Hexanoate Research Articles

Hexanoic acid production from anaerobic fermentation of Chinese cabbage waste with exogenous lactic acid as electron donor

The lack of electron donors is one of the key factors hindering hexanoic acid production from anaerobic fermentation. In this study, three different types of lactic acids were supplemented as exogenous electron donors to the anaerobic fermentation system of Chinese cabbage waste (CCW). The yields of hexanoic acid in the reactors supplemented with CCW lactic acid pre-fermentation broth (PFB), lactic acid diluent (LAD) and chemical lactic acid (LA) were 6996.8 mg COD/L, 4534.8 mg COD/L and 6777.1 mg COD/L, respectively. Compared with the reactor supplemented with LA, the electron efficiency of hexanoic acid in reactor supplemented with PFB increased by 188 %. Supplementing PFB shifted the microbial communities towards a direction favorable to hydrolysis and chain elongation, thereby facilitating the synthesis of hexanoic acid.

Trypanosoma cruzi infection enhances olfactory response in Triatoma pallidipennis Stål (Hemiptera: Triatominae) to compounds potentially useful for insect control.

In Mexico, Triatoma pallidipennis is a major vector of Trypanosoma cruzi, the causative agent of Chagas disease. Current efforts are focused on developing attractants to control these vectors, using volatile substances derived from vertebrate hosts or compounds known to attract hematophagous insects. However, the efficacy of these compounds in attracting parasite-infected triatomines remains to be evaluated. In this study, we assessed the attractant activity of octenol (1-octen-3-ol), nonanal and a mixture of odorants consisting of ammonium hydroxide, lactic acid and hexanoic acid (in a ratio of 1:0.2:0.4 respectively), at concentrations of 1, 10 and 100 ng on the N3, N4 and N5 nymphal stages of T. pallidipennis, both infected and non-infected with T. cruzi. We also evaluated the synergistic effect of the most effective compounds and doses. All experiments were performed in a laboratory using a Y-type glass olfactometer. We found that both infected and non-infected N3 and N4 nymphs were attracted to low doses of octenol, nonanal and the odorant mixture. Particularly noteworthy was the synergistic effect observed between the odorant mixture and nonanal, which significantly increased attraction of T. cruzi-infected individuals. These findings contribute to the development of baited traps utilising these compounds for monitoring triatomines in epidemiological studies or for mass trapping to control these vectors.

Caproic acid production from short-chained carboxylic acids produced by arrested anaerobic digestion of green waste: Development and optimization of a mixed caproic acid producing culture

Caproic acid is an important compound for producing a variety of chemicals and a potential precursor for Sustainable Aviation Fuels (SAF). This study aimed at developing a stable mixed culture producing caproic acid using short-chain carboxylic acids (SCCAs) derived from arrested anaerobic digestion (AAD) of green waste and optimizing chain elongation (CE) conditions. The results showed that the mixed culture was dominated by Clostridium sensu stricto 12 (53.09 %), optimally producing caproic acid at 37 °C, pH 7.20, with a 15 % inoculum concentration. Under these conditions, 75.59 % of the consumed electrons contributed to caproic acid formation. Gradual ethanol feeding in bioreactor experiments resulted in caproic acid titer of 13.36 g/L, with carbon conversion efficiency (CCE) of 81.91 % and electron transfer efficiency (ETE) of 76.39 %, surpassing batch experiments without gradual ethanol addition. These findings demonstrate that the effectiveness of a mixed culture can be improved, resulting in increased caproic acid production.

Diethyl aminoethyl hexanoate ameliorates salt tolerance associated with ion transport, osmotic adjustment, and metabolite reprograming in white clover

