Organic Acid Content Research Articles

Testing a Simulation Model for the Response of Tomato Fruit Quality Formation to Temperature and Light in Solar Greenhouses.

Temperature and light are the key factors affecting the formation of tomato fruit quality in greenhouse cultivation. However, there are few simulation models that examine the relationship between tomato fruit quality formation and temperature and light. In this study, a model was established that investigated the relationships between soluble sugar (SSC), organic acid content (OAC), and SSC/OAC and the cumulative product of thermal effectiveness and photosynthetically active radiation (TEP) during the fruit-ripening period in a solar greenhouse. The root mean square error (RMSE) values were calculated to compare the consistency between the simulated and measured values, and the RMSE values for SSC, OAC, and SSC/OAC were 0.09%, 0.14%, and 0.358, respectively. The combined weights of quality indicators were obtained using the analytic hierarchy process (AHP) and entropy weighting method, ranking as SSC > OAC > SSC/OAC > CI > lycopene > Vc > fruit firmness. The comprehensive fruit quality evaluation value was obtained using the TOPSIS method (Technique for Order Preference by Similarity to an Ideal Solution) and a simulation model between comprehensive tomato fruit quality and TEP was explored. This study could accurately simulate and quantify the accumulation of tomato fruit quality during fruit ripening in response to environmental conditions in a solar greenhouse.

Integrated analysis of transcriptomics and metabolomics of garden asparagus (Asparagus officinalis L.) under drought stress

BackgroundDrought is a leading environmental factor affecting plant growth. To explore the drought tolerance mechanism of asparagus, this study analyzed the responses of two asparagus varieties, namely, ‘Jilv3’ (drought tolerant) and ‘Pacific Early’ (drought sensitive), to drought stress using metabolomics and transcriptomics.ResultsIn total, 2,567 and 7,187 differentially expressed genes (DEGs) were identified in ‘Pacific Early’ and ‘Jilv3’, respectively, by comparing the transcriptome expression patterns between the normal watering treatment and the drought stress treatment. These DEGs were significantly enriched in the amino acid biosynthesis, carbon metabolism, phenylpropanoid biosynthesis, and plant hormone signal transduction pathways. In ‘Jilv3’, DEGs were also enriched in the following energy metabolism-related pathways: citrate cycle (TCA cycle), glycolysis/gluconeogenesis, and pyruvate metabolism. This study also identified 112 and 254 differentially accumulated metabolites (DAMs) in ‘Pacific Early’ and ‘Jilv3’ under drought stress compared with normal watering, respectively. The amino acid, flavonoid, organic acid, and soluble sugar contents were more significantly enhanced in ‘Jilv3’ than in ‘Pacific Early’. According to the metabolome and transcriptome analysis, in ‘Jilv3’, the energy supply of the TCA cycle was improved, and flavonoid biosynthesis increased. As a result, its adaptability to drought stress improved.ConclusionsThese findings help to better reveal the molecular mechanism underlying how asparagus responds to drought stress and improve researchers’ ability to screen drought-tolerant asparagus varieties as well as breed new varieties.

Revealing the effects of amino acid, organic acid, and phytohormones on the germination of tomato seeds under salinity stress.

Salinity accumulation poses a threat to the production and productivity of economically important crops such as tomatoes (Solanum lycopersicum L.). Currently, salt tolerance breeding programs have been limited by insufficient genetic and physiological knowledge of tolerance-related traits and a lack of an efficient selection domain. For that purpose, we aimed to determine the ability of tomato cultivars to tolerate salt based on seed traits by multiple biochemical pathways. First, we tested three tomato cultivars according to their response to different sodium chloride (NaCl) concentrations (0, 6.3, 9.8, 13.0, and 15.8 dS m-1) and then we analysed their amino acids, organic acids, and phytohormones. Considering the results of germination traits, it is possible to conclude that cultivar H-2274 was more tolerant to salt stress than others. As a result, multivariate discriminant analysis including principal component analysis and two-way hierarchical clustering analyses were constructed and demonstrated that tomato cultivars were separated from each other by the amino acid, organic acid, and phytohormone contents. Considering germination traits of tomato seeds, cv. 'H-2274' was more tolerant to salinity than others depending on high proline (29 pmol µl-1) and citric acid (568 ng µl-1) assays. Biochemical variability offers a valuable tool for investigating salt tolerance mechanisms in tomatoes, and it will be appreciated to find high-tolerant tomato cultivar(s) to saline conditions. Also, the findings of this study have significant potential for practical applications in agriculture, particularly in developing salt-tolerant tomato cultivars to enhance productivity in saline environments and address socio-economic challenges.

