Acidic pH Values Research Articles

Utilization of Indigenous Microorganisms (IMO) on Lactic Acid Content, pH Value, Dry Matter, and Fleigh Value of Anaerobic Fermentation Cassava Skin (Manihot esculenta)

The purpose of this study was to determine the effect of using Indigenous Microorganisms( IMO) based on soybean cooking water, rice washing water, tofu dregs water, rumen contents liquid, and coconut water as a commercial starter to replace EM4 in the manufacture of fermentation based on the value of lactic acid content, the value of pH, dry matter content, and Fleigh value. This research was conducted at the Laboratory of Animal Husbandry and Fisheries Technology, Faculty of Agriculture, Tidar University. The research method used a completely randomized design with four treatments (P0 = Cassava peel + EM4 (1%) + molasses (3%), (P1 = Cassava peel + IMO 1 (1%) + molasses (3%), (P2 = Cassava peel + IMO 2 (1%) + molasses (3%), (P3 = Cassava peel + IMO 3 (1%) + molasses (3%) and five replications. The data obtained were analyzed using ANOVA and Dunnet's test, using the IBM SPSS 21 tool. The results of this study showed that the use of MOL had a significant effect (P<0.05) on pH but had no significant effect (P>0.05) on lactic acid , dry matter content, and Fleigh value. The conclusion of this study is that the use of MOL can be used as a substitute for a commercial starter because the anaerobic fermentation of cassava peels produced is included in the very good category based on the pH value, lactic acid content, dry matter and the resulting Fleigh value.

Investigations into the stability of anthocyanins in model solutions and blackcurrant juices produced with various dejuicing technologies

Blackcurrant juices were produced with an oxygen-excluding spiral filter press and two conventional pressing systems exerting common oxygen exposure at pilot plant scale (200 kg) in technological duplicate in two subsequent years (n = 4). In contrast to findings on previously studied fruits, contents of total and individual anthocyanins were not significantly higher after spiral filter (1636–1872 mg/L) than after conventional pressing (1529–2083 mg/L). During storage for 52 weeks at 4, 20 and 37 °C, anthocyanin levels depended strongly on storage temperature, but not on the used pressing system (conventional vs. oxygen-reduced). Other juice quality parameters like ascorbic acid behaved likewise. Furthermore, a D-optimal design of experiments was used to study the influence and interactions of the factors oxygen, ascorbic acid, sugar and pH value on anthocyanin levels during a heat treatment in a model solution made with preparatively isolated blackcurrant anthocyanins. In agreement with our production trials at pilot plant scale, oxygen levels were only marginally important for the rate of anthocyanin degradation, but the influence of sugar content, ascorbic acid content and pH value was highly relevant as discussed in this report.

Activation of periodate with pinewood biochar-CuO composite for the removal of recalcitrant organic pollutants – Mechanisms and degradation products

The degradation kinetics and mechanisms of various types of recalcitrant organic pollutants (ROPs) by a novel biochar-CuO (B-CuO)/periodate (PI) system have been deeply investigated in the present study. More precisely, the study aimed to explore the significant effects of pH on the formation of various oxidative species using this treatment system. According to the results achieved, iodate (IO3∙) and periodate radicals (IO4∙), ∙OH and O(3P) were mostly generated at pH ≈ 7, resulting in the efficient removal of methylene blue (MB) (90% after 30 min, kobs = 0.09 min−1), while the system favoured the formation of O(3P) under highly alkaline pH values (pH = 11), leading to lower degradation kinetics of the pollutant (51% after 30 min, kobs = 0.028 min−1). Additionally, no oxidative species were found at highly acidic pH values (pH = 3), and no significant MB removal was observed (21% after 30 min, kobs = 0.0081 min−1). Elevating the temperature (from 25 °C to 80 °C) and bubbling with nitrogen or oxygen gas also did not have any significant effects on the degradation of ROPs. Additionally, the system maintained its efficiency in various water matrices, including real wastewater, confirming the applicability of the biochar-CuO/PI system for real water treatment processes. The system also exhibited a high degradation efficiency for other types of ROPs, such as ciprofloxacin. Experiments using ultra-high performance liquid chromatography in combination with quadrupole time-of-flight mass spectrometry were performed to identify the degradation products and pathways of MB, revealing the contribution of two different degradation pathways and the formation of five degradation products in the B-CuO/PI system. The ECOSAR program was employed to evaluate the predicted toxicity of the degradation products. The results showed that the system could efficiently detoxify MB.