BackgroundSoil salinization is a serious environmental hazard, limiting plant growth and production in different agro-ecological zones worldwide. Diethyl aminoethyl hexanoate (DA-6) as an essential plant growth regulator (PGR) exhibits a beneficial role in improving crop growth and stress tolerance. However, the DA-6-regulated effect and mechanism of salt tolerance in plants are still not fully understood. The objective of current study was to disclose salt tolerance induced by DA-6 in relation to changes in water and redox balance, photosynthetic function, ionic homeostasis, and organic metabolites reprogramming in white clover (Trifolium repens).ResultsA prolonged duration of salt stress caused water loss, impaired photosynthetic function, and oxidative injury to plants. However, foliar application of DA-6 significantly improved osmotic adjustment (OA), photochemical efficiency, and cell membrane stability under salt stress. In addition, high salinity induced massive accumulation of sodium (Na), but decreased accumulation of potassium (K) in leaves and roots of all plants. DA-6-treated plants demonstrated significantly higher transcript levels of genes involved in uptake and transport of Na and K such as VP1, HKT8, SOS1, NHX2, NHX6, and SKOR in leaves as well as VP1, HKT1, HKT8, H+-ATPase, TPK5, SOS1, NHX2, and SKOR in roots. Metabolomics analysis further illustrated that DA-6 primarily induced the accumulation of glucuronic acid, hexanoic acid, linolenic acid, arachidonic acid, inosose, erythrulose, galactopyranose, talopyranose, urea, 1-monopalmitin, glycerol monostearate, campesterol, stigmasterol, and alanine.ConclusionsThe DA-6 significantly up-regulated transcript levels of multiple genes associated with increased Na+ compartmentalization in vacuoles and Na+ sequestration in roots to reduce Na+ transport to photosynthetic organs, thereby maintaining Na+ homeostasis under salt stress. The accumulation of many organic metabolites induced by the DA-6 could be attributed to enhanced cell wall and membrane structural stability and functionality, OA, antioxidant defense, and downstream signal transduction in leaves under salt stress. The present study provides a deep insight about the synergistic role of DA-6 in salt tolerance of white clover.

Blackcurrant Anthocyanins Attenuate Estrogen -Deficiency-Induced Bone Loss through Modulating Microbial-Derived Short-Chain Carboxylic Acids and Phytoestrogen Metabolites in Peri- and Early Postmenopausal Women.

The present study aimed to assess the effects of blackcurrant (BC) anthocyanins on concentrations of microbial-derived short-chain carboxylic acids (SCCAs) and metabolites of phytoestrogens. We then examined their associations with six-month changes in whole-body bone mineral density (BMD) and biomarkers of bone metabolism. Fecal and blood samples from a pilot randomized controlled trial were collected and analyzed from 37 eligible peri- and early postmenopausal women aged 45-60 years who were randomized into one of three treatment groups consuming one placebo capsule (control), 392 mg BC (low BC) or 784 mg BC (high BC) daily for six months. Significant differences were observed between groups at baseline in acetic, propionic, valeric, caproic and heptanoic acids (p < 0.05). Isobutyric acid significantly decreased from baseline (0 months) to six months in the control group (p < 0.05) and the high BC group had a significantly greater concentration than the control group at six months (p < 0.05). Butyric acid was significantly greater in the high BC group than low BC at six months (p < 0.05). Six-month changes in caproic and isobutyric acids showed weak correlations with changes in whole-body BMD (r = 0.3519, p < 0.05 and r = 0.3465, p < 0.05, respectively). Isovaleric and valeric acids displayed weak correlations with BALP (r = 0.3361, p < 0.05) and OPG (r = 0.3593, p < 0.05), respectively. Enterodiol was positively correlated with BALP (r = 0.6056, p < 0.01) while enterolactone was positively correlated with osteocalcin (r = 0.5902, p < 0.001) and negatively correlated with sclerostin (r = -0.3485, p < 0.05). The results suggest that BC may be a potential dietary agent to reduce postmenopausal bone loss through modulating microbially-derived SCCAs and phytoestrogen metabolites.

Characterization of Changes in Ripening Process of Volatile Apple Compounds Based on HS-SPME-GC-MS Analysis