Fermentation Performance Evaluation of Lactic Acid Bacteria Strains for Sichuan Radish Paocai Production.

Fermented vegetable products play a significant role in various cuisines, and understanding the fermentation dynamics of lactic acid bacteria (LAB) strains is essential for optimizing their production and quality. Here, we sought to investigate the fermentation performance of five LAB strains isolated from Sichuan paocai as starters for paocai. Sensory evaluation revealed that the inoculation of radish paocai samples with LAB strains effectively improved the overall liking and sensory satisfaction of participants, increasing the scores to varying degrees in terms of taste, flavor, texture, and coloration. Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus exhibited a good salt resistance in radish juice and could grow in a medium containing 10% NaCl. Four indicator strains commonly found in contaminated paocai were effectively inhibited by fermented LAB broths, which improved the edibility and safe production of paocai. Compared to spontaneous fermentation (CK), radish paocai inoculated with LAB showed a significantly accelerated acid production rate, shortening the fermentation period by approximately two days. The contents of titratable total acids, organic acids, and free amino acids were higher in the inoculated samples and were enriched in the taste of radish paocai. The content of volatile organic compounds in the inoculated samples was higher than that in CK. Based on OPLS-DA analysis, 31 key indicators of paocai quality were screened and used to rank the fermentation performances of the five strains using the TOPSIS method; here, Lpb. plantarum and Lcb. rhamnosus achieved the highest scores. This study provides a reference for selecting LAB strains as efficient and secure fermentation starters to optimize paocai quality.

Overexpression of phosphoenolpyruvate carboxylase kinase gene MsPPCK1 from Medicago sativa L. increased alkali tolerance of alfalfa by enhancing photosynthetic efficiency and promoting nodule development

The phosphoenolpyruvate carboxylase kinase of Medicago sativa L. (MsPPCK1) modulates the phosphorylation status and activity of the C4 pathway phosphoenolpyruvate carboxylase enzyme, which is pivotal for photosynthetic carbon assimilation in plants. This study investigated the role of MsPPCK1 in alfalfa by creating transgenic plants overexpressing MsPPCK1 under the control of the CaMV35S promoter. The enhanced alkali tolerance of transgenic plants indicated an important role of MsPPCK1 gene in regulating plant alkali tolerance. Transgenic plants exhibited heightened antioxidant activity (SOD, POD, and CAT), reduced MDA, H2O2, OFR and REC% content, increased activity of key photosynthetic enzymes (PEPC, PPDK, NADP-ME, and NADP-MDH), and enhanced photosynthetic parameters (Pn, E, Gs, and Ci). Moreover, MsPPCK1 overexpression increased the content of organic acids (oxaloacetic, malic, citric, and succinic acids) in the plants. The upregulation of MsPPCK1 under rhizobial inoculation showcased its other role in nodule development. In transgenic plants, MsDMI2, MsEnod12, and MsNODL4 expression increased, facilitating root nodule development and augmenting plant nodulation. Accelerated root nodule growth positively influences plant growth and yield and enhances alfalfa resistance to alkali stress. This study highlights the pivotal role of MsPPCK1 in fortifying plant alkali stress tolerance and improving yield, underscoring its potential as a key genetic target for developing alkali-tolerant and high-yielding alfalfa varieties.