Immobilization of Aspergillus sp. laccase on hierarchical silica MFI zeolite with embedded macropores

Laccase from Aspergillus sp. (LC) was immobilized on functionalized silica hierarchical (microporous-macroporous) MFI zeolite (ZMFI). The obtained immobilized biocatalyst (LC#ZMFI) was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (ATR-FTIR), N2 adsorption/desorption isotherms, solid-state NMR spectroscopy and thermogravimetric analysis (TGA) confirming the chemical anchoring of the enzyme to the zeolitic support. The optimal pH, kinetic parameters (KM and Vmax), specific activity, as well as both storage and operational stability of LC#ZMFI were determined. The LC#ZMFI KM and Vmax values amount to 10.3 µM and 0.74 µmol·mg−1 min−1, respectively. The dependence of specific activity on the pH for free and immobilized LC was investigated in the pH range of 2–7, The highest specific activity was obtained at pH = 3 for both free LC and LC#ZMFI. LC#ZMFI retained up to 50 % and 30 % of its original activity after storage of 21 and 30 days, respectively. Immobilization of laccase on hierarchical silica MFI zeolite allows to carry out the reaction under acidic pH values without affecting the support structure.

Quantitative separation of thorium from rare earth elements and uranium in a rare earth element sulfuric acid leachate using cloud point extraction

A new cloud point extraction (CPE) method was created for extracting and concentrating thorium from a sulfuric acid leachate of rare earth elements (REESL). The method employs P,P′-di(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP]) as a chelating agent that has a strong attraction for actinides. By using Triton X-100 as a non-ionic surfactant and cetyl trimethyl ammonium bromide (CTAB) as an ionic surfactant, thorium is quantitatively extracted (over 98%) into a small volume of the surfactant-rich phase through heating and centrifugation. The method is based on in situ bromine formation to improve phase separation at highly acidic pH values resulting from the leaching steps. The method yielded a preconcentration factor of 22 when tested on REESL. To our knowledge, it is the first paper dealing with the use of CPE to selectively separate Th(IV) from rare earth elements and U from mining leachates.

Effect of microbial transglutaminase on thermal stability of milk protein

At present, Transglutaminase (abbreviated as TG, EC2.3.2.13) has been used in meat products, dairy products and baked goods in Japan and other countries. The stability of MP (Milk protein) colloid system is very important to the quality of dairy products. The effect of MTG (Microbial TG) on the thermal stability of MP was studied in this experiment. The change of HCT (Heat Coagulation Time) of MP emulsion before and after adding MTG was measured. The results show that the effect of MTG on MP leads to the decrease of its solubility in the region of pH < 4.0 or pH > 7.0, but it increases in the range near the isoelectric point of MP (pH 4.0 ~ 6.0). In the range of acidic pH value with low stability, the high calcium ion activity, low Zeta potential and micelle hydration make the milk have poor thermal stability and will solidify rapidly at 150℃. The hydrophobic interaction between MTG and MP changes the conformation of MP, which leads to the change of thermal stability.

