Decrease In pH Research Articles

Effect of Pre-Emulsified Flaxseed Oil Containing Rutin on the Quality of Nemipterus virgatus Surimi Gel: Gelatinization Properties, Storage Stability, and Protein Digestibility

Rinsing during surimi protein processing can result in the loss of essential nutrients, such as fats and minerals. Therefore, supplementing functional fats in a stable form can make up for the fat loss of surimi during the rinsing process. This research aimed to investigate the effects of incorporating pre-emulsified flaxseed oil with different concentrations of rutin (0, 0.5, 1.5, 2.5, and 3.5%, dissolved in flaxseed oil, w/v) to Nemipterus virgatus surimi on the gelatinization properties, lipid oxidation, and in vitro static simulated digestion characteristics of surimi gels. The results indicated that the addition of 1.5% rutin significantly improved the water-holding capacity and decreased the cooking loss rate of surimi gel (p < 0.05). The results of optical microscopy and scanning electron microscopy showed that the addition of 1.5% rutin promoted a denser network structure of surimi gel. Furthermore, the incorporation of rutin effectively slowed lipid oxidation in pre-emulsified flaxseed oil surimi gel. Compared with the gel group containing only pre-emulsified flaxseed oil, the addition of rutin significantly reduced the levels of volatile base nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARSs) in the gel and also mitigated the decline in acidity (p < 0.05). Moreover, the addition of rutin significantly inhibited the decrease in pH of surimi gel during storage (p < 0.05). In vitro static simulated digestion demonstrated that the addition of 1.5% rutin enhanced the protein digestibility from 71.2% to 77.2% of the surimi gel. Therefore, adding pre-emulsified oil containing an appropriate amount of rutin to surimi can not only compensate for the fat loss during the surimi rinsing process but also effectively improve the quality characteristics of surimi gels. This research will provide a theoretical basis for the effective addition of functional lipids in surimi products and the development of nutritious and healthy surimi products.

The role of biotribocorrosion in the development and progression of clinical manifestations of pseudomembranous candidiasis

Objective. To establish the effect of biotribocorrosion on the development and chronic course of pseudomembranous candidiasis. Materials and methods. The study was conducted at the Department of Orthopedic Dentistry and Gnatology and at the Department of Propaedeutics of Orthopedic Dentistry of the Russian University of Medicine. The study involved 80 patients with pseudomembranous candidiasis using metal dentures and 40 patients with pseudomembranous candidiasis without metal-containing structures, who made up the control group. All participants in the study measured the difference in oral biopotentials, hydrogen index, and salivation rate. Results. In patients of the main group, the content of Fe, Cr, Ni, Ti, Si, K, Na in saliva was significantly increased (p < 0.05) compared with the control group. It was found that dissimilar metal alloys have different effects on the duration of use of dentures. In pseudomembranous candidiasis and the presence of metal-containing structures with signs of biotribocorrosion, a more pronounced electrochemical reaction of stainless steel coated with titanium nitride and uncoated significantly reduces the life of dentures (from 3 to 5 years), compared with CCC metal-ceramic prostheses (from 2 to 10 years) and Ni-Cr-Ni-Cr (from 5 to 8 years old). The greatest pH shift to the acidic side is observed with a combination of stainless steel and Ni-Cr prostheses (pH 5.5–6.0). In pseudomembranous candidiasis, patients using metal dentures have the highest potential differences between M-M. Conclusions. Due to tribocorrosion, corrosion products enter the oral fluid, under their influence, a decrease in pH occurs, provoking a weakening of the protective properties of saliva, a violation of metabolic processes and structural changes in the oral mucosa. Thus, there is a favorable environment for the growth of fungi of the genus Candida, inflammation of the oral mucosa occurs. Microbial flora and fungi that stimulate the development of the inflammatory process are localized in inflammatory areas.

