Decrease Of pH Value Research Articles

Effect of Plant Extracts Addition on the Physico-Chemical and Sensory Properties of Biscuits

Biscuits are one of the most consumed bakery products that contain a high content of fat, sugar, and different additives that may cause various health problems. This has led to an increased focus on enriching bakery products with plant extracts to improve their nutritional and sensory properties. The objective of the current work was to investigate the effect of replacing wheat flour with plant extracts such as blueberry and cranberry (at concentrations of 3%, 6%, and 9%) and compare with control biscuits regarding the physico-chemical and color parameters. In addition, sensory analysis was conducted to determine the consumer acceptability of the enriched biscuits. The enrichment of biscuits with blueberry powder significantly increased the moisture content and decreased pH values (p < 0.05). Similarly, cranberry-enriched biscuits had a significantly higher moisture content, water activity, and decreased pH values compared to control samples (p < 0.05). On the other hand, enrichment of biscuits with either blueberry or cranberry powder significantly decreased lightness (L*), yellowness (b*), chroma value (C*), and h-value (h) but increased the redness values (a* value) of samples (p < 0.05). Our results showed that with increasing concentrations of plant extract addition in biscuits, the sensory attributes such as odor and taste were significantly improved. The results of the study suggest that the addition of plant extracts to biscuits improved their physico-chemical and sensory properties.

Aggregation kinetics of green tea nanoparticles: Effects of pH, metal ions, and temperature.

Colloidal nanoparticles in tea infusion are the link connecting micromolecular mechanism and macro-aggregation process of tea cream formation. In order to elucidate, the kinetics mechanism of green tea nanoparticles (gTNPs) aggregation, zeta-potentials, total average aggregation (TAA) rates, and critical coagulation concentration (CCC) in the presence of various pH and metal ions were investigated. Additionally, the effect of temperature on gTNPs aggregation was further explored. The results revealed that the TAA rate of gTNPs increased with decreasing pH values, the CCC of gTNPs increased in the order Mg2+ ≈Ca2+ <Na+ ≈K+ . The reason was that different positive ions changed the surface electric field strength of gTNPs to a different extent. Furthermore, it was indicated that low temperature could promote gTNPs aggregation in indirect way. Low temperature promoted the binding of epigallocatechin gallate (EGCG) and caffeine, and the combination between gTNPs and EGCG-caffeine complexes weakened the stability of gTNPs resulting from reduction in electrostatic repulsion. PRACTICAL APPLICATION: Tea is a popular beverage all over the world. This research revealed the mechanism of green tea nanoparticles aggregation and laid a theoretical foundation for the regulation of tea cream formation in tea beverage.

Decreasing pH, COD and TSS of Domestic Liquid Waste Using Photocatalysis TiO2 (Titanium Dioxide)

Domestic waste comes from households that must be treated. Based on the Minister of Environment and Forestry Regulation Number P.68/Minister Environment and Forestry-Secretary General/2016 concerning Domestic Wastewater Quality Standards, the government has set a maximum limit for waste water that can be disposed of to the environment or receiving water bodies. includes pH, TSS and COD parameters. This is useful for overcoming the problem of environmental pollution caused by wastewater. Waste water that is not managed properly will have an impact on human health. environmental pollution is harmful to humans. Domestic sewage treatment using a titanium dioxide photocatalyst shows the results of testing the pH value on domestic waste as shown below, showing that overall the concentration of parameters has increased the pH value decrease 90% from acidic to normal with the best pH value with a value of 6.57 at a contact time of 210 minutes of mass catalyst 2.5 grams. Parameter concentration decreased TSS value from initial value of 157 mg/L to normal with the best TSS value of 94 mg/L at contact time of 210 minutes with catalyst mass of 2.5 grams. COD value at contact time of 210 minutes with a mass of 2.5 grams of catalyst with a value of 2861 mg/L. COD value affects the time and mass of the catalyst (1). a decrease of 40.1% where the TSS value meets the quality standard, and the COD value has decreased by 31%. Addition of further processing to get a better COD.