The aim of this study was to identify the aromatic compounds present in different apple varieties and to gain insights into the changes in the aromatic compounds during ripening. Three apple varieties (“Red Astrachan”, “Ning Qiu”, and “Golden Delicious”) at different stages of ripening were selected for this study; their peel and pulp were analyzed via headspace solid-phase microextraction (HS-SPME)–gas chromatography–mass spectrometry (HS-SPME-GC-MS), and 30 volatile compounds were identified. The samples’ differences were analyzed using heat map cluster analysis, principal component analysis (PCA), and an independent samples t-test. The results showed that the content of aromatic compounds in the peel was higher than that in the pulp. The relative content of esters in the aromatic compounds of the three apple varieties followed the order of pulp &gt; peel and “Ning Qiu” &gt; “Golden Delicious” &gt; “Red Astrachan”. This suggests that “Ning Qiu” combines the advantages of its parents in terms of its aroma content. The highest concentrations of aroma compounds in “Red Astrachan” and “Ning Qiu” accumulate before the ripening stage, and care should be taken to choose an appropriate harvesting time according to the different needs during production. The main compounds of “Red Astrachan” are aldehydes and C8 esters, while those of “Ning Qiu” and “Golden Delicious” are alkenes and esters. After analyzing the relative odor activity values (rOAVs) of key volatile compounds and their aroma descriptors during the harvest period, acetic acid pentyl ester, butanoic acid hexyl ester, hexanoic acid hexyl ester, and 2-ethyl-1-Hexanol were found to contribute the most to the overall flavor of the peel and pulp. “Ning Qiu” combines the parental advantages of the concentrated peel of “Red Astrachan” and the astringent pulp of “Golden Delicious”, with compounds in its composition that give a pleasing aroma. Mature “Ning Qiu” fruits have a more intense aroma and fruity flavor. The development of flavor-specific varieties has provided the theoretical basis for future research in molecular hybridization, molecular-assisted breeding, and the molecular biology of apple flavor synthesis and metabolism.

Identification of Volatile Organic Compounds and Analysis of Aroma Characteristics in Ten Pear Syrups.

Aroma in food plays an important role in food perception and acceptance, which depends on various mixtures of volatile organic compounds (VOCs). Moreover, VOCs are of great significance for aroma identification. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) technology was used to determine the VOCs in 10 pear syrups. A total of 127 VOCs were quantitatively determined, including 9 common VOCs and 46 characteristic VOCs of 10 pear syrups. The pear syrups were divided into three categories by cluster analysis, and thirty-eight differential VOCs were obtained using orthogonal partial least squares discrimination analysis (OPLS-DA) and fourteen key VOCs were selected by odor activity value (OAV). It was revealed that the key and common aroma components of pear syrups were butanoic acid, methyl ester, 2-methyl-, methyl ester and Hexanoic acid, and ethyl ester. The characteristic and differential VOCs were 10-Undecen-1-ol, Hexadecanal, n-Propylacetate, Cyclohexanol, 5-methyl-2-(1-methylethyl)-, (1S,2R,5S)-, Methional, Disulfide, dimethyl, 8-Nonenoic acid, ethyl ester, Naphthalene, 1,2-dihydro-1,1,6-trimethyl-, 3H-Purin-6-amine, N,N,3-trimethyl-, 2-Octanol,2,6-dimethyl-, Furyl hydroxymethyl ketone, Heptane, 2,2,4,6,6-pentamethyl-, and Butanoic acid,2-methyl-,methyl ester. The above results showed that different pear syrups had rich diversity in aroma compounds, with some components being shared among them while others are exclusive to specific syrups.

Caproiciproducens converts lactic acid into caproic acid during Chinese strong-flavor Baijiu brewing

Strong-flavor Baijiu, a type of Chinese liquor, is produced through anaerobic solid-state fermentation in a sealed mud pit. Ethyl caproate, the characteristic flavor compound of strong-flavor Baijiu, is influenced by caproic acid-producing bacteria in the pit mud. To better understand the formation of caproic acid, this study investigated the microbial composition and physicochemical parameters of pit mud from different layers (top, middle, and bottom) in Hubei and Sichuan provinces, China. The results revealed that Caproiciproducens plays a key role in caproic acid production by using lactic acid as a substrate, with its abundance increasing with the depth of the pit mud. A strain Caproiciproducens sp. R1, isolated from the pit mud, was shown to produce caproic acid from lactic acid within an initial pH range of 5.5–9.0 and lactic acid concentrations of 1 %–5 % (m/v). In addition, inoculation of strain R1 into Huangshui (a lactic acid-rich liquid from Baijiu production) resulted in 40.72 mM caproic acid production. This study demonstrates that Caproiciproducens plays a crucial role in caproic acid production from lactic acid during the fermentation process of strong-flavor Baijiu.

Comparative Analysis of Microbial Diversity and Metabolic Profiles during the Spontaneous Fermentation of Jerusalem Artichoke (Helianthus tuberosus L.) Juice.