Removal of Tetracycline Antibiotic as a Hospital Waste by pH‐Sensitive Degradable Composite Hydrogel Using Fenton‐Like System

ABSTRACTFenton‐like hydrogels crosslinked with imine bond were prepared for the removal of tetracycline. Initially, the oxidation process of carboxymethyl cellulose (CMC) was performed, and it was named OX‐CMC. The confirmations were then obtained using NMR and FTIR analyses. The degree of CMC oxidation was investigated in relation to reaction time, and optimal time of 4 h was selected. In the second part, a pH‐sensitive hydrogel with imine bond was prepared from the crosslinking reaction between OX‐CMC and chitosan. The formation of the hydrogel through imine crosslinking was confirmed by FTIR spectroscopy. By increasing ratio of OX‐CMC to chitosan, the swelling rate for the hydrogel decreased. Turbidity measurements showed that a higher OX‐CMC to chitosan weight ratio resulted in slower hydrogel degradation in acidic environments. In the third part, Fe3O4 nanoparticles with concentrations of 5 and 10 wt% were incorporated into the hydrogel structure. TEM studies revealed a spherical morphology and uniform distribution of nanoparticles within the hydrogel network. SEM images revealed a porous structure which composed of interconnected pores in the hydrogel. The results of UV–visible spectroscopy indicated that the degradation of magnetic hydrogels would augment as magnetic nanoparticle content increases, pH decreases, and the hydrogen peroxide content increases.

Efficiency of Phragmites australis (Cav.) Trin. Ex Steud. and Typha latifolia L. in remediating methyldiethanolamine (MDEA) from Ilam gas refinery wastewater: Isotherm and kinetic studies.

This study presents a novel, eco-friendly method for removing methyldiethanolamine (MDEA) from wastewater, addressing its environmental impact and elevated chemical oxygen demand (COD) from gas refineries. We employed two wetland plants, Phragmites australis and Typha latifolia, utilizing a hydroponics approach to assess MDEA removal efficiency. Wastewater samples from the Ilam gas refinery in Iran were tested at varying initial concentrations (50 to 1600ppm) over three consecutive 7-day periods, with a 1-day rest interval. Key factors influencing MDEA absorption-contact time, initial effluent concentration, and pH-were systematically analyzed. Results indicated a significant decrease in pH, COD, and MDEA concentration during the first four days. Kinetic modeling employed pseudo-first-order (PFO) and pseudo-second-order (PSO) models, alongside adsorption isotherms (Langmuir, Freundlich, Temkin, Dobinin-Radeshkovich, and Louis), to evaluate MDEA absorption capacity. The Langmuir isotherm best described the absorption characteristics of both plants. Maximum adsorption capacities were recorded for P. australis at 1.181, 2.018, and 3.77mg/L across the experimental periods, while T. latifolia showed values of 0.779, 1.099, and 2.99mg/L. Kinetic analysis favored the pseudo-second-order model for both species. Our findings suggest that P. australis is the more effective candidate for phytoremediation of MDEA in wastewater treatment applications.

Dissolved beryllium (< 1 kDa) mobilized as a major element in groundwater in legacy mine waste.

Research regarding the geochemistry of beryllium (Be) in terrestrial environments is hindered by its high toxicity to humans and the low concentrations normally occurring in the environment. Although Be is considered an immobile element, extremely high dissolved concentrations have been detected in groundwater in the legacy Tailings Storage Facility (TSF) of Smaltjärnen, Sweden. Therefore, a detailed study was conducted to determine physiochemical parameters affecting the speciation of Be in the groundwater. Groundwater was sampled from 2016-2024 and filtered through 0.2 μm filters, whereas truly dissolved fraction (<1 kDa) samples were collected with dialysis membrane tubes in situ at groundwater wells. Secondary minerals on the tailings shore were studied by mineralogical methods and sequential extraction to trace the pathway whereby Be entered the downstream surface water. In part of the tailings, dissolved Be was detected in very high concentrations (average: 4.8 mg/L) in suboxic groundwater with pH from 6.0 to 6.4. Dialysis sampling in 2024 showed that more than 90% occurred as truly dissolved Be (<1 kDa). A significant correlation between Be and S was found, suggesting that sulfate complexes kept Be mobile in these pH conditions. Dissolved Be increased with decreased pH, and there is risk that the concentrations will increase further since sulfide oxidation with subsequent decrease in pH will continue for 100 of years in the TSF. In another part of the TSF, the pH was > 6.4 and dissolved Be was below the detection limit, possibly due to formation of Al(OH)3 (>0.2 μm) together with F and Zn. Secondary minerals on the shore of the tailings functioned as a temporary chemical barrier, scavenging Be primarily by secondary gypsum when present and otherwise by Fe hydr(oxides).

