg/kg of nicotinamide constituted in distilled water and fifteen minutes later with 65 mg/kg of streptozocin freshly prepared in 0.1M citrate buffer (pH of 4.5) and treated for six weeks as follows: the control rats received either 0.9% normal saline (NS) or 250 mg/kg extract by gavage. The remaining animals were diabetes induced and subsequently treated with either NS, graded doses of the extract (250 mg/kg and 500 mg/kg), or 5 mg/kg Glibenclamide + 100mg/kg Metformin. Gas chromatography-mass spectrometry (GCMS) of the combined extracts was also analyzed to identify the bioactive compounds present in it. Insulin, PON-1 levels, lipid profiles, and atherogenic index were assessed. Our findings show that Insulin and PON-1 levels in the plasma of diabetic rats treated with the combined extracts were significantly increased when compared to the control rats. Moreover, the GCMS of the extract shows the presence of both monounsaturated (oleic acid) and polyunsaturated (linoleic acid) fatty acids. The current findings suggest that the extract may help improve glucose homeostasis and prevent atherosclerosis through the established mechanism of the identified bioactive compounds.

Screening of mixed-species starter cultures for increasing flavour during fermentation of milk

Flavour is an important factor determining the quality of fermented dairy products. Three L.delbrueckii subsp. bulgaricus isolates and five Streptococcus thermophilus isolates with good fermentation characteristics were selected for evaluation as starter cultures when used in ten different combinations, and in comparison with a commercial starter. Using solid phase micro extraction-gas chromatography-mass spectrometry (SPME-GC-MS) analysis, a total of 55 volatile compounds and nine odour-active compounds were detected in milk fermented by mixed-species starter cultures C5 (L. delbrueckii subsp. bulgaricus IMAU62081: S. thermophilus IMAU40133). The results from partial least squares-discriminant analysis (PLS-DA), electronic nose (E-nose) analysis and sensory evaluation indicated that flavor composition and content of fermentation samples from the C5 mixture were closer to the commercial control than the other mixtures. These results help understand how volatile flavour compounds in yoghurt are affected by the starter culture; this will be useful in the development of value-added fermented dairy products.

Effect of the type of acetic fermentation process on the chemical composition of prickly pear vinegar (Opuntia ficus-indica).

In several countries, the cactus plant (Opuntia ficus-indica (L). Mill.) has received renewed attention because of its ecological, socio-economic and environmental role. In this study, prickly pear vinegar was produced employing two types of acetification processes: surface and submerged culture. Both acetification processes were performed at different temperatures (30, 37, 40 °C) by using two different species of thermotolerant acetic acid bacteria (Acetobacter malorum and Gluconobacter oxydans). Polyphenols and volatile compounds analyzed by ultra-performance liquid chromatography with diode array detection and stir bar sorptive extraction-gas chromatography-mass spectrometry, respectively, were considered as the main variables to determine the effect of the acetification process on the quality of the vinegar. As a result, 15 polyphenols and 70 volatile compounds were identified and quantified in the vinegar samples produced by both acetification processes. The results showed that the surface acetification method led to an increase in the concentration of phenolic components, which was higher than that in the submerged process. However, a significant increase in volatile compounds predominated by esters and acids was observed when submerged culture acetification was employed, whereas alcohols were predominant in surface culture vinegars. Moreover, multivariate statistical analysis showed that the components that mostly contributed to the differentiation between all vinegar samples were the volatile compounds. It has been proved that prickly pear vinegar could be successfully produced at higher temperatures than usual, by employing thermotolerant bacteria, and that the type of acetification method significantly affects the final quality of the vinegar produced. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.