Jerusalem artichoke juice is valued for its nutritional content and health benefits. Spontaneous fermentation enhances its flavor, quality, and functional components through microbial metabolic activities. This study used high-throughput sequencing to analyze microbial community changes, and LC-MS and GC-MS to detect secondary metabolites and flavor compounds during fermentation. During natural fermentation, beneficial bacteria like Lactobacillus and Pediococcus increased, promoting lactic acid production and inhibiting harmful bacteria, while environmental bacteria decreased. Similarly, fungi shifted from environmental types like Geosmithia and Alternaria to fermentation-associated Pichia and Penicillium. A total of 1666 secondary metabolites were identified, with 595 upregulated and 497 downregulated. Key metabolic pathways included phenylpropanoid biosynthesis, with significant increases in phenylalanine, tryptophan, and related metabolites. Lipid and nucleotide metabolism also showed significant changes. Flavor compounds, including 134 identified alcohols, esters, acids, and ketones, mostly increased in content after fermentation. Notable increases were seen in Phenylethyl Alcohol, Ethyl Benzenepropanoate, 3-Methylbutyl Butanoate, Ethyl 4-Methylpentanoate, 5-Ethyl-3-Hydroxy-4-Methyl-2(5H)-Furanone, Ethyl Decanoate, Hexanoic Acid, and 1-Octanol. γ-aminobutyric acid (GABA) and other functional components enhanced the health value of the juice. This study provides insights into microbial and metabolic changes during fermentation, aiding in optimizing processes and improving the quality of fermented Jerusalem artichoke juice for functional food development.

B-172 Correlation of Microbiome Sequencing Data and Quantified Short-Chain Fatty Acids by LC-MS/MS in IBD and Non-IBD Stool Samples

Abstract Background SCFAs are the primary metabolites produced by bacterial fermentation of dietary fiber and undigested proteins. They play a crucial role in various metabolic pathways, such as regulating the host’s energy balance and anti-inflammatory processes. The most studied SCFAs are acetic acid, propionic acid and butyric acid, with an approximate molecular ratio of 60:20:20 in healthy adults. A significantly different distribution may indicate a bacterial dysbiosis. While most SCFAs have a positive impact on the host’s health, the impact of branched short-chain fatty acids (bSCFAs), such as isobutyric acid and isovaleric acid, are less well-known. In order to evaluate whether the determination of a broader SCFA panel holds additional diagnostic value, we have developed a sensitive and robust LC-MS/MS method to determine 11 C2 - C7 SCFAs in human fecal samples. Methods The LC-MS/MS method includes acetic acid (AA), propionic acid (PA), butyric acid (BA), valeric acid (VA), caproic acid (CA) and heptanoic acid (HA), as well as the isomers isobutyric acid (iBA), 2-methylbutyric acid (2-MBA), isovaleric acid (iVA), isocaproic acid (iCA) and 2-methylhexanoic acid (2-MHA). After suspending the stool samples in a stabilizing buffer, the tubes were centrifuged and 25 µl of the supernatant was mixed with an internal standard solution (10 isotopically labeled internal standards) and subsequently derivatized. After one hour, the reaction was quenched and samples were injected into an ACQUITY UPLC H-Class (Waters) with an injection cycle of 9.5 min. Analytes were measured in positive mode by ESI-MS/MS on a Xevo TQ-MS (Waters). For quantification, six calibrators and three controls covering the anticipated physiological ranges were used. Results Microbiome sequencing data identified a total of 193 species, most of which belong to the Firmicutes phylum. Next, Actinobacteria and Proteobacteria are in descending order of abundance. In our IBD samples, we see a significant dysbiosis of these ratios and orders in comparison to the screening patients. E.g. in one sample, no Bacteroidetes were found, but a high amount of Actinobacteria (40 %) were sequenced. Corresponding SCFA data detected an AA:PA:BA ratio of 76:11:10, as well as no VA, iCA, CA, 2-MHA and HA, whereas SCFA data from most screening patients showed an AA:PA:BA ratio of 60:20:20 (± 10:10:10). Conclusions After a fast and simple sample preparation and derivatization, the LC MS/MS method allows robust and sensitive measurement of all presented SCFAs from human feces samples. The preliminary analysis of the combined microbiome and SCFA data showed that the detected AA:PA:BA ratio difference could be a valid indicator for a dysbiosis or an altered microbiome, corroborating data from previous studies. While we could detect differences on bSCFAs and longer SCFAs between IBD and non-IBD patient samples in this pilot study, larger patient and control cohorts are needed in order to substantiate our initial promising findings and finally allow a robust evaluation of these parameters as diagnostic tool to monitor and determine the state of the patient microbiome.