Presence of Humic Acids in Landfill Leachate and Treatment by Flocculation at Low pH to Reduce High Pollution of This Liquid

Humic substances are abundant in landfill leachate, especially humic acids, which are insoluble at low pH in aqueous solutions. Focusing on the chemical properties of humic acids, we describe in this work a new method for a sustainable treatment of landfill leachate originated from solid wastes, which consists of the reduction of organic load (COD, chemical oxygen demand) and colour and is based in the gradual decrease in pH to the value in which HAs are insoluble in water solution. Zeta potential values mark the chemical stage of humic acids because of ionisation–protonation of the phenolic and carboxylic groups, and this parameter is monitored during flocculation, changing from −16.8 mV at pH 7.7 to 0.0068 mV at pH 2.0, when HAs precipitate. The final result is the reduction in the organic matter content (COD) and colour in the leachate, 86.1% and 84.7%, respectively. Solids produced by precipitation during the acidification treatment have been characterized by elemental chemical analysis and Fourier transform infrared spectrometry, concluding a high similarity in chemical composition with commercial and natural humic acids. Protonated humic acids at low pH can interact with other molecules by hydrogen bonds and form bigger molecular structures much more unstable in suspension, which conduct to precipitation. The mean diameter of the humic acids aggregates was measured, detecting the formation of big molecular structures at low pH. This process is analysed and compared economically with other processes proposed for landfill leachate treatment, resulting in a promising technique for the management of this residue.

Improving soil properties and Sesbania growth through combined organic amendment strategies in a coastal saline-alkali soil.

Improving the quality of degraded coastal saline-alkali soil and promoting plant growth are key challenges in the restoration of ecological functions in coastal regions. Organic ameliorants such as effective microbial (EM) agent, biochar, and organic compost have been proposed as sustainable solutions, but limited research has explored the combined effects of these amendments. This study investigates five organic improvement strategies: individual applications of EM, corn straw biochar (CSB), and sewage sludge-reed straw compost (COM), along with combined treatments of CSB+EM and COM+EM, on Sesbania growth in a pot experiment. The results demonstrated that, compared to the separate applications, the combined strategies (CSB+EM and COM+EM) exhibited a greater improvement in Sesbania growth; for instance, the plant dry weight was 4.61-12.1 times that of the control. The improved plant growth was linked to enhanced nutrient uptake and changes in soil properties. The combined strategies, particularly COM+EM, resulted in greater decreases in soil pH (decreased by 2.79%-3.49% compared to the control) and better improvements in soil nutrient content, quantity and quality of dissolved organic matter, microbial community diversity, and the abundance of plant growth-promoting rhizobacteria (PGPR), e.g., Bacillus. Spearman correlation and structural equation modeling confirmed that these soil improvements directly contributed to enhanced plant nutrient uptake. Overall, these findings suggest that combined strategies of COM+EM and CSB+EM, particularly the former, are highly effective for the remediation of coastal saline-alkali soils, offering a promising approach for improving soil fertility and plant productivity in degraded coastal ecosystems.

