Combination Of Citric Acid Research Articles

Development of an enhanced formulation to minimize pharmacokinetic variabilities of a weakly basic drug compound

Formulating poorly water soluble, weakly basic drugs with consistent exposure is often a challenge due to pH-dependent solubility. When the oral formulation is exposed to different pH ranges in the gastrointestinal (GI) tract, drug precipitation, or incomplete dissolution may occur resulting in decreased drug absorption and higher intra- and inter-patient pharmacokinetic (PK) variabilities. In the present study, a series of enhanced formulations containing organic acids and/or surfactants were developed and compared with conventional formulations with respect to their in vitro dissolution performance. The formulation containing 5% citric acid and 1% sodium lauryl sulfate (SLS) showed much less variations in dissolution performance at different pH conditions than a conventional formulation. The combination of citric acid and SLS demonstrated a synergistic effect as compared to use of citric acid alone or in combination with PEG4000 as a precipitation inhibitor. When compared with a conventional formulation and a spray-dried amorphous solid dispersion (ASD) formulation in a dog PK study, the enhanced formulation demonstrated the least AUC and C max variability between the two gastric pH-controlled groups. In conclusion, an enhanced formulation using a combination of organic acid and surfactant is recommended for weakly basic drug compounds to minimize drug PK variabilities in clinical studies.

Combustion synthesis and characterization of Li1.2Mn0.52Ni0.20Co0.08O2 cathodes for Li-Ion battery: Effect of fuel mixture and annealing temperature

The effect of fuel mixture and annealing temperature on the structural properties and electrochemical performance of Li1.20Mn0.52Ni0.20Co0.08O2 powders prepared by the combustion synthesis were studied. Different combinations of citric acid fuel and ammonium acetate along with post-temperature treatments could be used to control the product characteristics. Simultaneous thermal analyses and thermodynamic modelling were used to describe the combustion processes. The analysis of the XRD data and other reports showed that the synthesis method and chemical compositions of lithium-rich layered oxides (LLO) could influence their description either as a solid solution or a ‘composite’ structure. The annealing temperature greatly influenced the lattice parameters, unit cell volumes, crystallite sizes, and cationic disorder of the samples whilst the use of fuel mixture had little effect. Furthermore, the electrochemical performances of the cathode materials were studied and the relationship with the structural properties of the powder samples were analysed. The Li1.20Mn0.52Ni0.20Co0.08O2 powders synthesized with only citric acid fuel (100-T) displayed the best electrochemical performance compared with those produced using the fuel mixtures. The enhanced electrochemical performance of the 100-T cathodes was shown to be an integrative property of the highest values reported for their structural properties. The results show that citric acid assisted combustion and annealing temperature (mostly with pre-annealing) could be used to optimize the electrochemical performance of LLO cathode materials.

Effect of chemical modification and heat treatment on biological durability and dimensional stability of Pinus roxburghii Sarg.

Background: Depleting supplies of wood species with inherent natural durability has resulted in the focus being shifted to non-durable plantation grown and imported timber. Despite its abundant availability and better treatability, the use of Pinus roxburghii is limited to packing cases, crates, shutters, door and window frame, carpentry and joinery items due to its nondurable nature. Hence, to promote use of such timber for applications such as decking, cladding and facade elements chemical modification with a combination of citric acid and sodium hypophosphite, and heat treatment were explored to improve its service life. Methods: Chemical modification was performed using a water solution of citric acid (6.9%) and sodium hypophosphite (6.5%) followed by curing at 140°C for 8 hrs. Dimensional stability was determined by estimating the volumetric swelling coefficient and anti-swelling efficiency (ASE) of treated and control samples. Durability against fungus and termites was evaluated using a soil block bioassay and termite mound test as per standard methods. Results: Both chemical modification and heat treatment of P. roxburghii resulted in enhanced dimensional stability and biological durability compared to the untreated controls. Chemical modification and heat treatment resulted in 23.05% and 18.37% volumetric ASE, respectively. Results showed that a highly perishable species became significantly more durable after chemical modification, exhibiting 5–6 times less mass loss by termites in comparison to the controls. Wood samples modified with citric acid showed excellent resistance to both white and brown rot fungi and exhibited 14-15 times less reduction in mass compared with untreated samples. Conclusions: Citric acid chemical modification is an environment friendly process that improved the dimensional stability as well as resistance against biodegradation. These studies may provide valuable inputs to establish this mode of chemical modification as a cost-effective alternative to other chemicals for wood preservation. The concentrations of the chemicals and temperature for fixation may be varied to establish an optimum combination for best output.

