The interest to sulfonated methyl esters of fatty acids (SME) has been growing during the last decade, because these surfactants are considered as an environmentally friendly and renewable alternative of the linear alkyl-benzene sulfonates (LAS). Here, we present a quantitative study on the properties of aqueous SME solutions, and especially on their surface tension isotherms, critical micelle concentration (CMC) and its dependence on the concentration of added NaCl. It is demonstrated that the CMC of an ionic surfactant determined by electrical conductivity is insensitive to the presence of a small nonionic admixture, so that the CMC values determined by conductivity represent the CMC of the pure surfactant. Using SME as an example, we have demonstrated the application of a new and powerful method for determining the physicochemical parameters of the pure ionic surfactant by theoretical data analysis ("computer purification") if the used surfactant sample contains nonionic admixtures, which are present as a rule. This method involves fits of the experimental data for surface tension and conductivity by a physicochemical model based on a system of mass-balance, chemical-equilibrium and electric-double-layer equations, which allows us to determine the adsorption and micellization parameters of C12-, C14-, C16- and C18-SME, as well the fraction of nonionic admixtures (if any). Having determined these parameters, we can further predict the interfacial and micellization properties of the surfactant solutions, such as surface tension, adsorption, degree of counterion binding, and surface electric potential at every surfactant, salt and co-surfactant concentrations.
This work investigated the underlying formation of acrylamide from amino acids in frying oils during high temperatures and at different times via modeling systems. Eighteen amino acids were used in order to determine which one was more effective on acrylamide production. Significantly the highest amount of acrylamide was produced from asparagine (5987.5µg/kg) and the lowest from phenylalanine (9.25µg/kg). A constant amount of asparagine and glutamine in palm olein and soy bean oils was heated up in modelling system at different temperatures (160, 180 and 200°C) and times (1.5, 3, 4.5, 6, 7.5min). The highest amount of acrylamide was found at 200°C for 7.5min (9317 and 8511µg/kg) and lowest at 160°C for 1.5min (156 and 254µg/kg) in both frying oils and both amino acids. Direct correlations have been found between time (R2=0.884), temperature (R2=0.951) and amount of acrylamide formation, both at p<0.05.
Covering: 2000 up to late 2017This review is focussed upon the acyl-quinic acids, the most studied group within the ca. 400 chlorogenic acids so far reported. The acyl-quinic acids, the first of which was characterised in 1846, are a diverse group of plant-derived compounds produced principally through esterification of an hydroxycinnamic acid and 1l-(-)-quinic acid. Topics addressed in this review include the confusing nomenclature, quantification and characterisation by NMR and MS, biosynthesis and role in planta, and the occurrence of acyl-quinic acids in coffee, their transformation during roasting and delivery to the beverage. Coffee is the major human dietary source world-wide of acyl-quinic acids and consideration is given to their absorption and metabolism in the upper gastrointestinal tract, and the colon where the microbiota play a key role in the formation of catabolites. Evidence on the potential of the in vivo metabolites and catabolites of acyl-quinic acids to promote the consumer's health is evaluated.
Biosynthesis and in vivo depolymerization of intracellular medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) in Pseudomonas putida Bet001 grown on lauric acid were studied. Highest mcl-PHA fraction (>50 % of total biomass) and cell concentration (8 g L-1 ) were obtained at carbon-to-nitrogen (C/N) ratio 20, starting cell concentration 1 g L-1 , and 48 H fermentation. The mcl-PHA comprised of 3-hydroxyhexanoate (C6 ), 3-hydroxyoctanote (C8 ), 3-hydroxydecanoate (C10 ), and 3-hydroxydodecanoate (C12 ) monomers. In vivo action was studied in a mineral liquid medium without carbon source, and in different buffer solutions with varied pH, molarity, ionic strength, and temperature. The monomer liberation rate reflected the mol percentage distribution of the initial polymer subunit composition. Rate and percentage of in vivo depolymerization were highest in 0.2 M Tris-HCl buffer (pH 9, strength = 0.2 M, 30 °C) at 0.21 g L-1 H-1 and 98.6 ± 1.3 wt%, respectively. There is a congruity vis-à-vis to specific buffer type, molarity, pH, ionic strength, and temperature values for superior in vivo depolymerization activities. Direct products from in vivo depolymerization matched the individual monomeric composition of native mcl-PHA. It points to exo-type reaction for the in vivo process, and potential biological route to chiral molecules.
Biocarriers are pivotal in enhancing the reusability of biocatalyst that would otherwise be less economical for industrial application. Ever since the induction of enzymatic technology, varied materials have been assessed for their biocompatibility with enzymes of distinct functionalities. Herein, cellulase was immobilized onto polymethacrylate particles (ICP) as the biocarrier grafted with ethylenediamine (EDA) and glutaraldehyde (GA). Carboxymethyl cellulose (CMC) was used as a model substrate for activity assay. Enzyme immobilization loading was determined by quantifying the dry weight differential of ICP (pre-& post-immobilization). Cellulase was successfully demonstrated to be anchored upon ICP and validated by FTIR spectra analysis. The optimal condition for cellulase immobilization was determined to be pH 6 at 20 °C. The maximum CMCase activity was achieved at pH 5 and 50 °C. Residual activity of ∼50% was retained after three iterations and dipped to ∼18% on following cycle. Also, ICP displayed superior pH adaptability as compared to free cellulase. The specific activity of ICP was 65.14 ± 1.11% relative to similar amount of free cellulase.
