RÉSUMÉ
Foods contaminants pose a challenge for food producers and consumers. Due to its spontaneous formation during heating and storage, hydroxymethylfurfural (HMF) is a prevalent contaminant in foods rich in carbohydrates and proteins. Colorimetric assays, such as the Seliwanoff test, offer a rapid and cost-effective method for HMF quantification but require careful optimization to ensure accuracy. We addressed potential interference in the Seliwanoff assay by systematically evaluating parameters like incubation time, temperature, and resorcinol or hydrochloric acid concentration, as well as the presence of interfering carbohydrates. Samples were analyzed using a UV-Vis spectrophotometer in scan mode, and data obtained were validated using HPLC, which also enabled quantification of unreacted HMF for assessing the protocol's accuracy. Incubation time and hydrochloric acid percentage positively influenced the colorimetric assay, while the opposite effect was observed with the increase in resorcinol concentration. Interference from carbohydrates was eliminated by reducing the acid content in the working reagent. HPLC analyses corroborated the spectrophotometer data and confirmed the efficacy of the proposed method. The average HMF content in balsamic vinegar samples was 1.97 ± 0.94 mg/mL. Spectrophotometric approaches demonstrated to efficiently determine HMF in complex food matrices. The HMF levels detected in balsamic vinegars significantly exceeded the maximum limits established for honey. This finding underscores the urgent need for regulations that restrict contaminant levels in various food products.
Sujet(s)
Furfural , Spectrophotométrie , Furfural/analogues et dérivés , Furfural/analyse , Spectrophotométrie/méthodes , Chromatographie en phase liquide à haute performance/méthodes , Résorcinol/analyse , Résorcinol/composition chimique , Contamination des aliments/analyse , Analyse d'aliment/méthodes , Acide acétique/analyse , Acide acétique/composition chimiqueRÉSUMÉ
Background: This study explored the utilization of luffa sponge (LS) in enhancing acetification processes. LS is known for having high porosity and specific surface area, and can provide a novel means of supporting the growth of acetic acid bacteria (AAB) to improve biomass yield and acetification rate, and thereby promote more efficient and sustainable vinegar production. Moreover, the promising potential of LS and luffa sponge coated with κ-carrageenan (LSK) means they may represent effective alternatives for the co-production of industrially valuable bioproducts, for example bacterial cellulose (BC) and acetic acid. Methods: LS and LSK were employed as adsorbents for Acetobacter pasteurianus UMCC 2951 in a submerged semi-continuous acetification process. Experiments were conducted under reciprocal shaking at 1 Hz and a temperature of 32 °C. The performance of the two systems (LS-AAB and LSK-AAB respectively) was evaluated based on cell dry weight (CDW), acetification rate, and BC biofilm formation. Results: The use of LS significantly increased the biomass yield during acetification, achieving a CDW of 3.34 mg/L versus the 0.91 mg/L obtained with planktonic cells. Coating LS with κ-carrageenan further enhanced yield, with a CDW of 4.45 mg/L. Acetification rates were also higher in the LSK-AAB system, reaching 3.33 ± 0.05 g/L d as opposed to 2.45 ± 0.05 g/L d for LS-AAB and 1.13 ± 0.05 g/L d for planktonic cells. Additionally, BC biofilm formation during the second operational cycle was more pronounced in the LSK-AAB system (37.0 ± 3.0 mg/L, as opposed to 25.0 ± 2.0 mg/L in LS-AAB). Conclusions: This study demonstrates that LS significantly improves the efficiency of the acetification process, particularly when enhanced with κ-carrageenan. The increased biomass yield, accelerated acetification, and enhanced BC biofilm formation highlight the potential of the LS-AAB system, and especially the LSK-AAB variant, in sustainable and effective vinegar production. These systems offer a promising approach for small-scale, semi-continuous acetification processes that aligns with eco-friendly practices and caters to specialized market needs. Finally, this innovative method facilitates the dual production of acetic acid and bacterial cellulose, with potential applications in biotechnological fields.