A new bacterial-derived biosurfactant for biotechnological applications in the oil industry: production, optimization, biosurfactant functional and physicochemical characterization

Abstract Aiming the potential application of lipopeptide biosurfactant (BioS) in bioremediation, we studied its production by a novel, isolated strain of Bacillus sp. MI27. Using the experimental design methodology, a novel medium composed of 2% sucrose, 0.27% Na2HPO4, 0.2% ammonium sulfate, 0.02% NaCl, 0.02% CaCl2, 0.02% MgSO4, 0.001% MnSO4, 0.06% KH2PO4, 0.005% FeSO4 and 0.005% ZnSO4 was optimized. With this composition, strain MI27 produces 1.4 g/L BioS with maximum surface tension (ST) reduction of 23 mN/m and a dispersion diameter of around 10 cm. Emulsifying and foaming activities have been also confirmed. The critical micelle concentration (CMC) value was about 120 mg/L with corresponding ST of 23 mN/m. The dispersion and emulsification index (EI) were about 12 cm and 45% at 1,000 mg/L respectively. Moreover, the foaming capacity, stable over 1 h of incubation, was about 80% at 1,000 mg/L. Additionally, we studied the effect of different pH, temperature and salinities on MI27 BioS activity and stability. Obtained results showed interesting surface activities at extreme physicochemical conditions, especially at acidic and alkaline pH values, high and low temperatures and higher salinities. All these characteristics enable the possible application of BioS in water treatment biotechnology under diverse environmental conditions.

How do the skin barrier and microbiome adapt to the extra-uterine environment after birth? Implications for the clinical practice.

The multiple protective functions of the skin derive from the interactions between epithelial skin and immune cells as well as the commensal microbiota. Developed in the last trimester of intra-uterine life, the skin barrier adapts dynamically after birth. Specific differences in the structure and physiology have been disclosed between infant and adult skin. The stratum corneum of infants is thinner and structured by thicker corneocytes with a more anisotropic surface in comparison to adult skin. Lower levels of the natural moisturizing factor and its constituents, together with the increased protease activity in the epidermis result in dry baby skin and ongoing adaptation of the desquamation to the extra-uterine environment. Infant epidermis is characterized by an accelerated proliferation rate and clinically competent permeability barrier in term neonates, despite the higher baseline values of transepidermal water loss in infants. The skin surface of newborns is less acidic, which could increase susceptibility to diaper and atopic dermatitis. Immediately after birth, skin is colonized by commensal bacteria-a process dependent on the mode of delivery and of major importance for the maturation of the immune system. Skin bacterial diversity and dysbiosis have been related to different pathology such as atopic and seborrheic dermatitis. This paper focuses on the ongoing structural, functional and biochemical adaptation of the human skin barrier after birth. We discuss the interactions on the 'skin barrier/ microbiota/ immune system' axis and their role in the development of competent functional integrity of the epidermal barrier.

Lignocellulolytic enzyme cocktail produced by plant endophytic Chaetomium globosum exhibits a capacity for high-efficient saccharification of raw rice straw

The aim of this work was to optimize the production of lignocellulolytic enzyme cocktail by a plant endophyte Chaetomium globosum DX-THS3 under solid-state fermentation, and to evaluate the saccharification efficiency of this enzyme cocktail on raw rice straw. The process variables, including substrate type, substrate size, initial moisture content of substrate, culture temperature and fermentative time, were optimized using One-factor at a time approach and Response surface methodology. The results showed that the maximum CMCase, FPase and xylanase production reached 237.04 U/g, 54.8 U/g, and 987.33 U/g, respectively. Meanwhile, the lignocellulolytic enzyme cocktail exhibited good thermal stability between 30 °C and 60 °C, and excellent tolerance to acidic pH values of 3–6. Subsequently, the saccharification of raw rice straw by the enzyme cocktail was performed. After 24 h hydrolysis of raw rice straw, high reducing sugars yield (294.36 mg/g) and hydrolytic rate (47.58 %) were achieved. Furthermore, scanning electron micrograph also indicated that the enzyme cocktail had high hydrolysis performance for raw rice straw. Overall, our result provides a novel class of lignocellulolytic enzyme cocktail with a capacity for high-efficient and eco-friendly saccharification of raw rice straw, and strongly suggests plant endophytic fungi as excellent candidates for the production of lignocellulolytic enzymes.