Study on the color-changing mechanism and law of visual formaldehyde sensing system based on hyperbranched polyamines

This study focuses on addressing the limitations associated with most chemical derivatization methods commonly used for formaldehyde detection. These methods often suffer from prolonged derivative times (≥30 min) and complex procedures, which hinder their ability to meet the requirements of real-time and accurate sensing. In this research, a novel formaldehyde indicator system based on hyperbranched polyamine molecule was developed, and its mechanism and principles of color change were investigated. The findings revealed that hyperbranched polyamine molecule effectively reacts with formaldehyde, leading to a reduction in electron cloud density in the amine group N and subsequently causing a decrease in pH value. This reaction enables the visualization of formaldehyde detection through changes in the indicator spectrum. Moreover, the spectral variation pattern exhibits a strong linear correlation with the formaldehyde concentration when the PAMAM concentration is optimized. The detection limit of this method was determined to be 1.8 ppm. Notably, the reaction between PAMAM and formaldehyde is almost instantaneous, the color change is insensitive to temperature, and the method demonstrates high selectivity. Overall, this research contributes to the advancement of real-time formaldehyde monitoring technology and provides insights for future developments in this field.

Simulated gastrointestinal digestion and gut microbiota fermentation of polysaccharides from Agaricus bisporus.

Agaricus bisporus, an edible mushroom, is grown and consumed worldwide for its delicious taste and multiple health benefits. A. bisporus polysaccharides (ABP) are the main bioactive ingredient of the mushroom that confers health benefits. In this study, we prepared and characterized ABP, and the digestion, fermentation prosperities, and the effect of ABP on gut microbiota were detected via in vitro simulated digestion and gut microbiota fermentation. The results showed that during the simulated digestion process, the molecular weight of ABP was unchanged, and no free monosaccharide was produced, indicating that ABP could not be digested completely. However, after the fermentation, gut microbiota degraded and utilized ABP, which produced short-chain fatty acids and caused a decrease in pH value. Meanwhile, ABP modulated the gut microbiota composition by increasing the abundance of beneficial bacteria. The results suggested that ABP is a promising food component with prebiotic potential.

Production of Lactic Acid by lactobacilli using Legume Flours

Due to their high nutritional value, richness in carbohydrates and good source of protein, legumes are considered essential for human diet. Legumes flours were used as fermentable material for lactic acid production. Hence, previously isolated lactobacilli strains were used in this study. The strains showed strong microbial growth and their survival in glucose-containing MRS medium and were described using a modified Gompertz equation. Lactobacilli exhibited the shortest latency phase in MRS-glucose medium. While the highest lactic acid produced was 15.40g/l by Lpb. pentosus U1 isolate after 48hours. Furthermore, these strains were evaluated in flours samples for acidification capacity. The results showed a decrease in pH values after 12hours of fermentation, indicating the fastest acidification with maximum lactic acid generation of 31.66, 25.33, 31.00 and 31.66g/l for black gram flour by Lpb. plantarum M1, Lpb. pentosus U1, Lpb. plantarum VIP1 and Lev. brevis TIP1 isolates. Black gram flour was considered the best among the used substrates for enhancing lactic acid production. Overall, this study can be termed as a preliminary step for fermentation using the desired organism in preparing legume-based food at the industrial level and benefiting consumers.

Successional Changes in Vegetation Communities near Mine Pits

This study investigates demutational changes in plant communities of phosphorite mines between 2005 and 2021. A total of 23 plant species were initially found in the surveyed areas in 2005, while 68 species were identified in spring 2021. The plant communities were categorized into five different groups, with the older communities (No. I and II) exhibiting richer vegetation and greater diversity. Community No. III comprised various cereals, legumes, orchid plants, and mosses. Dominant species in community No. I included Betula pubescens, Carpinus betulus, Quercus robur, and Picea obovata, while community No. II featured Juniperus communis, Larix sibirica, Pinus sylvestris, and Abies sibirica. Erosion was observed in community No. V on slopes of different ages. The study also found changes in physicochemical indices, such as increased organic matter concentration and decreased pH value (4.9). The basal respiration rate of the pit soil was low (around 0.4 mg CO2/m2/h), and carbonate content ranged from 0.06 to 0.9%. This study presents novel data on the dynamics of species composition, plant community structure, and physicochemical soil parameters in human-altered habitats, thereby contributing to the expansion of our knowledge of vegetation recovery and evolution in such environments.