Sujet(s)
Acide acétique , Acetobacter , Biomasse , Carragénane , Carragénane/composition chimique , Acetobacter/métabolisme , Acide acétique/composition chimique , Acide acétique/métabolisme , Luffa/composition chimique , Adsorption , Cellulose/métabolisme , Cellulose/composition chimique , Biofilms/croissance et développementRÉSUMÉ
The typically low solubility and gelation capacity of plant proteins can impose challenges in the design of high-quality plant-based foods. The acid used during the precipitation step of plant protein isolate extraction can influence protein functionality. Here, acetic acid and citric acid were used to extract quinoa protein isolate (QPI) from quinoa flour, as these acids are more kosmotropic than the commonly used HCl, promoting the stabilisation of the native protein structure. While proximate analysis showed that total protein was similar for the three isolates, precipitation with kosmotropic acids increased soluble protein, which correlated positively with gel strength. Microstructure analysis revealed that these gels contained a less porous protein network with lipid droplet inclusions. This study shows that the choice of precipitation acid offers an opportunity to tailor the properties of quinoa protein isolate for application, a strategy that is likely applicable to other plant protein isolates.
Sujet(s)
Chenopodium quinoa , Protéines végétales , Chenopodium quinoa/composition chimique , Protéines végétales/composition chimique , Protéines végétales/isolement et purification , Solubilité , Acide citrique/composition chimique , Acide acétique/composition chimique , Précipitation chimique , Farine/analyseRÉSUMÉ
This article employs six organic acids to selectively dissolve Mo, Ni and V from spent catalysts, and the most effective acid is identified. Then, the effects of key leaching parameters, including acid concentration, temperature, and S/L ratio, on metal leaching are systematically explored to determine the leaching mechanism. The results demonstrate that the leaching ability of organic acids followed the order: oxalic acid > citric acid > tartaric acid > malonic acid > acetic acid > formic acid. The leaching process of metals was jointly influenced by acidolysis and complexolysis. Among them, more than 93.07 % of Mo, 86.64 % of V, and 74.21 % of Ni were selectively leached with oxalic acid at the optimum condition: S/l: 1/20, oxalic acid: 1.0 mol/L, temp: 60 °C. From the correlation coefficients, the resulting activation energies, and n values, it was demonstrated that Mo and V followed the Avrami dissolution reaction model, V leaching was controlled by the diffusion mode, and Mo leaching was controlled by a mixed mode of chemical reaction and diffusion. The dissolution behavior of both metals consistently adhered to the linear trend of the Avrami kinetic model under varying S/L ratios and oxalic acid concentrations.
Sujet(s)
Molybdène , Nickel , Acide oxalique , Cinétique , Nickel/composition chimique , Catalyse , Acide oxalique/composition chimique , Molybdène/composition chimique , Tartrates/composition chimique , Acide citrique/composition chimique , Formiates/composition chimique , Acide acétique/composition chimique , MalonatesRÉSUMÉ
Three environmentally friendly organic acids, acetic acid, citric acid and oxalic acid, were used to treat citrus insoluble dietary fiber (CIDF) in present study, aiming to explore the changes in structural properties as well as their inhibitory effects on starch digestion. The results showed that organic acid treatment significantly reduced the particle size of all three CIDFs, with rougher and folded surfaces, improved crystallinity and thermal stability. During in vitro digestion, it was found that organic acid treatment could increase the particle size and viscosity of digestion, and also effectively enhance the inhibitory ability of α-glucosidase activity, resulting in a further blockage of starch digestion. The starch digestion in oxalic acid-treated group (with 3 wt% addition) was significantly reduced by 18.72 % compared to blank group and 9.05 % compared to untreated. These findings provide evidence of the potential of organic acid-treated insoluble dietary fiber as a functional food.