Combined Application of Citric Acid and Cr Resistant Microbes Improved Castor Bean Growth and Photosynthesis while It Alleviated Cr Toxicity by Reducing Cr+6 to Cr3.

Chromium is highly harmful to plants because of its detrimental effects on the availability of vital nutrients and secondary metabolites required for proper plant growth and development. A hydroponic experiment was carried out to analyze the effect of citric acid on castor bean plants under chromium stress. Furthermore, the role of two chromium-resistant microorganisms, Bacillus subtilis and Staphylococcus aureus, in reducing Cr toxicity was investigated. Different amounts of chromium (0 µM, 100 µM, 200 µM) and citric acid (0 mM, 2.5 mM, and 5 mM) were used both alone and in combination to analyze the remediation potential. Results showed that elevated amounts of chromium (specifically 200 µM) minimized the growth and biomass because the high concentration of Cr induced the oxidative markers. Exogenous citric acid treatment boosted plant growth and development by improving photosynthesis via enzymes such as superoxide dismutase, guaiacol peroxidase, catalase, and ascorbate peroxidase, which decreased Cr toxicity. The application of citric acid helped the plants to produce a high concentration of antioxidants which countered the oxidants produced due to chromium stress. It revealed that castor bean plants treated with citric acid could offset the stress injuries by decreasing the H2O2, electrolyte leakage, and malondialdehyde levels. The inoculation of plants with bacteria further boosted the plant growth parameters by improving photosynthesis and reducing the chromium-induced toxicity in the plants. The findings demonstrated that the combination of citric acid and metal-resistant bacteria could be a valuable technique for heavy metal remediation and mediating the adverse effects of metal toxicity on plants.

Optimasi Kombinasi Asam Sitrat dan Asam Tartrat sebagai Zat Pengasam pada Tablet Effervescent Ekstrak Ubi Jalar Ungu (Ipomoea batatas L)

Purple sweet potato has the content of anthocyanin compounds that are efficacious as antioxidants. To deliver these efficacious compounds, formulations of effervescent tablets are required as antioxidants with a combination of citric acid and tartrate acid to accelerate the solubility of the drug. The research aims to optimize the combination of citric acid and tartrate acid as a sourgent on effervescent tablets of purple sweet potato extract using the simplex lattice design method. The manufacture of tablets using a direct pumping method with effervescent powder evaluation includes flow rate test, silent angle, compressibility, and powder moisture. Evaluation of tablets includes organoleptic tests, uniformity of tablet weight, hardness, fragility, and soluble time of tablets—data analysis using simplex lattice design software design expert version 10. The results of effervescent powder evaluation include a test of flow rate, quiet angle, compressibility, and moisture of powder in each formula that already meets the requirements. The physical evaluation results on the effervescent tablet weight uniformity test on F3, F4, and F5 have met the requirements. The evaluation of tablet hardness F1 and F2 also meet the requirements. The results of the evaluation of fragility and time dissolve tablets have met the requirements of all formulas. The simplex lattice design analysis results obtained F5 as the most optimal formula with a concentration of citric acid 103.25 mg and tartrate acid 44.25 mg. The combination of citric acid and tartaric acid affects the evaluation of hardness, fragility, and time-soluble effervescent tablets of purple sweet potato extract. The optimal concentration based on simplex lattice design analysis was obtained in F5 with a citric acid concentration of 103.25 mg and tartrate acid of 44.25 mg.

Acidified Biochar as a Soil Amendment to Drought Stressed (Vicia faba L.) Plants: Influences on Growth and Productivity, Nutrient Status, and Water Use Efficiency