EFEITO DAS DOSES DE DEJETO LÍQUIDO DE SUÍNOS NOS ATRIBUTOS FÍSICOS, QUÍMICOS E ELETROQUÍMICOS EM UM LATOSSOLO DO CERRADO

EFFECT OF LIQUID SWINE WASTEWATER DOSES ON PHYSICAL, CHEMICAL AND ELECTROCHEMICAL ATTRIBUTES IN A CERRADO OXISOL. The addition of organic residues enhances soil and plant organic matter and nutrient content. To gauge the impact of varying liquid swine waste (LSW) levels on soil, we studied changes in a clayey Oxisol’s physical, chemical, and electrochemical traits from the Cerrado. LSW doses (0, 50, 150, 450, 600 m3 ha-1) were applied to the 0-0.20 m layer in a randomized design with three replicates. Post a 30-day incubation at 60% field capacity, the soil underwent mineralogical, physical (clay dispersed in water - CDW), chemical (sodium adsorption ratio - SAR, cation exchange capacity - CEC, base saturation - V%), and electrochemical (pH in H2O and KCl, ∆pH, point of zero charge - PZC, point of zero salt effect - PZSE, surface electric potential - ψo, and electrical conductivity - EC) analyses. The levels of exchangeable Ca, K, Mg, Na, and available P increased with increasing LSW doses. Increasing LSW doses in the soil led to an increase in EC, but soil salinization was not observed at the highest dose. With the application of LSW doses, there was a decrease in pH, ∆pH, PZSE, and an increase in CEC, PZC and ψo. Despite the increase in ψo, low clay dispersibility was observed.

Physicochemical and aromatic properties of iron-enriched tomato paste during storage

In this study, tomato paste was fortified with iron compounds at 25, 50, and 75 ppm concentrations. The effect of adding these micronutrient iron concentrations on the paste’s physical, mechanical, aromatic, and chemical properties was evaluated every 15 days over a 60-day, storage period. The results indicated a gradual decrease in pH, total soluble solids (TSS), and taste index, alongside an increase in total acidity (TA) for all treatments throughout the storage period. The highest lycopene content observed in the Fe-25 % fortified samples at 43.05 mg/kg and the lowest in the control samples at 21.57 mg/kg. Positive values for a* and b* at the beginning and throughout the storage period confirmed the dominance of red and yellow hues in the tomato paste. Viscosity gradually decreased over time. During storage, growth and changes in mold spores and acid-resistant thermophilic bacteria were limited until the 30th day, and total microorganism counts were restricted until the 45th day. The overall accuracy of the support vector machines (C-SVM) and linear discriminant analysis (LDA) method in distinguishing samples into four groups (control, fortified with 25, 50, and 75 ppm iron) were 38 % and 62 % Overall, it can be concluded that increasing the iron micronutrient enhances the nutritional value and positively affects the physical, chemical, and microbial properties and the retention of aromatic compounds in tomato paste.

Nutritional and antioxidative characterization, antimicrobial and sensorial stability of flaxseed powder supplemented mutton patties.

Oxidative stress and microbial growth deteriorate food quality and cause safety risks. Therefore, the present study was investigated to explore the nutritional, sensorial, anti-oxidative and anti-microbial attributes of flaxseed powder (FP) supplemented at 2-8% (i.e., T1-T4) level in mutton patties. Among extracts, the aqueous flaxseed extracts exhibited the highest total phenolic contents (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) activities i.e., 275mg GAE/g, 75% and 57mg/g, respectively. The results exhibited significant increase (p<0.05) in protein, and ash contents from 10.7 to 20.6 and 1.3-2.4 (g/100g) on addition of FP at 2-8% in mutton patties, respectively. Likewise, the mutton patties exhibited significant (p<0.05) decrease in pH and thiobarbituric acid reactive substances (TBARS) of T1-T4 from 7.1 to 3.4 and 317-46 than control i.e., 6.64-4.12 and 453.75-563 at 0-16days. Among color of mutton patties, L ⁎ values decreased from 37 to 25, while, b ⁎ values increased from 10 to 13 on addition of 2-8% FP in mutton patties at 0-16days for T1-T4, respectively. A significant decrease (p<0.05) in total plate counts (TPC), Salmonella and E. coli of mutton patties was recorded in T0-T4 from 4.2 to 2.8, 0.8-0.3, and 2.1-0.3, respectively at 16th day of storage, respectively. Sensory experts rated the T1 (i.e., 2% FP supplemented mutton patties) owing to their best sensory scores and overall acceptability. Conclusively, owing to better potential of FP in improving the nutritional and microbial quality of mutton patties, the study further suggests its ability to act as a novel functional ingredient of choice in shelf-life extension of other food products.