Sujet(s)
Citrus , Fibre alimentaire , Solubilité , Amidon , Citrus/composition chimique , Amidon/composition chimique , Amidon/métabolisme , Digestion/effets des médicaments et des substances chimiques , Taille de particule , Acide citrique/composition chimique , Viscosité , alpha-Glucosidase/métabolisme , alpha-Glucosidase/composition chimique , Acide acétique/composition chimique , Acide oxalique/composition chimiqueRÉSUMÉ
The increased interest in the utilization of lignin in biobased applications is evident from the rise in lignin valorization studies. The present study explores the responsiveness of lignin toward oxidative valorization using acetic acid and hydrogen peroxide. The pristine lignins and their oxidized equivalents were analyzed comprehensively using NMR and SEC. The study revealed ring opening of phenolic rings yielding muconic acid- and ester-end groups and side-chain oxidations of the benzylic hydroxyls. Syringyl units were more responsive to these reactions than guaiacyl units. The high selectivity of the reaction yielded oligomeric oxidation products with a narrower dispersity than pristine lignins. Mild alkaline hydrolysis of methyl esters enhanced the carboxylic acid content of oxidized lignin, presenting the potential to adjust the carboxylic acid content of lignin. While oxidation reactions in lignin valorization are well documented, this study showed the feasibility of employing optimized oxidation conditions to engineer tailored lignin-based material precursors.
Sujet(s)
Lignine , Oxydoréduction , Lignine/composition chimique , Peroxyde d'hydrogène/composition chimique , Acides carboxyliques/composition chimique , Acide acétique/composition chimique , HydrolyseRÉSUMÉ
In the present study, pyroligneous acid, also known as wood vinegar, has been employed as reducing and stabilizing agent in the synthesis of silver nanoparticles (AgNPs) anchored on nanocellulose (NC). The idea is to confer the latter bactericidal properties for its typical uses such as in cosmetics and food-packing. It has been demonstrated that AgNPs can be directly produced onto NC in one-pot fashion while dramatically enhancing the kinetics of AgNPs synthesis (2 h for reaction completion) in comparison to the NC-less counterpart (10 days for reaction completion). Furthermore, NC allowed for a narrower size distribution of AgNPs. NC-supported and non-supported AgNPs had sizes of 5.1 ± 1.6 nm and 16.7 ± 4.62 nm, respectively. Immortalized human keratinocytes (HaCat) cells were then employed as model to evaluate the cytotoxicity of the AgNPs-NC compound. The latter was found not to impact cell proliferation at any formulation, while decreasing the viability by only 6.8% after 72 h. This study contributes to the development of more environmentally benign routes to produce nanomaterials and to the understanding of their impact on cells.
Sujet(s)
Survie cellulaire , Cellulose , Cellules HaCaT , Nanoparticules métalliques , Argent , Humains , Argent/composition chimique , Nanoparticules métalliques/composition chimique , Cellulose/composition chimique , Cellulose/pharmacologie , Survie cellulaire/effets des médicaments et des substances chimiques , Kératinocytes/effets des médicaments et des substances chimiques , Kératinocytes/cytologie , Taille de particule , Prolifération cellulaire/effets des médicaments et des substances chimiques , Acide acétique/composition chimique , Acide acétique/pharmacologieRÉSUMÉ
Acetic acid bacteria (AAB) and other members of the complex microbiotas, whose activity is essential for vinegar production, display biodiversity and richness that is difficult to study in depth due to their highly selective culture conditions. In recent years, liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) has emerged as a powerful tool for rapidly identifying thousands of proteins present in microbial communities, offering broader precision and coverage. In this work, a novel method based on LC-MS/MS was established and developed from previous studies. This methodology was tested in three studies, enabling the characterization of three submerged acetification profiles using innovative raw materials (synthetic alcohol medium, fine wine, and craft beer) while working in a semicontinuous mode. The biodiversity of existing microorganisms was clarified, and both the predominant taxa (Komagataeibacter, Acetobacter, Gluconacetobacter, and Gluconobacter) and others never detected in these media (Asaia and Bombella, among others) were identified. The key functions and adaptive metabolic strategies were determined using comparative studies, mainly those related to cellular material biosynthesis, energy-associated pathways, and cellular detoxification processes. This study provides the groundwork for a highly reliable and reproducible method for the characterization of microbial profiles in the vinegar industry.