Drought is one of the major threats to global food security. Biochar use in agriculture has received much attention and improving it through chemical modification offers a potential approach for enhancing crop productivity. There is still limited knowledge on how acidified biochar influences soil properties, and consequently its influences on the agricultural productivity of drought stressed plants. The water use efficiency (I-WUE) of drought stressed faba beans was investigated through the effects of acidified biochar (ACBio) (a 3:100 (w:w) combination of citric acid and biochar) on soil properties, growth, productivity, nutrient uptake, water productivity (WP), and irrigation. Two field experiments (2016/2017 and 2017/2018) were conducted in saline soil (ECe, 7.2 dS m−1) on faba been plants grown under three irrigation regimes (i.e., 100, 80, and 60% of crop evapotranspiration (ETc)) combined with three levels of ACBio (0, 5, and 10 t ha−1). Plants exposed to water stress presented a significant decrease in plant height, dry matter, leave area, chlorophyll content (SPAD), the quantum efficiency of photosystem II (Fv/Fm, Fv/F0, and PI), water status (membrane stability index and relative water content), and seed yield. Acidified biochar soil incorporation improved soil properties (chemical and physical), plant growth, physiological responses, WP, I-WUE, and contents of N, P, K, and Ca. Results revealed that the application of ACBio at 10 t ha−1 and 5 t ha−1 significantly increased seed yield by 38.7 and 25.8%, respectively, compared to the control. Therefore, ACBio incorporation may find application in the future as a potential soil amendment for improving growth and productivity of faba bean plants under deficit irrigation.

Treatment with an intravaginal gel containing siliceous dioxide, selenite, and citric acid to promote regression of ASC-US, LSIL, ASC-H, HSIL, p16/Ki67 status and improve clearance of hr-HPV in cervical specimens

Objective: An intravaginal gel containing highly dispersed silicon dioxide (SiO2) and an anti-oxidative combination of citric acid and sodium selenite was tested for its ability to promote regression of abnormal cytological findings and its influence on hr-HPV status and tumor markers p16/Ki67 (CINtec® PLUS test).Patients and methods: A control study was performed, including women (n=100) diagnosed with conspicuous cervical smears (ASC-US, LSIL, ASC-H, or HSIL). The gel was applied for 3x28 days. After three months, participants were analyzed for Pap status, hr-HPV strains, and expression of tumor markers p16/Ki67. Three months later, Pap testing and p16/Ki67 analysis were repeated. The results were compared to those of 106 women who met the same inclusion criteria but did not obtain any treatment.Results: After six months, cytological Pap findings were improved in 80.9% of the participants in the treated group, and the clearing of hr-HPV was observed in 53% of cases. Only 5.3% were tested p16/Ki67 positive after six months in comparison to 75.0% at baseline. In the comparison group, 37.1% of the Pap smears and 18.6% of the CinTec results were improved, but no hr-HPV clearance was observed. The improvements were highly significant for the treatment. Conclutions: The vaginal gel containing SiO2 sodium selenite, and citric acid may support the healing of conspicuous cytological findings and clearance of hr-HPV.

Combined citric acid and rosemary extract to maintain the quality of chilled Pacific white shrimp ( Litopenaeus vannamei )

The effect of citric acid (CA) combined with rosemary extract (RE) on post-harvest preservation of Pacific white shrimp (Litopenaeus vannamei) during 8 days of chilled storage was investigated. Changes in microbial, physicochemical and sensory properties of shrimp muscles were all periodically analyzed. The microbial and physicochemical parameters consisted of total viable count (TVC), color difference, pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), texture profile analysis (TPA), intrinsic fluorescence intensity (IFI) and melanosis. Compared to the control, CA and RE treatment alone, results showed that RE and CA had synergistic effects (p < .05) in inhibiting microorganism growth, lipid and protein oxidation, and maintaining sensory and texture profile. CA combined with RE treatment prolonged the shelf life of Pacific white shrimp up to 8 days of storage at 4 ± 1°C. The results indicated that samples immersed in CA combined with RE suggested a promising approach for the preservation of Pacific white shrimp. Novelty impact statement Combination of citric acid and rosemary extract improved the preservative quality without affecting the color of shrimp. Preservative effects of citric acid on shrimps increased in combination with rosemary extract. Citric acid combined with rosemary extract have potential as a bio-preservative on shrimp.