Biochar-based Bacillus subtilis inoculants promote plant growth: regulating microbial community to improve soil properties.

Numerous studies support the synergistic use of biochar (BC) and plant growth-promoting rhizobacteria to enhance plant growth. Despite this, the complex and dynamic nature of soil environments necessitates further exploration of the interactions between soil microorganisms and soil properties under BC-based inoculants. This study investigated their combined effects using a BC-based inoculant, Bacillus subtilis SL-44 (BC@SL), to explore the relationship between microorganisms and soil properties. Additionally, differentiating the effects of exogenous auxiliaries BC, SL-44, and BC@SL, which can promote plant growth, enhance plant and soil enzyme activities, regulate microbial communities, and increase soil nutrient content. Compared to BC alone, SL-44 enhances plant superoxide dismutase, peroxidase, and catalase enzyme activities, while BC increases soil cellulase and urease activities. SL-44 elevates Bacillus content, whereas BC boosts overall microbial abundance. Although initial values of most soil properties remain stable under exogenous auxiliaries, by the fourth week, soil pH and organic matter decrease, while electrical conductivity, available phosphorus, and ammonium nitrogen increase significantly across treatments. BC@SL, integrating the advantages of both BC and SL-44, exhibits superior performance. Under BC@SL treatment, Bacillus content rises from 4.36% to 14.96%, and available phosphorus and ammonium nitrogen increase by 81.97% and 53.16%, respectively. Additionally, plant dry weight increases by 51.95%. These results highlight the effectiveness of BC@SL in microbial regulation, soil nutrient enhancement, and plant growth promotion. In summary, BC@SL proves to be a stable and efficient solid soil additive, supporting the advancement of green fertilizer practices.

Remediation of a diesel contaminated soil by means of anionic and non-ionic surfactants: Effect on soil phosphorus availability and Vicia Faba L. growth.

In the present study, the effectiveness of two surfactants (Polysorbate 80 - Tween 80 and Sodium Dodecyl Benzensulphonate - SDBS) was investigated for the remediation of a hydrocarbon-contaminated soil. Moreover, it was elucidated the impact of surfactants on soil phosphorus (P) availability and phytotoxic effect on the growth of Vicia Faba L. An experimental laboratory-scale apparatus (bench and pilot scale) was set up for the simulation of a soil flushing intervention. Different surfactant concentrations and flushing flow rates were investigated. Hydrocarbon extraction efficiency was evaluated after treatment and phytotoxicity tests were performed by means of germination index (GI). The treated soil with the pilot scale apparatus was then used for Vicia Faba (faba beans) cultivation in pots. The growth of Vicia Faba plants was monitored and, at the end of the growth period, the plants were uprooted and subjected to biometric and chemical analyses. Results highlighted that the use of surfactants significantly increased the efficiency of hydrocarbons extraction compared to flushing test with water (19.6%, 53.9%, and 65.6% for water, 0.1% by weight of Tween 80 and SDBS, respectively, at pilot scale). Referring to Vicia Faba L., the plants grown in the blank control and in the soil treated with Tween 80 reached the same average height thus suggesting that this surfactant does not inhibit plant growth. In contrast, the lowest plant growth occurred in the soils treated with SDBS; this suggests a negative impact on plant growth. Due to the reduced plant growth, total P uptake was the lowest in plants grown in SDBS-treated soils, although such soils experienced a 20% increase of soil available P. This increase could be ascribed to P supplied by the surfactant or high P availability as a consequence of soil pH decrease.