Sujet(s)
Acide acétique , Protéines bactériennes , Spectrométrie de masse en tandem , Spectrométrie de masse en tandem/méthodes , Acide acétique/métabolisme , Acide acétique/analyse , Acide acétique/composition chimique , Chromatographie en phase liquide/méthodes , Protéines bactériennes/métabolisme , Protéines bactériennes/analyse , Bactéries/métabolismeRÉSUMÉ
Methyl parathion, a highly toxic, efficient, and persistent organophosphorus pesticide, is widely used in China. Sibutramine, a non-amphetamine central nervous system depressant, helps lose weight by disrupting hormone regulation, stimulating sympathetic nerves, and suppressing appetite. However, some unethical businesses fail to properly handle raw materials in foods like apple cider vinegar, leading to residual methyl parathion in apples or illegal excessive addition of sibutramine. Therefore, it is imperative to develop an immunoassay for the rapid detection of methyl parathion and sibutramine. The corresponding two haptens were prepared and coupled with the carrier proteins according to methyl parathion-sulfur-bovine serum protein (BSA)/chicken ovalbumin (OVA)-sibutramine (20 : 1 : excess, 15 : 1 : excess, 10 : 1 : excess, and 5 : 1 : excess), and sibutramine-BSA/OVA-methyl parathion (20 : 1 : excess, 10 : 1 : excess: 5 : 1 : excess, and 0 : 1 : excess). The result shows that the inhibition rate of the antibody obtained by methyl parathion-BSA/OVA-sibutramine (20 : 1 : excess) was higher than that of sibutramine-BSA/OVA-methyl parathion, which was 67.93%, and the concentration of methyl parathion was 8.65 ng mL-1 at this inhibition rate. Thus, methyl parathion-BSA/OVA-sibutramine (8.65 : 1 : excess) and the corresponding antibodies were selected for subsequent method establishment. By changing the concentration of the coating and antibody, the inhibition rate was found when the coating was 0.125 ng mL-1 and the antibody was diluted 4000 times. The antibody was used to develop a standard curve for the detection of sibutramine at the half-maximum inhibitory concentration (IC50) is 4.59 ng mL-1, the limit of detection (IC10) is 2.21 ng mL-1, the detection range is 2.89 to 7.28 ng mL-1, methyl p-phosphorus at the half-maximum inhibitory concentration (IC50) is 15.34 ng mL-1, the limit of detection (IC10) is 0.42 ng mL-1, the detection range is ng mL-1. Under these conditions, the recovery rate was between 88% and 102%, within reasonable limits, indicating the successful establishment of a rapid enzyme-linked ELISA assay.
Sujet(s)
Cyclobutanes , Test ELISA , Malus , Parathion-méthyl , Cyclobutanes/composition chimique , Test ELISA/méthodes , Malus/composition chimique , Parathion-méthyl/analyse , Acide acétique/composition chimique , Anorexigènes/analyse , Anorexigènes/composition chimique , Contamination des aliments/analyse , Animaux , Limite de détectionRÉSUMÉ
The quality of the grains during the fumigation process can significantly affect the flavour and nutritional value of Shanxi aged vinegar (SAV). Hyperspectral imaging (HSI) was used to monitor the extent of fumigated grains, and it was combined with chemometrics to quantitatively predict three key physicochemical constituents: moisture content (MC), total acid (TA) and amino acid nitrogen (AAN). The noise reduction effects of five spectral preprocessing methods were compared, followed by the screening of optimal wavelengths using competitive adaptive reweighted sampling. Support vector machine classification was employed to establish a model for discriminating fumigated grains, and the best recognition accuracy reached 100%. Furthermore, the results of partial least squares regression slightly outperformed support vector machine regression, with correlation coefficient for prediction (Rp) of 0.9697, 0.9716, and 0.9098 for MC, TA, and AAN, respectively. The study demonstrates that HSI can be employed for rapid non-destructive monitoring and quality assessment of the fumigation process in SAV.