Assessment of quality differences between wild and cultivated fruits of Rosa roxburghii Tratt

Cultivated and wild Rosa roxburghii Tratt were investigated to determine the intrinsic causes of the quality differences. The cultivated fruit, Guinong No. 5 (GNNF) was larger, heavier, and had less color difference. Its juice contained higher levels of soluble solids and tannins. The wild variety (WRRT) had higher concentrations of condensed tannins, polyphenols and flavonoids. Artificial sensory and electronic taste tests indicated GNNF had a lower astringent and bitter taste compared to WRRT. A total of 80 flavour substances were identified by gas chromatography‒mass spectrometry (GC-MS). The relative contents of esters, organic acids, ketones, alcohols, aldehydes and aromatic hydrocarbons were higher in GNNF than in WRRT. Caffeylalcohol, catechin, quinidine, pantothenic acid and five bitter amino acids were high in GNNF. The high contents of bitter substances such as limonin, daidzein, and rutaevin were responsible for the quality differences between WRRT and GNNF.

Coinoculation of Saccharomyces cerevisiae and Bacillus amyloliquefaciens in solid-state and submerged coffee fermentation: Influences on chemical and sensory compositions

This study aimed to evaluate the influence coffee fermentation with yeast and bacillus as starter cultures in SIAF method applied in solid-state and submerged process. Saccharomyces cerevisiae and Bacillus amyloliquefaciens were separately and coinoculated into natural coffee in buckets with or without water adding. The fermentations were performed for until 96 h, and the effects on physicochemical composition including the concentrations of organic acids (citric, lactic, acetic, malic), sugars (glucose, fructose, sucrose), ethanol, and glycerol as well as the sensory profiles of the resulting coffee beverages, were evaluated. All coffees produced were classified in specialty coffee with final score above 84. The coinoculated coffees obtained the highest sensory scores in submerged process (>86). Due to the results found, the type of process, submerged and solid-state, showed more influence in chemical and sensory analyses than type of inoculation. Submerged process showed major concentration of lactic acid, while solid-state process promotes major concentrations of ethanol, glycerol and acetic acid. Different sensory descriptions were observed in each treatment. Coffees from the submerged process showed nutty, cocoa, and sweet sensory descriptions, while solid-state process produced coffees with sour and acidic attributes.

Haplotype-resolved T2T genome assemblies and pangenome graph of pear reveal diverse patterns of allele-specific expression and the genomic basis of fruit quality traits

Hybrid crops often exhibit increased yield and greater resilience, yet the genomic mechanism(s) underlying hybrid vigor or heterosis remain unclear, hindering our ability to predict the expression of phenotypic traits in hybrid breeding. Here, we generated haplotype-resolved T2T genome assemblies of two pear hybrid varieties, ‘Yuluxiang’ (YLX) and ‘Hongxiangsu’ (HXS), which share the same maternal parent but differ in their paternal parents. We then used these assemblies to explore the genome-scale landscape of allele-specific expression (ASE) and create a pangenome graph for pear. ASE was observed for close to 6000 genes in both hybrid cultivars. A subset of ASE genes related to aspects of fruit quality such as sugars, organic acids, and cuticular wax were identified, suggesting their important contributions to heterosis. Specifically, Ma1, a gene regulating fruit acidity, is absent in the paternal haplotypes of HXS and YLX. A pangenome graph was built based on our assemblies and seven published pear genomes. Resequencing data for 139 cultivated pear genotypes (including 97 genotypes sequenced here) were subsequently aligned to the pangenome graph, revealing numerous structural variant hotspots and selective sweeps during pear diversification. As predicted, the Ma1 allele was found to be absent in varieties with low organic acid content, and this association was functionally validated by Ma1 overexpression in pear fruit and calli. Overall, these results reveal the contributions of ASE to fruit-quality heterosis and provide a robust pangenome reference for high-resolution allele discovery and association mapping.