A Study on Mechanisms Underlying Proton Transport in Proton Pump-type Microbial Rhodopsins

Microbial rhodopsins are photoreceptive membrane proteins composed of seven transmembrane α-helical apoproteins (opsin) and a covalently bound retinal chromophore. Microbial rhodopsins exhibit a cyclic photochemical reaction referred to as photocycle when illuminated. During their photocycles, these proteins perform various functions such as ions transport and photosensing. Among the various functional types of rhodopsins found to date, we have focused on the utility of proton pump-type microbial rhodopsins as optogenetic tools for optical pH control in cells or organelles. To develop effective toolkits for this purpose, a deeper understanding of the proton-pumping mechanism in these rhodopsins may be required. In this review, we first introduce a useful experimental method for measuring rapid transient pH changes with photoinduced proton uptake/release using transparent tin oxide (SnO2) or indium-tin oxide (ITO) electrodes. In addition, we describe the unique pH-dependent behavior of the photoinduced proton transfer sequence as well as the vectoriality of proton transportation in proteorhodopsin (PR) from marine eubacteria. Through intensive ITO experiments over wide pH range, including extremely high or low pH values, in combination with photoelectric measurements using Xenopus oocytes or a thin polymer film "Lumirror," we encountered several interesting observations on photoinduced proton transfer in PR:1) proton uptake/release sequence reversal and potential proton translocation direction reversal under alkali conditions, and 2) fast proton release from D227, a secondary counterion of the protonated retinal Schiff base at acidic pH values.

Geochemistry and geostatistics for the assessment of trace elements contamination in soil and stream sediments in abandoned artisanal small-scale gold mining (Bétaré-Oya, Cameroon)

Soil and stream sediment contamination from abandoned artisanal mines is of prime importance due to the associated potential for heavy metal and metalloid contamination. Indeed, mine wastes are an evident source of soil and stream sediment contamination. The aim of the current study is to propose a conceptual approach to assess the contamination degree and the spatial distribution of trace elements in soils and stream sediments around mine sites. The abandoned artisanal gold mine of Bétaré-Oya in Cameroon was considered as a case study. In order to separate anthropogenically contaminated soils and stream sediments from the un contaminated ones, representative soil, stream sediment and mine wastes samples were collected and analyzed for the pH, Electrical Conductivity (EC), mineralogical paragenesis, major elements and trace elements. Very acidic pH values and high EC values ranging from 3.2 to 5.8 and from 44 to 315 μs cm−1, respectively were obtained for the analyzed samples. Based on the enrichment factor (EF) calculation, four elements of interest (Co, Cd, Cu and As) were selected for soils and seven elements of interest (Co, Cd, Cu, As, Cr, Pb and Zn) were selected for stream sediments. The Geochemical Background (GB) of these elements was determined with the normal Q-Q plot, the Geo-accumulation index (Igeo) was calculated and the geochemical maps for soils and stream sediments were elaborated using geostatistics in Geographic Information System (GIS) environment.The obtained results show that Bétaré-Oya soils and stream sediments are contaminated with metals and metalloid that exceed the established GB values for soil (Co ≈ 17.73 mg/kg, Cd ≈ 0.36 mg/kg, Cu ≈ 146.81 mg/kg and As≈48.82 mg/kg) and GB values for stream sediments (Co ≈ 30.90 mg/kg, Cd ≈ 0.24 mg/kg, Cu ≈ 173 mg/kg, As≈51.59 mg/kg, Cr ≈ 137 mg/kg, Pb ≈ 7.56 mg/kg, and Zn ≈ 39.48 mg/kg). The Igeo calculation revealed that soils and stream sediments were highly influenced by anthropogenic activity. The maximum values of the Igeo, especially for Cd ≈ 4.59, Pb ≈ 2.83, and Zn ≈ 2.97, highlighted the highly contaminated samples and therefore quantify accurately the contamination degree. Finally, geochemical maps of soils and stream sediments show clearly that mine wastes are the main source of trace elements contamination in the study area.