Sujet(s)
Acide acétique , Algorithmes , Fumigation , Imagerie hyperspectrale , Spectroscopie proche infrarouge , Fumigation/méthodes , Spectroscopie proche infrarouge/méthodes , Acide acétique/composition chimique , Imagerie hyperspectrale/méthodes , Chimiométrie/méthodes , Machine à vecteur de support , Méthode des moindres carrésRÉSUMÉ
Low-Field Nuclear Magnetic Resonance (LF-NMR) can be a valid tool in food fingerprint analyses to detect commercial frauds. Thus, the work aims at exploring the potential of LF-NMR, coupled with chemometrics, in discriminating authentic white wine vinegars from products adulterated with alcohol vinegars (i.e., 5-25% v/v adulteration levels). The monodimensional spectra and transverse relaxation times (T2) of 88 samples, including 32 authentic vinegars and 56 adulterated samples, were collected. Three different spectral regions were investigated (i.e., 3.75-0.90, 3.75-2.00, and 1.50-0.90 ppm) and, for each, fifteen variables were selected from the pretreated monodimensional spectra. Linear Discriminant Analysis (LDA) on monodimensional spectra in the range 3.75-0.90 ppm gave 100% correct classification of authentic and adulterated vinegars in prediction, whereas LDA models developed with acetic acid or water T2 failed. In conclusion, LF-NMR spectra can be effectively used to detect, in a rapid and non-destructive way, white wine vinegar adulteration with alcohol vinegar.
Sujet(s)
Acide acétique , Contamination des aliments , Spectroscopie par résonance magnétique , Vin , Acide acétique/analyse , Acide acétique/composition chimique , Vin/analyse , Contamination des aliments/analyse , Analyse discriminanteRÉSUMÉ
Depolymerization of the cellulose part in lignocellulose to glucose is a significant step for lignocellulose valorization. As one of the main by-products of agricultural biomass in crop-producing filed, valorization of corn straw has attracted considerable attention. In this study, a two-step depolymerizing strategy of high-pressure CO2-H2O pretreatment and oxidation-hydrolysis was applied for selective depolymerization of the cellulose component of corn straw to glucose production. Most part of the hemicellulose component could be removed through high-pressure CO2-H2O pretreatment in the presence of low concentration of acetic acid, and then as high as 32.2 % yield of glucose was achieved in water at 170 °C for 6â h without additional catalyst. The active acid sites generated during the partial oxidation of hydroxymethyl groups to carboxyl groups on glucose units of cellulose was shown to be crucial for the efficient valorization of corn straw for glucose production.
Sujet(s)
Biomasse , Cellulose , Glucose , Lignine , Polymérisation , Zea mays , Zea mays/composition chimique , Glucose/composition chimique , Glucose/métabolisme , Cellulose/composition chimique , Lignine/composition chimique , Hydrolyse , Oxydoréduction , Dioxyde de carbone/composition chimique , Eau/composition chimique , Acide acétique/composition chimique , Catalyse , Polyosides/composition chimiqueRÉSUMÉ
This research presents a new, eco-friendly, and swift method combining solid-phase extraction and hydrophobic deep eutectic solvents (DES) with high-performance liquid chromatography (SPE-DES-HPLC) for extracting and quantifying catechin and epicatechin in Shanxi aged vinegar (SAV). The parameters, such as the elution solvent type, the XAD-2 macroporous resin dosage, the DES ratio, the DES volume, the adsorption time, and the desorption time, were optimized via a one-way experiment. A central composite design using the Box-Behnken methodology was employed to investigate the effects of various factors, including 17 experimental runs and the construction of three-dimensional response surface plots to identify the optimal conditions. The results show that the optimal conditions were an HDES (tetraethylammonium chloride and octanoic acid) ratio of 1:3, an XAD-2 macroporous resin dosage of 188 mg, and an adsorption time of 11 min. Under these optimal conditions, the coefficients of determination of the method were greater than or equal to 0.9917, the precision was less than 5%, and the recoveries ranged from 98.8% to 118.8%. The environmentally friendly nature of the analytical process and sample preparation was assessed via the Analytical Eco-Scale and AGREE, demonstrating that this method is a practical and eco-friendly alternative to conventional determination techniques. In summary, this innovative approach offers a solid foundation for the assessment of flavanol compounds present in SAV samples.