Kombucha beverages made from Camellia nitidissima Chi and Camellia sinensis flowers—physicochemical properties, sensory properties and bioactivity

Recently, various plant materials other than tea have been used as substrates for kombucha beverages. To improve the aroma and other qualities of kombucha, Camellia sinensis and Camellia nitidissima Chi flowers were used as raw materials to prepare novel kombucha beverages (marked as TFK and GFTK), which were systematically compared to traditional kombucha made from black tea. The results revealed that the biomass of kombucha made from TFK increased the most among all samples. TFK had the highest content of organic acids, with 9.03 g/L of acetic acid and 5.57 g/L of gluconic acid. Metabolomic analysis revealed that TFK showed the highest concentration of organic nitrogen compounds, whereas GFTK had the highest concentration of flavonoids. There were 183 kinds of volatile components identified in the 3 kombuchas, only 20 of which were common aroma components. Among the three kombucha beverages, TFK had the highest digestive enzyme inhibitory activity and was also second only to GFTK in terms of anti-oxidant properties. In terms of sensory properties, TFK had a higher fruit score compared to GFTK, but there was no significant difference in floral intensity between these two samples. Therefore, the C. sinensis flower is more suitable for preparing kombucha.

The influence of storage conditions on the quality of Schisandra chinensis fruits: A integrated investigation of constituent and antioxidant activity

Schisandra chinensis is a functional fruit with tonic effect and was widely used by traditional Chinese medicine for treatment and health care. The quality of Schisandra chinensis fruit may vary by different storage condition. In this study, the influence of ambient temperature, humidity, packaging materials and period of storage on the quality of Schisandra chinensis fruits were investigated. The contents of main active components lignans and organic acids were simultaneously determined by ultra-performance liquid chromatography coupled to quadrupole electrostatic field orbitrap high resolution mass spectrometry (UPLC Orbitrap HRMS). The antioxidant activity was determined using DPPH radical scavenging capacity, ABTS+ inhibition rate and FRAP value. The correlation of multicomponent and antioxidant activity was analyzed by grey relevance analysis. Taking the changes of multicomponent and antioxidant activity as investigation index, Schisandra chinensis fruits under different storage conditions was comprehensively evaluated. Schisandrol A, malic acid, sorbic acid, schizandrin A, schizandrin B, and schisandrol B were the main effective components of antioxidant activity. Ambient temperature at 5 °C and humidity at 40 % were more suitable for Schisandra chinensis fruits and kraft paper bag was better packaging material. Do not exceed 1 year was the effective storage period. For the safety evaluation, no aflatoxin was detected within the storage period of 2 years, demonstrated the storage was satisfactory. This study provided a reference for the high-quality storage and standardized operating procedures for storage of Schisandra chinensis fruits.

Mechanism of improving the quality of table grapes (Vitis. spp.) by exogenous eugenol based on transcriptome

SummaryGrape is widely consumed all over the world for its rich nutritious and health‐promoting effects. While grape berries are prone to quality deterioration after harvest. This study aimed to investigate the effect of eugenol treatment on the quality of grape berries based on the transcriptome. Harvested grape berries were treated with eugenol, and then collected for nutrient component determination and transcriptomics analyses. As a results, treatment with eugenol enhanced the berries firmness, increased the contents of soluble sugars, organic acids and phenolic compounds, improved the antioxidant capacity, and altered gene expression levels of related pathways. Transcriptome analysis revealed 699 differentially expressed genes by 100 mmol L−1 eugenol‐treated berries. Among these DEGs, the transcriptional levels involved in the cell wall, sugar and acid metabolism, phenylpropane metabolism, antioxidant enzymes, and WRKY, MYB family transcription factors were significantly regulated. This study will help to promote the application of eugenol for quality improvements in grape berries.

Foliar applications of a Malvaceae-derived protein hydrolysate and its fractions differentially modulate yield and functional traits of tomato under optimal and suboptimal nitrogen application.