Scholastic modeling of pH and redox potential changes in olive tree leaf alcohol and acids containing incubation media designed for the steady growth of Acetobacter aceti and Saccharomyces cerevisiae

Modeling of pH and redox potential changes was investigated instructionally in incubation media designed for a stable growth of Acetobacter aceti and Saccharomyces cerevisiae. Olive tree leaf, phosphoric acid, vinegar, acetic acid and ethyl alcohol were used in incubation for extraction and symbiotic purposes. Structure imaging of olive tree leaf powder was performed using the Field Emission Gun – Scanning Electron Microscope (FEG-SEM). The incubation experiments were carried out at initially lowest pH and high temperatures of 30oC and 35oC for eight days in liquid state fermentation process. A steady A. aceti and S. cerevisiae growth was observed during the incubation. Increase in pH value displayed increase in redox potential in water+ phosphoric acid, vinegar+A. aceti+phosphoric acid, S. cerevisiae+A. aceti+acetic acid+phosphoric acid and S. cerevisiae+A. aceti+phosphoric acid solution processes at 30oC, and acetic acid+phosphoric acid and vinegar+phosphoric acid solution processes at 35oC. Decrease in pH value displayed decrease in redox potential in A. aceti+alcohol+phosphoric acid, vinegar+phosphoric acid, S. cerevisiae+A. aceti+acetic acid+phosphoric acid and S. cerevisiae+A. aceti+phosphoric acid solution processes at 30oC, and vinegar+A. aceti+phosphoric acid, S. cerevisiae+A. aceti+acetic acid+phosphoric acid and S. cerevisiae+A. aceti+phosphoric acid solution processes at 35 oC.

Effects and control mechanisms of ammonia, particulate matters and aerosol bacterial compositions in poultry houses by spray technology

Spray technology is an efficacious method to improve the indoor environments of poultry houses. In this study, two kind intensive enclosed poultry houses are sprayed with different spray additives in order to explore the effects and control mechanisms of spray processes on ammonia, particulate matters and aerosol bacterial compositions and investigate the fecal contributions to aerosol bacteria. The results show that the ammonia elimination rates through spray treatment by tap water (TP treatment), by EM microbial agent (EM treatment) or by glutaraldehyde-decamethonium bromide solution (HX treatment) are 67.0%, 85.4% and 96.9% in brood hen house and 60.7%, 76.0% and 94.8% in laying houses. The reductions of ammonia are mainly due to the decreased pH values caused by the increased Lactobacillus in chicken manure rather than the effects of aerosols after spraying. Spray processes reduce the contents of particulate matters while increase the proportions of PM10 and PM2.5 in TSP. The aerosol bacterial compositions after spraying alter mildly. Humidity is the main physicochemical factor leading to the variations of core bacteria in aerosols. The fecal transmission is the major source of aerosol bacteria in poultry houses and the spray processes merely present a relatively small impact on the fecal contribution to aerosol bacteria. The findings are conductive to optimize the breeding environment, enhance the ability of disease prevention and finally achieve the green and efficient cultivation.

3D/4d printing of β-cyclodextrin-based high internal phase emulsions

The β-cyclodextrin (β-CD) based high internal phase emulsions (HIPEs) were prepared as building blocks for engineering high-quality 3D shapes and achieving 4D color transformation. The increase of β-CD concentration, the decrease of pH value, and the addition of NaCl contributed to the adsorption of β-CD molecules at the oil-water interface and the improvement of the microstructure, rheological properties and printing quality of the Pickering HIPEs. Moreover, the 4D printing of Pickering HIPEs was achieved by introducing pH-sensitive curcumin and heat-labile NaHCO3. With the increase in heating temperature, heating time and NaHCO3 concentration, the decomposition of HCO3− to CO32− led to an elevation in pH, which induced the conformational change in curcumin, accompanied by a decrease in L* and b × values and an increase in a × value of the samples. These findings dramatically improve the pleasure of diet and take full advantage of the custom design benefits of 3D printing technology.

Studies on postharvest loss assessment of Tomato fruits using Aloe Vera gel as mitigating agent