The Effervescent Granule Ethanol Extract of Andaliman Fruits (Zanthoxylum acanthopodium DC.) using Variations of Source Acid and Antioxidant Activity

Andaliman fruit (Zanthoxylum acanthopodium DC.) contain flavonoids that has antioxidantactivity. This study was conducted to obtain the effervescent granules andaliman fruit extract which has the highest antioxidant activity by DPPH free radical scavenging method. Andaliman fruit was extracted in stages using n-hexane, ethyl acetate and 70% ethanol, then dried using freeze drying method. Furthermore, the dry extract of ethanol is formulated using variation acid sources, namely citric acid and tartaric acid. The results showed that the formulas had moisture rate of 2.30 – 3.95%; fl ow rate of 2.53-4.12 g/sec; the particle size distribution with the fi nes &lt;10%; dissolved time &lt; 2 minutes; and a pH value of 5.48-5.65. The results of the antioxidant activity of formula I-III were 74.0; 84.9 and 91.9 ppm respectively. The conclusion of the research showed that the formula I with a combination of citric acid and tartaric acid is a formula that meets the physical quality requirements and has a strong antioxidant activity with IC50 value of 74.0 ppm.

Impact of multi-strain probiotic, citric acid, garlic powder or their combinations on performance, ileal histomorphometry, microbial enumeration and humoral immunity of broiler chickens.

Heat stress, one of the critical obstacles to poultry sector in subtropical and tropical countries, reduces performance, immune response, and animal welfare. This study examined the effect of dietary inclusion of probiotic (PRO), citric acid (CIT), garlic powder (GAR) or their combinations on growth, blood constituents, ileal microflora and morphology and humoral immunity of broiler chickens subjected to cyclic heat stress. Four hundred ninety one-day-old Ross-308 broiler chicks were randomly allocated to 7 groups with 7 replicates of 10 birds each as follows: control (C) group received the basal diet without supplements, PRO, CIT and GAR groups supplemented with 0.5gkg-1 multi-strain probiotic mixture (MPM), citric acid and garlic powder, respectively. PRO-CIT and PRO-GAR groups treated with 0.5gkg-1 MPM, and 0.5gkg-1 citric acid and garlic powder, while CIT-GAR group fed diet with 0.5gkg-1 of citric acid and garlic powder. Results revealed that dietary supplements and their combinations improved (P < 0.001) growth performance and decreased abdominal fat of heat-stressed birds. Dietary supplements decreased (P < 0.01) serum concentrations of cholesterol, triglycerides and LDL, while HDL was elevated (P < 0.05). Feed additives reduced (P < 0.01) ileal enumeration of Escherichia coli and total coliform while Lactobacillus count was increased (P < 0.05) only in MPM-enriched groups. Supplementation of these natural products improved (P < 0.01) ileal architecture while humoral immune response was not significantly influenced except antibody titre against Newcastle disease virus which was increased (P < 0.05) in MPM-supplemented groups. Conclusively, addition of the dietary supplements and their combinations, particularly, probiotic and citric acid combination can improve productive performance, and intestinal flora and histomorphometry of broilers exposed to cyclic heat stress.

Human papillomavirus persistence or clearance after infection in reproductive age. What is the status? Review of the literature and new data of a vaginal gel containing silicate dioxide, citric acid, and selenite.

Cervical cancer, the third most common cancer in women, is caused in nearly all cases by a persistent infection with high-risk types of the human papillomavirus. Although human papillomavirus infections are 80%–90% transient and disappear spontaneously within 24 months, human papillomavirus infections that remain are at risk of developing cervical lesions. Different therapeutical approaches have been tested to promote the regression of low-grade lesions or prevent progression. They include the application of 5-fluorouracil, curcumin, imiquimod, interferons, Vitamin D, and others. Also, the effect of probiotics and vaginal therapy with carboxy-methyl-beta glucan was assessed. Review of the literature and presentation of the last study data are presented. Clearance of high-risk human papillomavirus seemed to be promoted by treatment with a new vaginal gel containing a highly disperse SiO2 and an anti-oxidative combination of citric acid and sodium. This gel showed, after 6 months, an improvement of cytological Pap findings (ASC-US, LSIL, ASC-H, or HSIL) in 80.9% of the participants. Similarly, there was a clearing of hr-human papillomavirus in 53% of cases after 3 months of gel administration. The percentage increased slightly in the non-treated control group from 78.3% at baseline to 83% after 3 months. The percentage of patients who were tested positive for p16/Ki67 reduced from 75% at baseline to 5.3% in the treatment group after 6 months, while the percentage decreased only slightly in the non-treated group (baseline: 91.5%; 6 months: 75.2%). The examined vaginal gel may support the healing of conspicuous cytological findings (ASC-US, LSIL, ASC-H, or HSIL) and clearance of hr-human papillomavirus positive results.