Protein hydrolysates (PHs) can enhance plant nitrogen nutrition and improve the quality of vegetables, depending on their bioactive compounds. A tomato greenhouse experiment was conducted under both optimal (14 mM) and suboptimal (2 mM) nitrogen (N-NO3) conditions. Tomatoes were treated with a new Malvaceae-derived PH (MDPH) and its molecular fractions (MDPH1, >10 kDa; MDPH2, 1-10 kDa and MDPH3, <1 kDa). Under optimal N conditions, the plants increased biomass and fruit yield, and showed a higher photosynthetic pigment content in leaves in comparison with suboptimal N, whereas under N-limiting conditions, an increase in dry matter, soluble solid content (SSC) and lycopene, a reduction in firmness, and changes in organic acid and phenolic compounds were observed. With 14 mM N-NO3, MDPH3 stimulated an increase in dry weight and increased yield components and lycopene in the fruit. The MDPH2 fraction also resulted in increased lycopene accumulation in fruit under 14 mM N-NO3. At a low N level, the PH fractions showed distinct effects compared with the whole MDPH and the control, with an increase in biomass for MDPH1 and MDPH2 and a higher pigment content for MDPH3. Regardless of N availability, all the fractions affected fruit quality by increasing SSC, whereas MDPH2 and MDPH3 modified organic acid content and showed a higher concentration of flavonols, lignans, and stilbenes. The molecular weight of the peptides modifies the effect of PHs on plant performance, with different behavior depending on the level of N fertilization, confirming the effectiveness of fractioning processes. © 2024 Society of Chemical Industry.

Differences in analytical methods affect the analytical values of soluble solids, free sugar, and organic acid content of strawberries

The present study compares different pre-treatments used to analyze free sugars and organic acids in strawberries. Soluble solid content, free sugars, and organic acid content in strawberries may vary depending on the pre-treatment methods used for analyze. A comparison of freshly squeezed juice and that obtained post freezing and thawing revealed a significant reduction in sucrose content in the once-frozen juice. However, no significant differences were observed in the soluble solids, glucose, and fructose contents. Furthermore, crushed flesh had significantly higher soluble solid, glucose, and fructose levels and lower sucrose content than those of the juice. Crushed flesh exhibited significantly higher citric acid and a lower malic acid content than those in the juice. There was a significant reduction in sucrose content in the freeze-dried samples compared to all other pre-treatments. Contrastingly, citric and malic acid levels were higher in the freeze-dried samples than that in the freshly crushed samples. The sucrose analytical values can be greatly decrease during the pre-treatment process. Therefore, differences in analytical methods should be considered when comparing sucrose content and composition.

Effects of cofermentation of Saccharomyces cerevisiae and different lactic acid bacteria on the organic acid content, soluble sugar content, biogenic amines, phenol content, antioxidant activity and aroma of prune wine

To determine the effect of cofermentation of Saccharomyces cerevisiae and different LABs on prune wine quality, this study compared phenolic compounds, organic acids, soluble sugars, biogenic amines and volatile flavor compounds among different treatments. The results showed that inoculation of LAB increased DPPH and total flavonoid content. Malic acid content was reduced in HS, HB and HF. Histamine content in S, F and B was lower than the limits in French and Australian wines. 15 phenolic compounds were identified. Yangmeilin and chlorogenic acid were detected only in HS, HF and HB. 51 volatile flavor compounds were identified, esters being the most diverse and abundant. 14 volatile flavor compounds with OAV > 1 contributed highly to the aroma of prune wine. 9 chemical markers including resveratrol, rutin, and catechin were screened to explain intergroup differences by OPLS-DA. This study provides new insights into the processing and quality analysis of prunes.

Enhancing microbial fuel cell performance through microbial immobilization.