Flavor properties of post-heated fermented milk revealed by a comprehensive analysis based on volatile and non-volatile metabolites and sensory evaluation

Existing research on the post-heating processing of fermented milk has primarily focused on single post-heating treatments and the texture, while research on how changes in metabolites during different post-heating treatments affect flavor and sensory properties is limited. This study investigates the changes in volatile metabolites in fermented milk treated at different post-heating temperatures to determine the characteristic aroma types and analyzes the changes in non-volatile metabolites associated with aroma-active compounds or their precursors to clarify the causes of the altered flavor and sensory properties. The results showed that in the 65°C and 75°C treatments, 63 volatile compounds were produced by Strecker degradation, lipid oxidation and esterification to produce ketones and aldehydes. Significantly higher odor activity values for 2,3-butanedione, hexanoic acid, and esters and significantly lower odor activity values for 2-heptanone enhanced the frankincense odors and creaminess of the post-heated fermented milk. With temperatures increasing to 95°C, the increased ketones were primarily 2-heptanone, 2-nonanone, and 2-undecanone that originated from the oxidative decomposition of unsaturated phospholipids at high temperatures. The Maillard reaction of dipeptides produces nitrogenous heterocycles that trigger a caramelized flavor, while organic acids interact with proteins to form complexes that produce astringent flavors. These increase the oxidative off-flavors and reduce the overall palatability. These findings provide a scientific basis for optimizing the post-heating temperature process of fermented milk.

Integrative microbiomics, proteomics and lipidomics studies unraveled the preventive mechanism of Shouhui Tongbian Capsules on cerebral ischemic stroke injury

Ethnopharmacological relevanceCerebral ischemic stroke (CIS) is one of the most important factors leading to death and disability, which seriously threaten the survival and health of patients. The intentional flora and its derived metabolites are demonstrated to play vital roles in the physiology and onset of CIS. Shouhui Tongbian Capsules (SHTB), a Traditional Chinese Medicine, could regulate gut microbiota and metabolites. Study has found that SHTB has protective effect on CIS, but the mechanism is still unclear. Aim of studyThis study was designed to evaluate the preventive effects and the mechanism of SHTB on CIS injury. Materials and methodsThe rats were pretreated with SHTB for 5 days, then the middle cerebral artery occlusion/reperfusion (MCAO/R) was established. Neurological deficit score, TTC staining, brain water content, H&E and Nissl staining were preformed to evaluate the preventive effects of SHTB on CIS. The Occludin and ZO-1 were analyzed to evaluate the blood-brain barrier (BBB). 16S rDNA sequencing and LC-ESI-MS/MS-based metabolomics profiling were performed to analyze the gut microbiota composition and short chain fatty acids (SCFAs) profile in gut. Serum lipopolysaccharide specific IgA antibody (LPS-SIgA) and diamine oxidase (DAO), as well as colon Claudin 5 and ZO-1 were analyzed to evaluate the intestinal barrier. Proteomics was used to evaluated the proteins profile in brain. Lipidomics were used to evaluate the brain SCFAs as well as medium and long chain fatty acids (MCFAs and LCFAs). Malondialdehyde (MDA), Total Superoxide dismutase (T-SOD), Glutathione (GSH), Glutathione peroxidase (GSH-Px), Catalase (CAT) and reactive oxygen species (ROS) were assayed to evaluate the oxidative stress in brain. Western blot was performed to evaluate the expression of PPARγ, Nrf2, SLC3A2, SCL7A11, GPX4, ACSL4 and LOX. ResultsSHTB prevented rats from MCAO/R injury, which was confirmed by lower cerebral infarct rate, brain water content, neurological deficit score and nissl body loss, and improved brain pathology. Meanwhile, SHTB upregulated the expression of ZO-1 and Occludin to maintain the integrity of BBB. 16S rDNA sequencing and LC-ESI-MS/MS-based targeted metabolomics found that SHTB increased the abundance of gut microbiota, regulated the numbers of intestinal bacteria to increase the production of Acetic acid, Propionic acid, and Butyric acid, as well as decrease the production of Valeric acid and Hexanoic acid in the gut. Meanwhile, SHTB improved the intestinal barrier by upregulating the protein levels of Claudin 5 and ZO-1, which was confirmed by low concentrations of LPS-SIgA and DAO in serum. Multi omics and spearman correlation analysis indicated that SHTB regulated the abundance of Escherichia-Shigella and Lactobacillus to increase Acetic acid, Propionic acid, and Butyric acid to induce the expression of PPARγ, thereby regulating fatty acid metabolism and degradation, improving lipid metabolism disorders, downregulating lipid oxidative stress, inhibiting ferroptosis, and alleviating brain injury. ConclusionThis study confirmed that SHTB improved the disturbance of fatty acid metabolism in brain tissue by regulating gut microbiota and the production of fecal SCFAs to inhibit ferroptosis caused by lipid oxidative stress and prevent CIS injury, which provided a potential candidate drug for the prevention of CIS.