Improving the sustainability of heterogeneous Fenton-based methods for micropollutant abatement by electrochemical coupling

Advanced oxidation processes such as Fenton reaction-based processes have attracted great interest in recent years as a promising alternative for the removal of persistent pollutants in wastewater. The use of nanocatalysts in advanced oxidation processes overcomes the limitations of homogeneous Fenton processes, where acidic pH values are required, and a large amount of sludge is generated after treatment. Aiming at maximizing the catalytic potential of the process, different configurations include coupling photocatalysis or electrochemistry to Fenton reactions. This manuscript presents a comparative environmental and economic analysis of different heterogeneous Fenton-based process using magnetic nanoparticles: Fenton, photo-Fenton, electro-Fenton and photoelectron-Fenton. These alternatives encompass not only different reaction conditions but also varying degradation kinetics, which control the treatment capability in each specific case. It is not only important to determine the technological feasibility of the proposal based on the removal performance of the target compounds, but also to identify the environmental profile of each configuration. In this regard, the Life Cycle Assessment methodology was applied considering a combination of primary and secondary data from process modeling. Moreover, and aiming towards the future large-scale implementation of the technology, an economic analysis of each configuration was also performed to provide a better understanding about the costs associated to the operation of Fenton-based wastewater treatments.

PH-Selective Reactions to Selectively Reduce Cancer Cell Proliferation: Effect of CaS Nanostructures in Human Skin Melanoma and Benign Fibroblasts.

An acidic extracellular pH value (pHe) is characteristic of many cancers, in contrast to the physiologic pHe found in most benign cells. This difference in pH offers a unique opportunity to design and engineer chemicals that can be employed for pH-selective reactions in the extracellular fluid of cancer cells. The viability of human skin melanoma and corresponding fibroblasts exposed to CaS dispersions is reported. The viability of melanoma cells decreases with CaS dispersion concentration and reaches 57% at 3%, a value easily distinguishable from melanoma control experiments. In contrast, the viability of benign fibroblasts remains nearly constant within experimental error over the range of dispersion concentrations studied. The CaS dispersions facilitate vinculin delocalization in the cytoplasmic fluid, a result consistent with improved focal adhesion kinase (FAK) regulation in melanoma cells. Thermodynamic considerations are consistent with the formation of from CaS in the presence of protons. The thermodynamic prediction is verified in independent experiments with solid CaS and acidic aqueous solutions. The amount of formed decreases with pH. An activation energy for the process of (30 ± 10) kJ/mol in the temperature range of 280 to 330 K is estimated from initial rate measurements as a function of temperature. The total Gibbs energy minimization approach was employed to establish the distribution of sulfides-including in the gas and aqueous phases-from the dissociation of CaS as a function of pH to mimic physiologically relevant pH values. Theoretical calculations suggest that partially protonated CaS in solution can be stable until the sulfur atom bonds to two hydrogen atoms, resulting in the formation of Ca2+ and , which can be solvated and/or released to the gas phase. Our results are consistent with a model in which CaS is dissociated in the extracellular fluid of melanoma cells selectively. The results are discussed in the context of the potential biomedical applications of CaS dispersions in cancer therapies.

GPCR Signaling Measurement and Drug Profiling with an Automated Live-Cell Microscopy System.