Bio-electrochemical Systems (BES), particularly Microbial Fuel Cells (MFC), have emerged as promising technologies in environmental biotechnology. This study focused on optimizing the anode bacterial culture immobilization process to enhance BES performance. The investigation combines and modifies two key immobilization methods: covalent bonding with glutaraldehyde and inclusion in a chitosan gel in order to meet the criteria andrequirements of the bio-anodes in MFC. The performance of MFCs with immobilized and suspended cultures was compared in parallel experiments. Both types showed similar substrate utilization dynamics with slight advantage of the immobilized bio-anode considering thelowerconcentration of biomass. The immobilized MFC exhibited higher power generation and metabolic activity, as well. Probably, this is due to improved anodic respiration and higher coulombic efficiency of the reactor. Analysis of organic acids content supported this conclusion showing significant inhibition of the fermentation products production in the MFC reactor with immobilized anode culture.

NMR Metabolomics of Arctium lappa L., Taraxacum officinale and Melissa officinalis: A Comparison of Spontaneous and Organic Ecotypes.

Officinal plants are a source of metabolites whose chemical composition depends on pedoclimatic conditions. In this study, the NMR-based approach was applied to investigate the impacts of different altitudes and agronomical practices (Land, Mountain Spontaneous, and Organically Grown Ecotypes, namely LSE, MSE, and OE, respectively) on the metabolite profiles of Burdock root, Dandelion root and aerial part, and Lemon balm aerial part. Sugars, amino acids, organic acids, polyphenols, fatty acids, and other metabolites were identified and quantified in all samples. Some metabolites turned out to be tissue-specific markers. Arginine was found in roots, whereas myo-inositol, galactose, glyceroyldigalactose moiety, pheophytin, and chlorophyll were identified in aerial parts. Caftaric and chicoric acids, 3,5 di-caffeoylquinic acid, and chlorogenic and rosmarinic acids were detected in Dandelion, Burdock and Lemon balm, respectively. The metabolite amount changed significantly according to crop, tissue type, and ecotype. All ecotypes of Burdock had the highest contents of amino acids and the lowest contents of organic acids, whereas an opposite trend was observed in Lemon balm. Dandelion parts contained high levels of carbohydrates, except for the MSE aerial part, which showed the highest content of organic acids. The results provided insights into the chemistry of officinal plants, thus supporting nutraceutical-phytopharmaceutical research.

The Effect of Freezing, Frozen Storage and Thawing on the Strawberry Fruit Composition

ABSTRACT Strawberries intended for processing are usually frozen to withstand storage and distribution. However, freezing and thawing can cause the degradation of bioactive compounds. The aim of this study was to determine the optimal conditions for frozen storage and thawing to minimize any loss of nutrients prior processing. Different freezing treatments (−20°C, shock-freezing with liquid nitrogen, −80 °C) up to 6 months of storage and thawing treatments (4°C, room temperature, 37°C, microwave) were compared based on the content of organic acids, sugars, and phenolic compounds as well as the activity of peroxidase and polyphenol oxidase. During frozen storage at −20°C over 6 months, the sucrose content decreased by 59%, but only a 17% loss of ascorbic acid was observed, and no significant loss of anthocyanins was detected. However, more significant changes in composition were detected after thawing. When thawed at 4°C for 24 h, ascorbic acid content decreased by 32%, anthocyanin content by 30%, and sucrose content by 66%. Based on our study, the frozen storage caused smaller changes in the fruit’s composition than thawing. From the thawing procedures, the microwave thawing showed minimal changes in the composition of strawberries.

Fortification of goat milk yogurts with date palm (Phoenix dactylifera L.) coproducts: Impact on their quality during cold storage

The aim of this study was to investigate the impact of different concentrations (3% and 6%) of two ingredients (paste and flour) obtained from the valorization of date fruit coproducts on the nutritional (proximate composition and mineral profile), technological (coagulation curve, pH, acidity, sugar and organic acid content and syneresis), physicochemical (color, water activity and texture), microbiological and sensory properties of goat's yogurt during 21 days of refrigerated storage. Both ingredients enhanced the growth and stability of the yogurt starter culture, thereby improving the probiotic potential of date-added yogurts. Physicochemically, the addition of date flour (at both concentrations) induces stronger modifications (texture, color and syneresis) in yogurts than the date paste. During storage, date paste reduced the syneresis and hence maintained yogurts' physical quality. Consumers preferred the yogurts with date paste (3% and 6%) rather than with date flour, because its addition led to a more brownish color and granular texture.