Biomass-formic acid-hydrogen conversion process with improved sustainability and formic acid yield: Combination of citric acid and mechanocatalytic depolymerization

Sustainable and efficient hydrogen production from biomass resources have been highly desired. Here, we report a low-temperature hydrogen production process from lignocellulosic biomass passing through formic acid (the biomass-formic acid-hydrogen conversion process) with improved sustainability and formic acid yield. In the biomass oxidation/hydrolysis step, toxic sulfuric acid has been replaced by sustainable citric acid. In addition, mechanocatalytic depolymerization of biomass has been applied to the biomass pretreatment step, resulting in the remarkable improvement in formic acid yield. In the first step, the citric-acid-impregnated biomass was subjected to a mechanocatalytic depolymerization process for facilitating contact between the substrate and catalysts (MD-CIB). In the second step, the crude formic acid (CF) solution was obtained via combined hydrolysis-oxidation process of the MD-CIB in the presence of dimethyl sulfoxide (DMSO), and hydrogen peroxide (H2O2). The yield of formic acid were measured up to be 50.03%. In the third step, the lignin-free crude formic acid (LCF) solution was recovered by filtration, or distilled formic acid (DF) solution was obtained by distillation of the CF solution. In the final step, hydrogen was generated from LCF or DF solutions through dehydrogenation of formic acid over Pd catalysts supported on amine-functionalized mesoporous silica (KIE-6) with a sodium formate. The turnover frequency (TOF) at 10 min were measured up to be 279.24 mol H2 mol Pd-1h−1. The clean hydrogen, which is produced from biomass passing through formic acid, could be directly applied in fuel cell as an energy source. Our hydrogen production process is expected to be much more efficient, sustainable and economical process for hydrogen production from biomass. In addition, organic acids as a byproduct could be utilized as a platform chemical.

Optimizing the electrochemical performance of Li2MnO3 cathode materials for Li-ion battery using solution combustion synthesis: Higher temperature and longer syntheses improves performance

Li2MnO3 is the parent compound and a component of the well-studied Li-rich Mn-based layered materials (xLi2MnO3·(1−x)LiMO2) for high capacity Li-ion batteries. Different combinations of citric acid fuel and metal nitrates (C/N) were used to optimize the electrochemical performance of Li2MnO3 nanoparticles by the solution combustion synthesis. Thermodynamic modelling and thermogravimmetric analysis show that the variations of C/N molar ratio affected the combustion process and the Li2MnO3 powder characteristics such as morphology and crystallinity. The fuel-rich composition (C/N = 0.555) with the highest adiabatic flame temperature produced Li2MnO3 cathode materials with the best electrochemical performance. The influence of sintering temperature on the crystallinity of the Li2MnO3 sample was investigated with high-temperature synchrotron XRD. The Li2MnO3 synthesized at a lower temperature (400 °C) had a better initial discharge capacity than the one synthesized at a much higher temperature (800 °C) however, it showed far poorer cycling stability. These differences in their electrochemical performance were explained on the basis of their microstructure and morphology. Furthermore, increasing annealing time at 800 °C (from 2 to 20 h) achieved phase pure materials and improved the electrochemical performance of Li2MnO3 powders. This improvement was due to the well defined, developed and larger particles of the samples annealed at longer times. The results show that apart from increasing synthesis temperature, varying annealing times at optimum temperature could be used to improve the functional performance of ceramic oxides.

Synergistic bactericidal effect of hot water with citric acid against Escherichia coli O157:H7 biofilm formed on stainless steel

This study investigated the antimicrobial effect of hot water with citric acid against Escherichia coli O157:H7 biofilm on stainless steel (SS). Hot water (50, 60, or 70 °C) with 2% citric acid exhibited a synergistic bactericidal effect on the pathogen biofilm. It was revealed that hot water and citric acid combination induced sub-lethally injured cells. Additionally, mechanisms of the synergistic bactericidal effects of hot water with citric acid were identified through several approaches. In terms of biofilm matrix, hot water removes exopolysaccharides, a major component of extracellular polymeric substances (EPS), thereby increasing contact between surface cells and citric acid, resulting in a synergistic bactericidal effect. In terms of the cell itself, increased permeability of citric acid through cell membranes destructed by hot water promotes the inactivation of superoxide dismutase (SOD) in E. coli O157:H7, which induce synergistic generation of reactive oxygen species (ROS) which promote inactivation of cell by activating lipid peroxidation, resulting in destruction of the cell membrane. Therefore, it is interpreted that when hot water with citric acid is applied to E. coli O157:H7 biofilm, synergy effects on the biofilm matrix and cell itself have a complex interaction with each other, thus causing a dramatic synergistic bactericidal effect.