This work evaluates effect of aloe gel coatings on post-harvest quality management of red ripe tomato fruits. Red ripe tomato fruits were purchased from Mandate market, Ilorin, Kwara State. It was sorted and washed with potable water. The sample was divided into four (4) lots for dip treatment in already prepared different aloe vera solutions and labelled: A0 (control), A1 (1.5% aloe vera), A2 (50% aloe vera) and A3 (100% aloe Vera). The pre-treated lots were stored on a laboratory shelf at ambient for 15 days. Physicochemical and nutritional properties were evaluated using standard procedures. Moisture (97.58%) and ash contents (0.68%) of lot A3 (100% aloe gel) were significantly higher (p&lt;0.05) than the other lots. Results showed that lot A1 had the lowest weight loss of 13.1%, while A3 recorded the highest (37.2%). Lot A1 had significantly (p&lt;0.05) higher sensory attributes than the other lots. At day 15, TTA was between 0.13 and 0.35 %, with lot A1 recording significantly (p&lt;0.05) higher value of 0.35 %. TSS content of the tomato fruits decreased with increase in storage with exception to lot A2 which had the highest value (5.30 oBrix). There was a decrease in pH value of both the untreated and treated lots. The results also showed that the vitamin C content of the stored tomato fruits increased significantly (p&lt;0.05) in all the lots as storage days progressed. The result from the study showed that Lot A1 retarded water loss and delayed fruit softening thereby making them acceptable to consumer.

P-coumaric acid prevents Colletotrichum gloeosporioides by inhibiting membrane targeting and organic acid metabolism

The objective of this study was to investigate the antifungal activity of p-coumaric acid (p-CA) against Colletotrichum gloeosporioides (C. gloeosporioides), and elucidate the underlying antifungal mechanism from aspects of organic acid secretion and membrane targeting level. p-CA treatment inhibited increase of lesion diameter on fruit and mycelial growth, spore germination and germ tube elongation caused by C. gloeosporioides, the effect was positively correlated with the concentration. Importantly, C. gloeosporioides secretes organic acids during its growth, including malic acid, citric acid and lactic acid. However, the addition of p-CA inhibited the increase of total acid content and the decrease of pH value, as well as the secretion of organic acids. In summary, p-CA can inhibit the growth of C. gloeosporioides in fruit, and plays an inhibitory role by inducing cell membrane damage and inhibiting organic acid secretion.

Schiff base synergized with protonation of PEI to achieve smart antibacteria of nanocellulose packaging films

Microbial growth and reproduction can cause food spoilage. Developing the controlled release packaging films for food is an ideal solution. In this study, polyethyleneimine (PEI) was grafted to cellulose nanofibers (CNF) films by Schiff base, and when the CNF/PEI films were stimulated by pH, PEI released from the CNF/PEI films due to Schiff base hydrolysis, improving the antibacterial efficiency of PEI. Stimulated by acid with pH of 4, the PEI cumulative release rate of the CNF/PEI800 and the CNF/PEI2000 films reached to 92.90 % and 87.28 %, respectively. At the same time, the amino groups of PEI protonated by obtaining H+, the charge density increased, and PEI molecular chains extended, enhancing the antibacterial activity of films. The Zeta potential value on the surface of the CNF/PEI film increased with the decrease of pH value. Schiff base synergized with protonation of PEI to achieve smart antibacteria of CNF packaging films. The antibacterial rates of the film against L. monocytogenes and E. coli were 94.7 % and 90.6 % at pH 4, but 29.5 % and 23.6 % at pH 8, respectively. The developed films also had good barrier properties of oxygen, visible light and mechanical properties, and had an attractive application prospect in food preservation to control release of antibacterial agent.

Effects of Phenyllactic Acid on Fermentation Parameters, Nitrogen Fractions and Bacterial Community of High-Moisture Stylo Silage

To investigate the effect of phenyllactic acid (PLA) on the dynamic changes of high-moisture stylo silage, fresh stylo was ensiled with addition of PLA at the levels of 0, 1% and 2% using lab-level silage bags, where samples were collected on days 3, 7, 14 and 30 of ensiling fermentation to analyze fermentation parameters, nitrogen distribution and bacterial community. The results showed that PLA addition at ensiling led to the increase (p &lt; 0.01) in dry matter content, lactic acid concentration and Flieg’s score of stylo silage as well as the decrease (p &lt; 0.01) in dry matter loss, pH value and coliform bacteria population, with butyric acid only detected in the control group. It also resulted in the increase (p &lt; 0.01) in true protein content and its proportion as well as the decrease (p &lt; 0.01) in ammonia-N content and its proportion, almost with linearly dose effect. Sequencing analysis revealed that PLA addition led to the increase (p &lt; 0.05) in Sobs, Shannon, Chao and Ace of bacterial community in the stylo silage, where the relative abundance of Enterobacter, Clostridium, and Kosakonia was decreased, and that of Lactobacillus, Enterococcus and Pantoea was increased. Furthermore, Kosakonia, Terriglobus, Sphingomonas and Sphingopyxis had an important role in the bacterial interaction network. It is suggested that PLA application at the level of 1–2% could improve silage quality of stylo silage via modifying bacterial community.