Quantification of Free Radicals from Vaping Electronic Cigarettes Containing Nicotine Salt Solutions with Different Organic Acid Types and Concentrations.

Electronic (e-) cigarette formulations containing nicotine salts from a range of organic acid conjugates and pH values have dominated the commercial market. The acids in the nicotine salt formulations may alter the redox environment in e-cigarettes, impacting free radical formation in e-cigarette aerosol. Here, the generation of aerosol mass and free radicals from a fourth-generation e-cigarette device was evaluated at 2 wt % nicotine salts (pH 7, 30:70 mixture propylene glycol to vegetable glycerin) across eight organic acids used in e-liquids: benzoic acid (BA), salicylic acid (SLA), lactic acid (LA), levulinic acid (LVA), succinic acid (SA), malic acid (MA), tartaric acid (TA), and citric acid (CA). Furthermore, 2 wt % BA nicotine salts were studied at the following nicotine to acid ratios: 1:2 (pH 4), 1:1 (pH 7), and 2:1 (pH 8), in comparison with freebase nicotine (pH 10). Radical yields were quantified by spin-trapping and electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra of free radicals in the nicotine salt aerosol matched those generated from the Fenton reaction, which are primarily hydroxyl (OH) radicals and other reactive oxygen species (ROS). Although the aerosol mass formation was not significantly different for most of the tested nicotine salts and acid concentrations, notable ROS yields were observed only from BA, CA, and TA under the study conditions. The e-liquids with SLA, LA, LVA, SA, and MA produced less ROS than the 2 wt % freebase nicotine e-liquid, suggesting that organic acids may play dual roles in the production and scavenging of ROS. For BA nicotine salts, it was found that the ROS yield increased with a higher acid concentration (or a lower nicotine to acid ratio). The observation that BA nicotine salts produce the highest ROS yield in aerosol generated from a fourth-generation vape device, which increases with acid concentration, has important implications for ROS-mediated health outcomes that may be relevant to consumers, manufacturers, and regulatory agencies.

Influence of organic acids on the viscosity and rheological behavior of guar gum solution

The present study aims to determine the influence of four edible organic acids (ascorbic, citric, malic, and tartaric) at two concentrations (0.5, and 1 %) on the viscosity and rheological behavior of guar gum dispersion (0.2 %, w/v). The finding of this study revealed that the apparent viscosity of guar gum dispersions reduced when the shear rate increased. Additionally, the apparent viscosity of the guar gum dispersions reduced as the organic acids concentration increased from 0 to 1 %. The highest decrease in viscosity was related to 1 % ascorbic acid and the lowest was related to 0.5 % malic acid. The rheological behavior of dispersions were successfully modeled using Power law, Bingham, Herschel-Bulkley, and Casson models, and the Power law model was the best one for describing the behavior of guar gum dispersions containing organic acids. The Power law model showed good performance with the maximum r-value (mean = 0.9988) and least sum of squared error (SSE) values (mean = 0.0021) and root mean square error (RMSE) values (mean = 0.0119) for all samples. The consistency coefficient (k-value) values of the samples (Power law and Herschel-Bulkley models) reduced as the acid percent was increased. The sample containing 1 % tartaric acid had the lowest k-value and the sample containing 0.5 % ascorbic acid had the highest k-value. The flow behavior index (n-value) (Power law and Herschel-Bulkley models) of the samples increased when the acid percent was increased. In summary, the use of guar gum in food products containing high concentrations of tartaric and ascorbic acids is not recommended.