FUNCTIONAL EDIBLE COATINGS FOR DRIED GUAVA (Psidium guajava L.) SLICES

Edible coating is an economical and effective approach towards maintaining the quality of minimally processed fruits, this concept was applied in the storage of dried guava slices. The objective of this study was to investigate the effectiveness of polysaccharide- and gelatin-based coatings in improving the storage quality of the dried guava slices. Sodium alginate (polysaccharide) and gelatin (protein) were used as the base for this model study, additives such as citric acid and fructooligosaccharide were added. Dried guava slices produced with different edible coatings were stored at 24 and 37.5°C, the browning intensity, antioxidant stability and total plate count in the formulations were monitored for 8 weeks. Browning intensity in dried guava slices was less pronounced when citric acid and fructooligosaccharide were combined and incorporated into the sodium alginate- and gelatin-based formulations (p&lt;0.05). The same combination of ingredients helped in maintaining the antioxidant stability in the dried guava slices with gelatin-based coating. While presence of fructooligosaccharide in both of the sodium alginate- and gelatin-based formulations lowered the microbial load during the storage period (p&lt;0.05). These findings suggest a combination of citric acid and fructooligosaccharide could be an ingredient with multi-functional effects in preserving the quality of dried guava slices.

Combination of citric acid and maltodextrin as bonding agent in sorghum bagasse particleboard

The interest of using natural binder in particleboard production is still the primary concern of many researchers. The use of citric acid as an adhesive has been investigated and show satisfying results, especially in particleboard physical properties. However, the particleboard had low bending strength due to high content of citric acid on the particleboard affected the brittleness of the particles. Therefore, the application of citric acid in particleboard production usually combined with other natural adhesives. In this study, a combination of citric acid (CA) and maltodextrin (MD) was used in the production of sorghum bagasse particleboard with a ratio of 1:1. The particleboard was produced with a target density of 0.8 g/cm3, using 15%, 20%, 25% and 30% CA-MD content, hot-pressed at 200°C and 5 MPa for 8 or 10 minutes. The mixture of citric acid and maltodextrin (1:1) was successfully acting as bonding agent in sorghum bagasse particleboard production, mainly when used at 30% adhesive content. The particleboard modulus of rupture and modulus of elasticity, fulfilled the standard of type 8 particleboard, according to JIS 5908. The particleboard physical properties were excellent, proved by the value of particleboard thickness swelling, which was under 12%. This is due to the superb bonding from the combination of citric acid and maltodextrin, as shown by the internal bond values, which exceeded 0.3 N/mm2, the minimum requirement for type 18 particleboards based on JIS A 5908.

Physicochemical properties and in vitro digestibility of mung-bean starches varying amylose contents under citric acid and hydrothermal treatments

In this study, starches of three mung bean cultivars (Vigna radiata) having different amylose contents were isolated and modified using a combination of citric acid and heat-moisture treatment (CA-HMT) or a combination of citric acid and annealing treatment (CA-ANN). Physicochemical properties and in vitro digestibility of native and treated mung bean starches were investigated. Resistant starch (RS) contents of the high-amylose, medium-amylose and low-amylose starches treated with CA-ANN were 41.1%, 35.7% and 27.1%, respectively, being higher than those treated with CA-HMT or native starches in the same variety. The CA-ANN did not affect the morphology and crystallinity of the starches. However, the starches treated by the CA-HMT were partly gelatinized and had higher degree of relative crystallinity as compared to the native starches. The DP¯s, swelling power, and viscosity of the treated starches were significantly lower than those of the native starches. The high-amylose mung bean starch was greatly affected by the treatments rather than medium- or low-amylose mung bean starch.