A major limitation of time-lapse microscopy combined with fluorescent biosensors, a powerful tool for quantifying spatiotemporal dynamics of signaling in single living cells, is low-experimental throughput. To overcome this limitation, we created a highly customizable, MATLAB-based platform: flexible automated liquid-handling combined microscope (FALCOscope) that coordinates an OpenTrons liquid handler and a fluorescence microscope to automate drug treatments, fluorescence imaging, and single-cell analysis. To test the feasibility of the FALCOscope, we quantified G protein-coupled receptor (GPCR)-stimulated Protein Kinase A activity and cAMP responses to GPCR agonists and antagonists. We also characterized cAMP dynamics induced by GPR68/OGR1, a proton-sensing GPCR, in response to variable extracellular pH values. GPR68-induced cAMP responses were more transient in acidic than neutral pH values, suggesting a pH-dependence for signal attenuation. Ogerin, a GPR68 positive allosteric modulator, enhanced cAMP response most strongly at pH 7.0 and sustained cAMP response for acidic pH values, thereby demonstrating the capability of the FALCOscope to capture allosteric modulation. At a high concentration, ogerin increased cAMP signaling independent of GPR68, likely via phosphodiesterase inhibition. The FALCOscope system thus enables enhanced throughput single-cell dynamic measurements and is a versatile system for interrogating spatiotemporal regulation of signaling molecules in living cells and for drug profiling and screening.

Monitoring and PH Analysis of Tailings from the Effluents of the Cerro De Pasco Mining Company in the Years 2017-2021

Currently, mining operations in Peru, such as in the province of Pasco, require water consumption for metallurgical mining processes, supply for personnel, among other operations. The purpose of this study is to determine whether the mining company located in Cerro de Pasco has reduced its pH values over the years and whether they are within the Maximum Permissible Limits established by Peru. The impacts of mining activities cause damage to water bodies and the health of the population, so water monitoring is carried out at certain discharge points called cell1, cell2 and cell3, where pH measurements were taken. The results of the monitoring, with respect to the tailings from the mine, are acidic pH values containing suspended solids as well as high concentrations of sulphates and metals. The contributions of the study, which is carried out in the city of Cerro de Pasco located at 4338 m.a.s.l., show practical results as they are used for a diagnosis and analysis for the years 2017-2021 with respect to the mine tailings.

Natural calcium phosphates from circular economy as adsorbent phases for the remediation of textile industry waste-waters

Adsorption is one of the most important techniques for the remediation of textile industry wastewaters containing high concentrations of toxic dyes. Calcium phosphates (CaPs) have been advocated among the most promising adsorbent phases in virtue of their high dye adsorption potential, low production cost, and possible recovery from circular economy sources. In this paper, we investigated the application of synthetic CaPs (CaP–S) and two CaPs extracted from food by-products, namely from bone meal (CaP-BM) and fish bones (CaP-FM) for the removal of a model dye, copper phthalocyanine tri-sulfonic acid, also known as acid blue 185 (AB-185). All the materials were characterized from the physical-chemical point of view and used for the study of adsorption kinetic and isothermal adsorption of AB-185 at neutral, acidic and basic pH values. The best adsorption capacity was obtained for CaP–S, followed by CaP-BM and CaP-FM. Nonetheless, results showed that all the materials can be employed for removing AB-185 from wastewaters of textile industry, and we correlated dye removal efficiency to the adsorbent phase specific surface area (SSA) and ζ-potential, as well as to dye concentration and pH of wastewaters. Finally, as the process used to produce the studied CaPs affects their main final physical-chemical parameters and performance in terms of dyes removal, it is important to consider the variables of CaPs production process (e.g., temperature, time of treatment, grinding etc.), especially when CaPs are recovered from circular economy sources by thermal treatments of food-byproducts.

One-step synthesis of a pH switched pyrene-based fluorescent probe for ratiometric detection of HS- in real water samples.