Influence of H2O/MgCl2 molar ratio on strength properties of the magnesium oxychloride cement solidified soft clay and its associated mechanisms

The solidifying soft soils with eco-friendly magnesium oxychloride cement (MOC) have gained much attention due to increasing environmental protection concerns. In this paper, a parametric study has been conducted to investigate the influence of H2O/MgCl2 molar ratio on the mechanical properties of MOC-solidified soft clay at different MgO/MgCl2 molar ratios and curing times by performing unconfined compressive strength (UCS) tests. The microstructure and pH were studied to the inherent mechanisms by scanning electron microscopy (SEM), X-ray diffraction (XRD), and acid-base tests. The results indicate that the influence of the H2O/MgCl2 molar ratio on the mechanical properties of solidified soft clay is dependent on MgO/MgCl2 molar ratio. The optimal H2O/MgCl2 molar ratio was found as 15–20 when MgO/MgCl2 molar ratio was 3:1 – 5:1, while it was 29 – 41 when MgO/MgCl2 molar ratios were 6:1 and 7:1. The main hydration products of MOC-solidified soft clay with MgO/MgCl2 molar ratio of 3:1 – 4:1 were 5 Mg(OH)2·MgCl2·8H2O (phase 5) and 3 Mg(OH)2·MgCl2·8H2O (phase 3), whereas phase 5 and Mg(OH)2 were mainly produced when MgO/MgCl2 molar ratio was 5:1–7:1. The UCS increases and then exhibits a decreasing trend with the curing time due to the gradual transformation of phase 5 into phase 3 and Mg(OH)2. The influence of curing time is dependent on H2O/MgCl2 molar ratio. The pH value first increases and then decreases with the H2O/MgCl2 and MgO/MgCl2 molar ratios, while it decreases with the curing time. The decreasing pH value results in the instability of the hydration products and reduced UCS of MOC-solidified soft clay.

In vitro and in situ caries-preventive effect of a new combined fluoride and calcium experimental nanocomposite solution.

To assess the in vitro and in situ effect of experimental combined fluoride and calcium nanocomposite solutions on dental caries prevention. Nanocompound mesoporous silica (MS) with calcium (Ca) and sodium fluoride (NaF) - (MSCaNaF); MS with NaF (MSNaF), NaF solution (positive control), and deionized water (negative control - CG) were studied. The specimens (n=130) were submitted in vitro to a multispecies biofilm in the presence of 2% sucrose. After 24 h and 48 h, the culture medium pH, the percent of surface mineral loss (%SML), and lesion depth (ΔZ) were analyzed. In the in situ study, 10 volunteers participated in four phases of 7-days each. The products were applied on the specimens (n=240) before 20% sucrose solution drips. The polysaccharides (SEPS and IEPS), %SML and roughness (Sa) were evaluated. There was an in vitro decrease in pH values in 24h and 48h, compared to baseline. The MSCaNaF and MSNaF groups obtained lower values of %SML and ΔZ (p < 0.05) than CG and NaF after 24h and were similar to NaF after 48h (p<0.05). In situ results showed similar SEPS and IEPS among all groups after 48h. An after 7-days, the nanocomposites had similar values (p>0.05), while NaF was similar to CG (p>0.05). After 48h, the MSCaNaF and MSNaF reduced the %SML (p<0.05). After 7-days, both experimental nanocomposites were similar to NaF (p>0.05). Regarding Sa, MSCaNaF was better than NaF for both periods (p<0.05). The nanocomposites controlled the in vitro and in situ enamel demineralization, mainly in the initial periods.

Enhancement of the quality attributes and health benefits synbiotic yoghurt from cow's milk

The present work delighted on extraction of galactomannan polysaccharide from guar gum beans and microbial galactomannan source. Effect of replacing non-fat dry milk that used to fortify cow's milk in yoghurt industry with the two extracted galactomannans and commercial galactomannan as food additives was studied. Control yoghurt treatment was made from 3.0% fat cow's milk that was fortified with 1.5% non-fat dry milk. Another 6 yoghurt treatmentwas fortified with 0.15, 0.25% of commercial, guar and microbial galactomannan respectively. All treatments were cultured with the probiotic starter (1.0% Streptococcus thermophilus + 1.0% Lactobacillus delbrueckii subsp. Bulgaricus + 1.0% Bifidobacteriumbifidum). The obtained results indicated that yoghurt supplementation with the three types of galactomannans increased the acidity, curd tension, total solids content, decreased pH values and syneresis of yoghurt treatments. Control yoghurt and commercial galactomannan yoghurt were not significantly different from the corresponding batches those made with either guar galactomannan and microbial galactomannan in fat, protein and ash content. Yoghurt treatments which supplemented with the three types of galactomannans have higher bifidobacteria counts and organoleptic scores than the control treatment yoghurt.