Effect of Addition of Citric Acid and Sodium Benzoate on pH and Microbial Profile of Soymilk

Aim: To study the synergistic effect of chemical preservatives on the keeping quality of soymilk.&#x0D; Study Design: Ten soymilk samples were prepared and treated with different concentrations of citric acid and sodium benzoate and stored at ambient conditions.&#x0D; Place and duration of Study: The present study was conducted at the Department of Food Science and Technology, Nnamdi Azikiwe University, Awka between March 2015 and June 2016&#x0D; Methodology: Ten (10) soymilk samples were prepared. Soybean seeds (2 kg) that are free of dirt and stones were weighed and steeped in 4 L of tap water, a 12 h steeping regime was adopted. Each soymilk sample was formulated by adding different concentrations of sodium benzoate and citric acid, while the control sample had no treatment. All soymilk samples were then boiled at 75oC for 15 minutes and stored in storage bottles. Standard microbiological techniques were employed in the isolation and enumeration of potential spoilage organisms in soymilk samples. pH analysis was conducted throughout the storage period.&#x0D; Results: There was a decrease in pH of all soymilk samples with increasing storage time. pH at day 0 ranged between 6.2 to 7.2. Isolated bacteria in 10 soymilk samples included Streptococcus sp., Pseudomonas sp., Proteus sp., Bacillus spp., Staphylococcus aureus, Klebsiella sp., Escherichia coli, and Enterobacter species. However, results obtained showed that soymilk could keep up to 7 days at ambient temperature, encouraging the use of citric acid and sodium benzoate as chemical preservatives.&#x0D; Conclusion: In the present study, preservation of soymilk samples from a combination of citric acid and sodium benzoate which are chemical preservatives was found to be more effective than several organic preservatives. Hence, they represent an alternative source of chemical antimicrobial substances for use in food systems to prevent the growth of food borne microorganisms and extend the shelf-life of processed food.

Synergistic bactericidal effect and mechanism of X-ray irradiation and citric acid combination against food-borne pathogens on spinach leaves

In this study, we investigated the antimicrobial activity of the X-ray irradiation and citric acid (CA) combination against Escherichia coli O157:H7 and Listeria monocytogenes on the surface of spinach leaves and elucidated the mechanisms underlying their synergistic interaction. Upon treatment with 0.3 kGy X-ray irradiation and 1% CA combination, the cell counts of E. coli O157:H7 and L. monocytogenes reduced by 4.23 and 3.69 log CFU/mL on spinach leaves, respectively. The synergistic reduction in the cell counts of E. coli O157:H7 and L. monocytogenes by the combination treatment was 0.95 and 1.14 log units, respectively. The X-ray and CA combination exerts its antimicrobial effect by damaging the bacterial cell membrane and enhancing the generation of intracellular reactive oxygen species in the pathogens. The enhanced bactericidal effect of the combination treatment may not be due to the loss of intracellular enzyme activity. We also evaluated the effect of the combination treatment on the quality attributes of spinach leaves. The combination treatment did not result in adverse changes in color and texture of spinach leaves. These results demonstrate the potential of citric acid and X-ray irradiation combination for decontaminating foodborne pathogens on fresh produce.

Photodynamic therapy using graphene quantum dot derivatives

In this study, we show photodynamic therapy (PDT) by graphene quantum dots (GQDs) and graphene oxide quantum dots (GOQDs) to kill the cancer cells. For PDT, we used GQDs and GOQDs as photosensitizer and 365 ​nm UV tubelight as irradiation source. GQDs/GOQDs are synthesized by electrochemical exfoliation of graphite rod. The electrolyte used was a combination of citric acid, NaOH and H2O2 in different proportion. The GQDs and GOQDs with the size range of 1.5–5.5 ​nm, show excitation dependent PL behavior. GQDs/GOQDs show strong absorbance in UV region, exhibit excitation dependent photoluminescence behavior ranging from UV to visible region and show singlet oxygen generation. GQDs/GOQDs show very low cytotoxicity towards skin cancer (B16F10) cells and breast cancer (MCF-7) cells. GQDs/GOQDs show easy cellular uptake and are well distributed inside the cells. Singlet oxygen generation, low cytotoxicity and easy cellular uptake make them a promising candidate for PDT application. PDT is performed on B16F10 ​cells and MCF-7 ​cells using GQDs/GOQDs. More than 90% cells are killed during a short exposure of 5 ​min. However, the cells not treated with GQDs/GOQDs and exposed to irradiation for 5 ​min show that more than 80% cells are alive. The GQD/GOQD PDT has several advantages such as high cell killing efficacy with micro-watt power UV irradiation, less irradiation time and uniform large area exposure. However, the therapy will be limited to skin related cancers as the depth of penetration of UV irradiation is very less.