Role of pH in Modulating RNA-Protein Interactions in TRBP2-dsRBD2: An Interplay between Conformational Dynamics and Electrostatic Interactions.

Understanding RNA-protein interactions is crucial for uncovering the mechanisms of cellular processes and can provide insights into the basis of various diseases, paving the way for the development of targeted therapeutic interventions. Exposure to stress conditions, such as hypoxia, leads to a drop in intracellular pH, which, in turn, alters the ionization states of amino acid residues and RNA bases, affecting the charge distribution and electrostatic interactions between RNA and proteins. In addition, pH also perturbs the structure and dynamics of proteins via the disruption of H-bonds and ionic interactions. Thus, it is crucial to ascertain the role of pH in modulating such interactions. We have previously shown the role of conformational dynamics in the RNA-protein interaction in TAR RNA-binding protein (TRBP) double-stranded RNA-binding domains (dsRBD) 1 and 2 using solution-state NMR spectroscopy. The current study provides insights into the effect of pH on interactions between TRBP2-dsRBD2 and a dsRNA. Remarkably, it was observed that a unit decrease in pH leads to an increase in the flexibility of TRBP2-dsRBD2 in RNA-binding residues, as seen in NMR dynamics experiments, in addition to altering the charge distribution on the protein surface. This led us to propose a dynamics-driven model where the two effects of pH, electrostatic and conformational flexibility, counterbalance each other. Thus, it can be concluded that the overall binding affinity between the protein and RNA is governed by a delicate balance between its conformational dynamics and electrostatic interactions.

Nanodots of Transition Metal Sulfides, Carbonates, and Oxides Obtained Through Spontaneous Co-Precipitation with Silica.

The controlled formation and stabilization of nanoparticles is of fundamental relevance for materials science and key to many modern technologies. Common synthetic strategies to arrest growth at small sizes and prevent undesired particle agglomeration often rely on the use of organic additives and require non-aqueous media and/or high temperatures, all of which appear critical with respect to production costs, safety, and sustainability. In the present work, we demonstrate a simple one-pot process in water under ambient conditions that can produce particles of various transition metal carbonates and sulfides with sizes of only a few nanometers embedded in a silica shell, similar to particles derived from more elaborate synthesis routes, like the sol-gel process. To this end, solutions of soluble salts of metal cations (e.g., chlorides) and the respective anions (e.g., sodium carbonate or sulfide) are mixed in the presence of different amounts of sodium silicate at elevated pH levels. Upon mixing, metal carbonate/sulfide particles nucleate, and their subsequent growth causes a sensible decrease of pH in the vicinity. Dissolved silicate species respond to this local acidification by condensation reactions, which eventually lead to the formation of amorphous silica layers that encapsulate the metal carbonate/sulfide cores and, thus, effectively inhibit any further growth. The as-obtained carbonate nanodots can readily be converted into the corresponding metal oxides by secondary thermal treatment, during which their nanometric size is maintained. Although the described method clearly requires optimization towards actual applications, the results of this study highlight the potential of bottom-up self-assembly for the synthesis of functional nanoparticles at mild conditions.

Molecular Dynamics Simulation on the Conformational Change of a pH-Switchable Lipid.

pH-sensitive lipids are important components of lipid nanoparticles, which enable the targeted delivery and controlled release of drugs. Understanding the mechanism of pH-triggered drug release at the molecular level is important for the rational design of ionizable lipids. Based on a recently reported pH-switchable lipid, named SL2, molecular dynamics (MD) simulations were employed to explore the microscopic mechanism behind the membrane destabilization induced by the conformational change of pH-switchable lipids. The simulated results showed that, at neutral pH, the neutral SL2 lipids assembled with other components (helper lipids and cholesterol) to form a structurally ordered bilayer structure. At this moment, the two hydrocarbon chains of SL2 were closely aligned and inserted in an orderly manner inside of the membrane. With a decrease in pH, the protonation of the pyridinium ring caused a large degree of molecular structural change. The pyridinium ring preferred to form intramolecular H-bonds with the methoxy groups and intermolecular H-bonds with water, resulting in the flip of the pyridinium ring. Meanwhile, due to the structural flip, the two alkane chains showed a more open state, which perturbed the arrangement of molecules within the membrane. The perturbations caused local collapse of the membrane and the formation of water molecule channels, which contributed to the pH-induced drug release. Our results verified the experimentally proposed mechanism at the molecular level and provided more complementary information, which are expected to have deeper insights into the pH-triggered drug release.