Molecular Targets of Valeric Acid: A Bioactive Natural Product for Endocrine, Metabolic, and Immunological Disorders.

Postbiotics produced by gut microbiota have exhibited diverse pharmacological activities. Valeric acid, a postbiotic material produced by gut microbiota and some plant species like valerian, has been explored to have diverse pharmacological activities. This narrative review aims to summarise the beneficial role of valeric acid for different health conditions along with its underlying mechanism. In order to get ample scientific evidence, various databases like Science Direct, PubMed, Scopus, Google Scholar and Google were exhaustively explored to collect relevant information. Collected data were arranged and analyzed to reach meaningful a conclusion regarding the bioactivity profiling of valeric acid, its mechanism, and future prospects. Valeric acid belongs to short-chain fatty acids (SCFAs) compounds like acetate, propionate, butyrate, pentanoic (valeric) acid, and hexanoic (caproic) acid. Valeric acid has been identified as one of the potent histone deacetylase (HDAC) inhibitors. In different preclinical in -vitro and in-vivo studies, valeric acid has been found to have anti-cancer, anti-diabetic, antihypertensive, anti-inflammatory, and immunomodulatory activity and affects molecular pathways of different diseases like Alzheimer's, Parkinson's, and epilepsy. These findings highlight the role of valeric acid as a potential novel therapeutic agent for endocrine, metabolic and immunity-related health conditions, and it must be tested under clinical conditions to develop as a promising drug.

Enhancement of PFAS stress tolerance and wastewater treatment efficiency by arbuscular mycorrhizal fungi in constructed wetlands

This study aims to explore the effects of arbuscular mycorrhizal fungi (AMF) on the growth of Iris pseudacorus L. and treatment efficacy in constructed wetlands (CWs) subjected to stress from per-and poly-fluoroalkyl substances (PFASs). The findings reveal that PFASs exposure induces oxidative damage and inhibits the growth of I. pseudacorus. However, AMF symbiosis enhances plant tolerance to PFAS stress by modulating oxidative responses. AMF treatment not only promoted plant growth but also improved photosynthetic efficiency under PFAS exposure. Compared to non-AMF treatment, those with AMF treatment exhibited significantly increased levels of peroxidases and antioxidant enzymes, including peroxidase and superoxide dismutase, along with a notable reduction in lipid peroxidation. Additionally, AM symbiosis markedly enhanced the efficacy of CWs in the remediation of wastewater under PFASs-induced stress, with removal efficiencies for COD, TP, TN, and NH4+-N increasing by 19–34%, 67–180%, 106–137%, and 25–95%, respectively, compared to the AMF- treatments. In addition, the metabolic pathways of PFASs appeared to be influenced by their carbon chain length, with long-chain PFASs like perfluorooctanoic acid (PFOA) and perfluoro anionic acid (PFNA) exhibiting more complex pathways compared to short-chain PFASs such as perfluoro acetic acid (PFPeA), and perfluoro hexanoic acid (PFHpA). These results suggest that AMF-plant symbiosis can enhance plant resilience against PFAS-induced stress and improve the pollutant removal efficiency of CWs. This study highlights the significant potential of AMF in enhancing environmental remediation strategies, providing new insights for the more effective management of PFAS-contaminated ecosystems.