Experimental Study on Time - Varying Law of Resistivity of Concrete Sulphuric Acid Corrosion

The change of concrete resistivity reflects the change of concrete porosity. The variation law of concrete resistivity within the age range of concrete is studied, and the effects of water binder ratio and fly ash content on concrete resistivity are studied. The change law of resistivity of concrete sulfuric acid corrosion was studied. The results show that the resistivity of concrete increases gradually with the increase of age. With the increase of water binder ratio and fly ash content, the resistivity increases with age. With the increase of sulfuric acid corrosion time, the concrete resistivity decreases gradually. With the decrease of sulfuric acid pH value, fly ash content and water binder ratio, the reduction range of concrete resistivity increases.

Graphene oxide reinforced chitosan/polyvinyl alcohol antibacterial coatings on stainless steel surfaces exhibit superior bioactivity without human cell cytotoxicity

The study proposes an alternative therapeutics to diminish bacterial attachment in biomedical implants by modifying their surface with passive coatings. A uniform, thin-film of chitosan/polyvinyl alcohol/graphene oxide (CS/PVA/GO) was coated on 316 L stainless steel (SS) surface through spread casting followed by solvent evaporation. The abundant anchoring sites available at macromolecular interfaces of chitosan/PVA matrix facilitated a smooth, dense loading of GO. The effect of GO content on physicochemical features, antibacterial potential, and biocompatibility of coatings was thoroughly studied. The hybrid films displayed good adhesion behavior, and UV-protection ability with desired mechanical and thermal stability when coated on SS surface. Coatings manifested a 1.5–1.7 fold rise in antibacterial efficacy against Staphylococcus epidermidis and Staphylococcus aureus and exhibited a permanent biocidal response after 6 h of contact-active behaviour. We investigated a 3-fold generation of reactive oxygen species as the predominant antibacterial mechanism, which diminishes bacterial integrity by inducing protein leakage (8.5–9 fold higher) and suppressing respiratory chain activity as two secondary mechanisms. All coatings with varying GO content appeared non-haemolytic (<2%) with ultra-low cytotoxicity (<29.08%) against human hepatocellular carcinoma (HepG2) and peripheral blood mononuclear cells. The degradation rate of coatings in simulated body fluid exhibited a higher stability, indicated by a lower weight loss (69–78%) and a decrease in pH values as the GO content in coatings increased from 0.05 to 0.15 wt%. Such anti-infective coating is a step forward in inhibiting bacterial colonization on SS surfaces to extend its lifespan.

Experimental Study on Mechanical Properties and Deterioration Mechanism of Red Sandstone from the Panjiatuo Landslide under Action of Acidic Drying−Wetting Cycles

Due to frequent water level fluctuations and complex hydrochemical environments, rock slopes in reservoir areas progressively deteriorate and become unstable. This study investigated the coupling effect of drying−wetting cycles and acidic solutions on the physical and mechanical properties, strain field evolution, failure mode, and micro-mechanism of red sandstone using a series of laboratory experiments (wave velocity tests, uniaxial compression tests, the digital image correlation method, scanning electron microscopy, and X-ray diffraction). The results showed that with increasing drying−wetting cycles, the mass, P-wave velocity, elastic modulus, and uniaxial compressive strength decreased monotonically, while the water absorption and apparent strain in the strain localization band increased. Moreover, the failure mode transitioned gradually from tensile failure to shear failure or tensile-shear composite failure. The decrease in the solution pH values aggravated the changes in the physical and mechanical parameters and contributed to an increase in the secondary cracks and the occurrence of shear behavior. In addition, the coupling effect of drying−wetting cycles and acidic solutions accelerated the worsening of the microstructure and the dissolution of minerals, resulting in a loose structure with well-developed pores and fissures. These changes provide a favorable explanation for the mechanical property deterioration of red sandstone subjected to acidic drying−wetting cycles.