THE EFFECT OF COLD BREW AND HOT BREW EXTRACTION METHODS AND DURATION OF FERMENTATION ON THE QUALITY OF ROBUSTA COFFEE WINE (Coffea canephora) TEMANGGUNG

This study examines the effect of fermentation duration and extraction methods (cold brew and hot brew) on the quality of robusta wine coffee. Wine coffee is a beverage resulting from the fermentation process of coffee extract which is providing a unique taste with a blend of coffee and alcohol flavors, along with a characteristic wine aroma. Through these two extraction methods, cold brew and hot brew offer different characteristics to the chemical parameters such as pH, reducing sugar content, alcohol content, caffeine content, and flavor. The research results indicate that cold brew yields a lighter flavor, while hot brew tends to have a stronger or more bitter taste. The duration of fermentation significantly affects the chemical parameters, with a decrease in pH and reducing sugar content as fermentation time increases. The alcohol content in cold brew reaches 19.93% on day 28, higher than hot brew which has 18.40% of alcohol. Organoleptic analysis results show that cold brew is preferred by the panelists, especially on the 28th day of fermentation.

PENGARUH PENAMBAHAN MADU GALO-GALO TERHADAP AKTIVITAS ANTIBAKTERI KOMBUCHA KULIT NANAS DAN AIR KELAPA

Kombucha is a fermented beverage known for its various health benefits, one of which is its antibacterial properties, making it a potential base for soap production. This study aims to evaluate the effect of adding Galo-Galo honey on the antibacterial activity of kombucha made from pineapple peel and coconut water waste. Fermentation was carried out for 15 days, and observations were made on pH value, total titratable acidity (TTA), and antibacterial activity against Escherichia coli using the disk diffusion method. The study was designed using a completely randomized design with three repetitions. The results showed that the higher the concentration of Galo-Galo honey added, the more significantly the kombucha pH decreased (p &lt; 0.05), with the lowest pH found in the 25% honey treatment (3.09 ± 0.02). The highest total titratable acidity was also found in the 25% honey treatment (1.33 ± 0.11), along with the decrease in pH, indicating an increase in organic acid content. The antibacterial activity test showed that kombucha with a higher honey concentration had a larger inhibition zone against E. coli, with the largest inhibition zone found in the 25% honey treatment (11 ± 1.26 mm). The addition of Galo-Galo honey was proven to enhance the chemical properties of kombucha and strengthen its antibacterial activity.

A study for the genotoxicity assessment of substances containing probiotic candidates in the in vitro TK6 cell micronucleus test: Influence of low pH conditions and antibiotic supplementation on the test results