Aroma-active compounds in Russian sturgeon (Acipenser gueldenstaedtii) raised in recirculating aquaculture systems

The rearing system affects the nutritional and sensorial qualities of the Russian sturgeon (Acipenser gueldenstaedtii), a niche yet commercially valuable aquaculture species for caviar production. In the present work, we aimed to comprehensively characterize the odorant composition of fillets from Russian sturgeon raised in a recirculating aquaculture system (RAS) and discuss potential sources and formation pathways. A total of 114 odorants were detected through the application of combined sensory-instrumental analyses, of which 88 were successfully identified and 20 substances were found to be among the most potent odor constituents. The most dominant odorants were assigned to several specific substance classes, including aldehydes, alcohols, terpenes, ketones, organic acids, lactones, heterocycles, aromatic hydrocarbons, and sulfur-containing aldehydes. The compounds (E)-hex-2-enal, (Z)-hept-4-enal, cuminaldehyde, non-3-yn-1-ol, 3-carene, 2-methylisoborneol, geosmin, oct-1-en-3-one, nonan-3-one, (Z)-1,5-octadien-3-one, octane-2,3-dione, nonan-2-one, hexanoic acid, γ-crotonolactone, γ-octalactone, 2-acetyl-thiazoline, methional, and (2E,4Z,7Z)-trideca-2,4,7-trienal had high flavor dilution factors and are described for the first time as potent odor-active compounds associated with the Russian sturgeon. Overall, oct-1-en-3-one, (Z)-1,5-octadien-3-one, octane-2,3-dione, nonan-2-one, 2-methylisoborneol, and hexanoic acid had the highest flavor dilution factors. This study offers a basis for future development in the sturgeon RAS industry from the perspective of flavor characterization by providing deep insights into the fundamental composition and origins of the complex world of aquaculture fish aroma.

A comprehensive study on the autochthonous microbiota, volatilome, physico-chemical, and morpho-textural features of Montenegrin Njeguški cheese

The present study aims to deepen the knowledge of the microbiota, gross composition, physico-chemical and morpho-textural features, biogenic amines content and volatilome of Njeguški cheese, one of the most popular indigenous cheeses produced in Montenegro. Cheese samples were collected in duplicate from three different batches produced by three Montenegrin artisan producers. For the first time, the microbiota of Njeguški cheese was investigated using both culture-dependent techniques and metagenomic analysis. Coagulase positive staphylococci viable counts were below the detection limit of the analysis (<1 log cfu g−1). Salmonella spp., Listeria monocytogenes and staphylococcal enterotoxins were absent. However, relatively high viable counts of Enterobacteriaceae, Escherichia coli, Pseudomonadaceae and eumycetes were detected. Metataxonomic analysis revealed a core microbiome composed of Lactococcus lactis, Streptococcus thermophilus, Debaryomyces hansenii, and Kluyveromyces marxianus. Furthermore, the detection of opportunistic pathogenic yeasts such as Magnusiomyces capitatus and Wickerhamiella pararugosa, along with the variable content of biogenic amines, suggests the need for increased attention to hygienic conditions during Njeguški cheese production. Significant variability was observed in humidity (ranging from 38.37 to 45.58 %), salt content (ranging from 0.70 to 1.78 %), proteins content (ranging from 21.42 to 25.08 %), ash content (ranging from 2.97 to 4.05 %), hardness, springiness, and color among samples from different producers. Gas chromatography-mass spectrometry analysis showed a well-defined and complex volatilome profile of the Njeguški cheese, with alcohols (ethanol, isoamyl alcohol, phenetyl alcol), esters and acetates (ethyl acetate, ethyl butanoate, isoamyl acetate), ketones (acetoin, 2-butanone), and acids (acetic, butanoic, hexanoic acids) being the main chemical groups involved in aroma formation. This research will provide new insights into the still poorly explored identity of Njeguški cheese, thus serving as a first baseline for future studies aimed at protecting its tradition.

Metagenomic and Metabolomic Profiling Reveals the Differences of Flavor Quality between Hongqu Rice Wines Fermented with Gutian Qu and Wuyi Qu.