Sujet(s)
Acide acétique , Catéchine , Solvants eutectiques profonds , Interactions hydrophobes et hydrophiles , Extraction en phase solide , Chromatographie en phase liquide à haute performance/méthodes , Extraction en phase solide/méthodes , Acide acétique/composition chimique , Catéchine/composition chimique , Catéchine/analyse , Solvants eutectiques profonds/composition chimique , AdsorptionRÉSUMÉ
We describe a microwave-assisted, methanol and acetic acid-free, inexpensive method for rapid staining of SDS-PAGE proteins. Only citric acid, benzoic acid, and Coomassie brilliant blue G-250 (CBG) were used. Microwave irradiation reduced the detection duration, and proteins in a clear background were visualized within 30 min of destaining, after 2 min of fixing and 12 min of staining. By using this protocol, comparable band intensities were obtained to the conventional methanol/acetic acid method.
Sujet(s)
Acide acétique , Électrophorèse sur gel de polyacrylamide , Méthanol , Micro-ondes , Protéines , Électrophorèse sur gel de polyacrylamide/méthodes , Méthanol/composition chimique , Protéines/analyse , Acide acétique/composition chimique , Coloration et marquage/méthodes , Magenta I/composition chimiqueRÉSUMÉ
Shanxi aged vinegar microbiome encodes a wide variety of bacteriocins. The aim of this study was to mine, screen and characterize novel broad-spectrum bacteriocins from the large-scale microbiome data of Shanxi aged vinegar through machine learning, molecular simulation and activity validation. A total of 158 potential bacteriocins were innovatively mined from 117,552 representative genes based on metatranscriptomic information from the Shanxi aged vinegar microbiome using machine learning techniques and 12 microorganisms were identified to secrete bacteriocins at the genus level. Subsequently, employing AlphaFold2 structure prediction and molecular dynamics simulations, eight bacteriocins with high stability were further screened, and all of them were confirmed to have bacteriostatic activity by the Escherichia coli BL21 expression system. Then, gene_386319 (named LAB-3) and gene_403047 (named LAB-4) with the strongest antibacterial activities were purified by two-step methods and analyzed by mass spectrometry. The two bacteriocins have broad-spectrum antimicrobial activity with minimum inhibitory concentration values of 6.79⯵g/mL-15.31⯵g/mL against Staphylococcus aureus and Escherichia coli. Furthermore, molecular docking analysis indicated that LAB-3 and LAB-4 could interact with dihydrofolate reductase through hydrogen bonds, salt-bridge forces and hydrophobic forces. These findings suggested that the two bacteriocins could be considered as promising broad-spectrum antimicrobial agents.