BackgroundWhen assessing the genotoxicity of substances containing probiotic candidates, such as lactic acid-producing bacteria, using the in vitro micronucleus test (MNT), bacterial growth in the test medium may reduce the pH of the medium. The low medium pH is known to induce cytotoxicity and false-positive results. In the TK6 cell system, it is difficult to completely remove the bacteria from the medium by washing post-treatment, leading to bacterial growth during the recovery period in the short-term treatment. In the present study, the low pH range yielding false positives in the TK6 cell MNT was investigated using media supplemented with acetic, lactic, or formic acids, which are non-genotoxic bacterial metabolites. Additionally, to suppress the bacterial growth during the recovery period using antibiotics, i.e., penicillin/streptomycin (P/S), gentamicin sulfate (GM), and amphotericin B (AP), the maximum applicable concentrations of them that did not affect TK6 cell growth or micronucleus induction were determined. Then, we conducted an MNT using a substance containing live lactic acid-producing bacteria to verify the effectiveness of the antibiotics.ResultsAcetic, lactic, and formic acids induced micronuclei in TK6 cells (false positive) at an initial pH of ≤ 6.2 and ≤ 6.0 in 3 h treatment with and without S9 mix, respectively, and of ≤ 6.7 in the continuous treatment. Media supplemented with P/S, GM, and AP did not affect TK6 cell growth or micronucleated cell frequencies in the negative and positive controls ≤ 400 unit/mL-400 µg/mL, ≤ 250, and ≤ 20 µg/mL, respectively. In an MNT with fermented milk containing live lactic acid-producing bacteria, supplementation with P/S or GM to media for the recovery cultures suppressed the bacterial growth, decreasing pH, and cytotoxicity.ConclusionThis study revealed the low pH ranges yielding false positives in the TK6 cell MNT under short-term and continuous treatment conditions. These values will serve as references for interpreting the biological relevance of results. Under short-term treatment, optimal antibiotic supplementation in recovery cultures suppressed bacterial growth in the test substance and prevented the decrease in pH that could yield false positives. This approach might be useful for evaluating the genotoxicity of test substances containing probiotic candidates using the MNT.

Effect of Different Formulations and Storage on the Physicochemical, Microbiological, and Organoleptic Characteristics of Dovyalis caffra Fruit Yogurt.

This study investigated the effect of incorporating up to 15% (w/w) Dovyalis caffra fruit pulp into cow milk yogurt. Monitoring the physico-chemical, microbiological, and organoleptic properties of these formulations was performed weekly during refrigerated (4 °C) storage for 21 days. Compared to the control, formulations with added pulp recorded enhanced contents of ascorbic acid, total polyphenols, fiber, total titratable acidity (TTA), and yellowness, which is in line with increasing fruit pulp. This, however, corresponded to significantly lower contents in fat, protein, viscosity, pH, and overall sensory acceptability. Pulp incorporation had no significant effect on moisture, ash, and water-holding capacity (WHC) of formulations. Storage for up to 21 days indicated a significant increase in TTA and a corresponding decrease in pH but no significant change in WHC and viscosity of formulations. There was no detection of coliforms, yeasts, and molds in all samples throughout the storage period. This study demonstrates that Dovyalis caffra fruit has significant potential in the formulation of nutritious, desirable, and shelf-stable fruit-based yogurts. Further product optimization is, however, recommended to maximize the organoleptic quality of the formulations.

Effect of Cold PlasmaTreatment on Physicochemical and Microbiological Properties of Clotted Cream

The aim of this study was to determine the effect of cold plasma treatment, which was applied by using two different gases (O2 and Ar) and their mixtures onto sample surfaces for different intervals, on the physicochemical and microbial parameters of clotted cream during storage for up to 10 days. Cold plasma treatment caused a decrease in pH, aw, L*, and b* values of clotted cream samples and an increase in their a* and TBA values. The pH values of samples ranged from 4.68 to 6.67, and the range for aw values was between 0.903 and 0.803. For TBA, the highest change was observed in the K2 sample with 0.479 mg malondialdehyde/kg. The color L* values of all samples were between 99.79 and 93.82, a* values between 1.82 and 1.22, and b* values between 6.22 and 4.74. Among the treatments, the treatment of O2-Ar gas mixture (50-50%) resulted in the highest decrease in the total counts of aerobic mesophilic bacteria (TMAB), total aerobic psychrophilic bacteria, proteolytic bacteria, yeast-molds, coliform group bacteria, and Staphylococcus aureus. Compared to the control sample, at the end of 10 days of storage, a decrease of 2.41 for TMAB, 3.64 for total yeast-mold, 4.23 for coliform group bacteria, and 4.72 log cfu/g for S. aureus was achieved. Results indicated that the cold plasma treatment did not cause significant changes in the physicochemical values of clotted cream samples but reduced their microbial load.