Jiuqu (starter) makes an important contribution to the formation of the flavor characteristics of Hongqu rice wine (HQW). Gutian Qu (GTQ) and Wuyi Qu (WYQ) are two kinds of Jiuqu commonly used in HQW brewing, but the comparison of the two kinds of HQW is still insufficient at present. The objective of this study was to compare the dynamic changes of amino acids (AAs), higher alcohols (HAs), bioamines (BAs), volatile flavor compounds (VFCs), and microbial communities in HQW fermentation, with GTQ and WYQ as starter. This study used an automatic amino acid analyzer, GC, HPLC, and GC-MS to detect AAs, HAs, Bas, and VFCs during fermentation; metagenomic sequencing technology was used to elucidate the microbial community and its functional characteristics. The results showed that the contents of AAs and HAs in HQW brewed with WYQ (WYW) were significantly higher than those in HQW brewed with GTQ (GTW). On the contrary, the majority of BAs in GTW were significantly higher than those in WYW. The composition of VFCs in WYW and GTW were obviously different, as most of the VFCs were notably enriched in WYW, while ethyl caproate, isoamyl acetate, ethyl heptanoate, ethyl nonanoate, 1-decanol, citronellol, phenethyl acetate, and hexanoic acid were more abundant in GTW. Burkholderia gladioli, Pantoea dispersa, Weissella cibaria, Monascus purpureus, and Saccharomyces cerevisiae were the predominant microbial populations in GTW brewing at the species level, while Sphingomonas sp., Kosakonia cowanii, Enterobacter asburiae, Leuconostoc lactis, Aspergillus niger, and Saccharomyces cerevisiae were the dominant microbial species in WYW brewing. The abundance of functional genes involved in BAs biosynthesis were much higher in GTW brewing, while the abundance of functional genes related to the metabolism of characteristic VFCs were much higher in WYW brewing. Collectively, these findings provided evidence for elucidating the effects of Jiuqu and microbial communities on HQW flavor quality, and laid a solid foundation for the improvement of HQW flavor quality.

Impact of the use of an indigenous starter on microbial community structuring and aromatic profile of rocamadour protected designation of origin cheese

The use of indigenous strains as starters offers new opportunities that challenge the use of industrial starters, especially to strengthen the link between Protected Designation of Origin (PDO) cheeses and their terroir. This study investigated the effect of two starters, industrial and indigenous, on the microbial ecosystem and volatile organic compounds (VOCs) in Rocamadour PDO cheese. Metabarcoding analysis showed that regardless of the type of starter used, Lactococcus lactis and Geotrichum candidum largely dominated the microbial communities of Rocamadour (>96 %). The analysis of β-diversity based on the Bray-Curtis indices differentiated the starters according to their bacterial communities. VOC analysis showed that the starters were distinguished by three fatty acids characteristic of the goat cheese aroma (p-value <0.05): decanoic, hexanoic, and octanoic acids. Hexanoic acid was not present in cheeses produced with the indigenous starter. This fatty acid was positively correlated with the presence of Paucilactobacillus nenjiangensis, Lactiplantibacillus sp. and Enterobacteriaceae, these microorganisms that were also characteristic of cheeses made with the industrial starter. Octanoic and decanoic acid, on the other hand, were suggested to be correlated with the presence of Leuconostoc mesenteroides.Cheeses produced with the indigenous starter differed in bacterial communities and aromatic signatures.

Understanding the Flexibility Challenges of a Plant for Microbial CO2 Electroreduction with Hexanoic Acid Recovery

Understanding the Flexibility Challenges of a Plant for Microbial CO₂ Electroreduction with Hexanoic Acid Recovery

The Physicochemical and Nutritional Analysis of Coconut Oil (Cocos nucifera) Extracted from the Tall Tree Variety

Aims: Coconut (Cocos nucifera) known as the ‘tree of life’ is an ancient fruit belonging to the palm family Arecaceae family and the only species in the genus Cocos. This study aims to characterize and show the nutritional qualities of coconut oil from the tall tree variety. Methodology: The production methods include natural Fermentation, centrifugation, freeze-thawing, and solvent extraction. In physical and chemical properties, the moisture content, impurity, specific gravity, refractive index, oil yield, flash, fire, smoke point, melting point, thiobarbituric acid number, saponification, peroxide, iodine, and fatty acid value were analyzed and all fall within close ranges. Results: The fat-soluble vitamins ranged from 18.65 ± 5.09 (vitamin A), 4.28 ± 0.68 (vitamin E), 4.11 ± 3.11(vitamin D) and 1.03 ± 0.21 (vitamin K) all in mg/100ml. Mineral analysis shows that coconut oil contains calcium, zinc, and iron with concentrations of 2.53 ± 0.23, 1.21 ± 0.19, and 0.53 ± 0.13 in mg/100ml respectively. Fatty acid analysis shows that coconut oil contains lauric, myristic, palmitic, caprylic, oleic, capric, stearic, linoleic, and caproic acid of which lauric acid was the highest with a range of 48.40 ± 0.23. Conclusion: The result shows that coconut is a good source of nutrients and the fatty acids make it a good moisturizer.