Sujet(s)
Acide acétique , Antibactériens , Bactériocines , Apprentissage machine , Simulation de docking moléculaire , Acide acétique/composition chimique , Acide acétique/métabolisme , Acide acétique/pharmacologie , Bactériocines/composition chimique , Bactériocines/pharmacologie , Bactériocines/génétique , Antibactériens/pharmacologie , Antibactériens/composition chimique , Microbiote , Escherichia coli/effets des médicaments et des substances chimiques , Escherichia coli/génétique , Simulation de dynamique moléculaire , Staphylococcus aureus/effets des médicaments et des substances chimiques , Tests de sensibilité microbienneRÉSUMÉ
Vinegar is renowned for its benefits to human health due to the presence of antioxidants and bioactive components. Firstly, this study optimized the production conditions of ultrasound-treated strawberry vinegar (UT-SV), known for its high consumer appeal. The sensory properties of UT-SV were optimized by response surface methodology (RSM) to create the most appreciated strawberry vinegar. Secondly, various quality parameters of conventional strawberry vinegar (C-SV), UT-SV, and thermally pasteurized strawberry vinegar (P-SV) samples were compared. RSM was employed to craft the best strawberry vinegar based on consumers ratings of UT-SV. Sensory characteristics, bioactive values, phenolic contents, and organic acid contents of C-SV, UT-SV, and P-SV samples were assessed. Through optimization, the ultrasound parameters of the independent variables were determined as 5.3 min and 65.5 % amplitude. The RSM modeling levels exhibited high agreement with pungent sensation at 98.06 %, aromatic intensity at 98.98 %, gustatory impression at 99.17 %, and general appreciation at 99.26 %, respectively. Bioactive components in UT-SV samples increased after ultrasound treatment compared to C-SV and P-SV samples. Additionally, the amount of malic acid, lactic acid, and oxalic acid increased after ultrasound treatment compared to C-SV samples. Ultimately, UT-SV with high organoleptic properties was achieved. The ultrasound treatment positively impacted the bioactive values, phenolic and organic acid content, leading to the development of a new and healthy product.
Sujet(s)
Acide acétique , Fragaria , Fragaria/composition chimique , Acide acétique/composition chimique , Acide acétique/analyse , Ondes ultrasonores , Goût , Phénols/analyseRÉSUMÉ
Acetic acid is the key organic substance used to verify the authenticity of vinegar. A new method for precisely determining acetic acid δDCH3 in vinegar via gas chromatography -pyrolytic-stable isotope ratio mass spectrometry (GC-P-IRMS) was established. The δDCH3 values were obtained via calibration with a series of standards. The optimised method demonstrated a repeatability standard deviation within 3 . The standard deviation of accuracy of the new method compared with that of the SNIF-NMR method was within 2.6 . The synthetic acetic acid δDCH3 values was -136.7 ± 29.6 , and the δDCH3 value of acetic acid in vinegar was -414.9 ± 40.5 , with significant isotopic distribution characteristics. This methodology serves as a supplementary method for measuring the δDCH3 value of acetic acid in vinegar. It has advantages over other methods in terms of time, sensitivity and operability. And provides a new idea for solving the problem of analyzing substances in the presence of exchangeable groups.
Sujet(s)
Acide acétique , Chromatographie gazeuse-spectrométrie de masse , Acide acétique/composition chimiqueRÉSUMÉ
The effects of different types of acid coagulants and nano fish bone (NFB) additives on the characteristics of tofu were investigated using texture analyzers, SEM, FT-IR, and other techniques. The breaking force and penetration distance, in descending order, were found in the tofu induced by glucono-d-lactone (GDL) (180.27 g and 0.75 cm), citric acid (152.90 g and 0.74 cm), lactic acid (123.33 g and 0.73 cm), and acetic acid (69.84 g and 0.58 cm), respectively. The syneresis of these tofu samples was in the reverse order (35.00, 35.66, 39.66, and 44.50%). Lightness and whiteness were not significantly different among the different samples. Regardless of the acid type, the soluble calcium content in the soybean milk was significantly increased after adding NFB. As a result, the breaking force and penetration distance of all tofu samples increased significantly, but the syneresis decreased. Compared with tofu coagulated by other acids, GDL tofu formed a more uniform and dense gel network maintained by the highest intermolecular forces (especially hydrophobic interactions). Regarding the secondary structure, the lowest percentage of α-helix (22.72%) and, correspondingly, the highest ß-sheet (48.32%) and random coil (18.81%) were noticed in the GDL tofu. The effects of NFB on the tofu characteristics can be explained by the changes in the gel network, intermolecular forces, and secondary structure, which were in line with the acid type. The characteristics of acid-induced tofu can be most synergistically improved by coagulation with GDL and NFB.