Only a few probes are suited for highly acidic environments and sensitive to pH values below 4. Thus, finding a solution for detecting strong acidic (pH value below 2) conditions is still challenging. Herein, we constructed and created a pH-switched fluorescent probe based on pyrene and a heteroatom containing pyridine unit. When exposed to acidic environments (pH 2.0), the probe's fluorescence redshifted with distinct colour and fluorescence changes owing to protonation on the nitrogen atom containing pyridine moiety, which could be deprotonated by HS- selectively compared to other competing analytes. Pyr can detect HS- with a rapid response within 5 s and showed very good quantum yield under acidic environments. The sensing mechanism was confirmed by Density Functional Theory (DFT) studies using the B3LYP and 6-31G+ (d) basis sets. Furthermore, the probe was utilized to monitor HS- in actual water samples and identify H2S gas by a simple paper strip test.

Selective recognition of neurotransmitters in aqueous solution by hydroxyphenyl aza-scorpiand ligands.

The synthesis, acid-base behaviour and anion recognition of neurotransmitters (dopamine, tyramine and serotonin) in aqueous solution of different aza-scorpiand ligands functionalized with hydroxyphenyl and phenyl moieties (L1-L3 and L4, respectively) have been studied by potentiometry, NMR, UV-Vis and fluorescence spectroscopy and isothermal titration calorimetry (ITC). The analysis of the potentiometric results shows the selective recognition of serotonin at physiological pH (Keff = 8.64 × 104) by L1. This selectivity has an entropic origin probably coming from a fine pre-organization of the interacting partners. Thus, the complementarity of the receptor and the substrate allows the reciprocal formation of hydrogen bonds, π-π and cation-π interactions, stabilizing the receptors and slowing the rate of oxidative degradation, and satisfactory results are obtained at acidic and neutral pH values. NMR and molecular dynamics studies reveal the rotation blockage in the neurotransmitter side chain once complexed with L1.

The Use of Flavylium Salts as Dynamic Inhibitor Moieties for Human Cb5R

Cytochrome b5 reductase (Cb5R) is a flavoprotein that participates in the reduction of multiple biological redox partners. Co-localization of this protein with nitric oxide sources has been observed in neurons. In addition, the generation of superoxide anion radical by Cb5R has been observed. A search for specific inhibitors of Cb5R to understand the role of this protein in these new functions has been initiated. Previous studies have shown the ability of different flavonoids to inhibit Cb5R. Anthocyanins are a subgroup of flavonoids responsible for most red and blue colors found in flowers and fruits. Although usually represented by the flavylium cation form, these species are only stable at rather acidic pH values (pH ≤ 1). At higher pH values, the flavylium cation is involved in a dynamic reaction network comprising different neutral species with the potential ability to inhibit the activities of Cb5R. This study aims to provide insights into the molecular mechanism of interaction between flavonoids and Cb5R using flavylium salts as dynamic inhibitors. The outcome of this study might lead to the design of improved specific enzyme inhibitors in the future.

Effect of Pink Rock Rose Extract with or Without Ascorbic Acid and Sodium Ascorbate for the Preservation of Ready-to-Eat Frankfurter Type Sausages

This study aimed to determine the effect of pink rock rose extract (PRR) with or without ascorbic acid and sodium ascorbate for improving the shelf life of sausages. Analyzed parameters were DPPH radical scavenging capacity of PRR extract; total aerobic count, thiobarbituric acid reactive substance, heme iron, pH, water activity, proximate composition, and color values of MAP packaged sausages for 12 weeks at 4 °C. Treatments: (1) Control (0.02% ascorbic acid and 0.05% sodium ascorbate – AA-SA), (2) electrostatic spray application of PRR extract (2%) – ES-PRR, (3) 0.02% AA and, 0.05% PRR extract, (4) 0.05% SA and 0.02% PRR, (5) 0.07% PRR extract. PRR extract had the half maximal inhibitory concentration (IC50) value of 13.04 ± 0.133 µg/mL. Sausages formulated with 0.07% PRR had the lowest microbial growth rate, followed by AA-PRR formulation. The AA-PRR treatment had the lowest TBARS values for most of the storage. This study reveals that PRR extract can be added as a natural antioxidant in sausages, and it could be used as a replacement or for the reduction of ascorbic acid and sodium ascorbate in sausage formulations.