Sujet(s)
Gels , Gels/composition chimique , Animaux , Glycine max/composition chimique , Spectroscopie infrarouge à transformée de Fourier/méthodes , Acide acétique/composition chimique , Poissons , Acide citrique/composition chimique , Gluconates/composition chimique , Acide lactique/composition chimique , Interactions hydrophobes et hydrophiles , Manipulation des aliments/méthodes , Microscopie électronique à balayage/méthodes , LactonesRÉSUMÉ
Low bioavailability of quercetin (Que) reduces its preclinical and clinical benefits. In order to improve Que bioavailability, a novel whey protein isolate (WPI)-zein nanogel was prepared by pH-driven self-assembly and heat-induced gelatinization. The results showed that hydrochloric acid can be substituted by both acetic acid and citric acid during the pH-driven process. After encapsulation, the bioavailability of Que in nanogels (composed of 70 % WPI) induced by different acidifiers increased to 19.89 % (citric acid), 21.65 % (hydrochloric acid) and 24.34 % (acetic acid), respectively. Comparatively, nanogels induced by acetic acid showed higher stability (pH and storage stability), re-dispersibility (75.62 %), Que bioavailability (24.34 %), and antioxidant capacity (36.78 % for DPPH scavenging rates). s improved performance of nanogels. In mechanism, acetic acid significantly balanced different intermolecular forces by weakening "acid-induced denaturation" effect. Moreover, the faster binding of Que and protein as well as higher protein molecular flexibility and randomness (higher ratio of random coil) was also observed in nanogels induced by acetic acid. All of these changes contributed to improve nanogels performances. Overall, WPI-zein nanogels induced by acetic acid might be a safe, efficiency and stable delivery system to improve the bioavailability of hydrophobic active ingredients.
Sujet(s)
Antioxydants , Biodisponibilité , Nanogels , Quercétine , Protéines de lactosérum , Zéine , Quercétine/composition chimique , Quercétine/pharmacologie , Protéines de lactosérum/composition chimique , Zéine/composition chimique , Antioxydants/composition chimique , Antioxydants/pharmacologie , Nanogels/composition chimique , Concentration en ions d'hydrogène , Acide acétique/composition chimique , Polyéthylèneimine/composition chimique , Polyéthylène glycols/composition chimique , Stabilité de médicament , Vecteurs de médicaments/composition chimiqueRÉSUMÉ
Rhodanine-3-acetic acid derivatives are attractive compounds with versatile effects. What is very important is that compounds of this type have many biological properties. They are tested, among others, as fluorescent probes for bioimaging and aldose reductase inhibitors. Rhodanine-3-acetic acid derivatives also have antibacterial, antifungal and anticancer activity. The presented work demonstrates that a slight change in the five-membered heterocyclic substituent significantly affects the properties of the compounds under consideration. Three rhodanine-3-acetic acid derivatives (A-1-A-3) were obtained in the Knoevenagel condensation reaction with good yields, ranging from 54% to 71%. High thermal stability of the tested compounds was also demonstrated above 240 °C. The absorption and emission maxima in polar and non-polar solvents were determined. Then, the possibility of using the considered derivatives for fluorescence bioimaging was checked. Compounds A-1 and A-2 were successfully used as fluorescent dyes of fixed cells of mammalian origin. In addition, biological activity tests against bacteria and fungi were carried out. Our results showed that A-1 and A-2 showed the most excellent antimicrobial activity among the newly synthesized compounds, especially against Gram-positive bacteria.