Different fractions of fully hydrogenated soybean oil (FHSBO) in soybean oil (10-30% w/w) and the addition of 1% salt (sodium chloride) were used to investigate the effect of high-pressure treatments (HP) on the crystallization behaviors and physical properties of the binary mixtures. Sample microstructure, solid fat content (SFC), thermal and rheological properties were analyzed and compared against a control sample (crystallized under atmospheric condition). The crystallization temperature (Ts) of all model fats under isobaric conditions increased quadratically with pressure until reaching a pressure threshold. As a result of this change, the sample induction time of crystallization (tc) shifted from a range of 2.74-0.82 min to 0.72-0.43 min when sample crystallized above the pressure threshold under adiabatic conditions. At the high solid mass fraction, the addition of salt reduced the pressure threshold to induce crystallization during adiabatic compression. An increase in pressure significantly reduced mean cluster diameter in relation to the reduction of tc regardless of the solid mass fraction. In contrast, the sample macrostructural properties (SFC, storage modulus) were influenced more significantly by solid mass fractions rather than pressure levels. The creation of lipid gel was observed in the HP samples at 10% FHSBO. The changes in crystallization behaviors indicated that high-pressure treatments were more likely to influence crystallization mechanisms at low solid mass fraction.
The formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was investigated using a kinetic study approach as described by first-order, Arrhenius, and Eyring equations. Chemical model systems with different amino acid precursors (proline, phenylalanine, and glycine) were examined at different times (4, 8, 12, and 16 min) and temperatures (150, 180, 210, 240, and 270 °C). PhIP was detected using high-performance liquid chromatography equipped with fluorescence detector (HPLC-FLD). The good fit in first-order suggested that PhIP formation was influenced by the types of amino acids and PhIP concentration significantly increased with time and temperature (up to 240 °C). PhIP was detected in proline and phenylalanine model systems but not in the glycine model system. The phenylalanine model system demonstrated low activation energy (Ea) of 95.36 kJ/mol that resulted in a high rate of PhIP formation (great amount of PhIP formed). Based on the ∆S‡ values both proline and phenylalanine demonstrated bimolecular rate-limiting steps for PhIP formation. Altogether these kinetic results could provide valuable information in predicting the PhIP formation pathway.
Protein solubility is a critical prerequisite to any proteomics analysis. Combination of urea/thiourea and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) have been routinely used to enhance protein solubilization for oil palm proteomics studies in recent years. The goals of these proteomics analysis are essentially to complement the knowledge regarding the regulation networks and mechanisms of the oil palm fatty acid biosynthesis. Through omics integration, the information is able to build a regulatory model to support efforts in improving the economic value and sustainability of palm oil in the global oil and vegetable market. Our study evaluated the utilization of sodium deoxycholate as an alternative solubilization buffer/additive to urea/thiourea and CHAPS. Efficiency of urea/thiourea/CHAPS, urea/CHAPS, urea/sodium deoxycholate and sodium deoxycholate buffers in solubilizing the oil palm (Elaeis guineensis var. Tenera) mesocarp proteins were compared. Based on the protein yields and electrophoretic profile, combination of urea/thiourea/CHAPS were shown to remain a better solubilization buffer and additive, but the differences with sodium deoxycholate buffer was insignificant. A deeper mass spectrometric and statistical analyses on the identified proteins and peptides from all the evaluated solubilization buffers revealed that sodium deoxycholate had increased the number of identified proteins from oil palm mesocarps, enriched their gene ontologies and reduced the number of carbamylated lysine residues by more than 67.0%, compared to urea/thiourea/CHAPS buffer. Although only 62.0% of the total identified proteins were shared between the urea/thiourea/CHAPS and sodium deoxycholate buffers, the importance of the remaining 38.0% proteins depends on the applications. The only observed limitations to the application of sodium deoxycholate in protein solubilization were the interference with protein quantitation and but it could be easily rectified through a 4-fold dilution. All the proteomics data are available via ProteomeXchange with identifier PXD013255. In conclusion, sodium deoxycholate is applicable in the solubilization of proteins extracted from oil palm mesocarps with higher efficiency compared to urea/thiourea/CHAPS buffer. The sodium deoxycholate buffer is more favorable for proteomics analysis due to its proven advantages over urea/thiourea/CHAPS buffer.
The influence of diacylglycerol (DAG) combined with polyglycerol polyricinoleate (PGPR) on the stability of water-in-oil (W/O) emulsions containing hydrogenated palm oil (HPO) was studied. Polarized light microscope revealed that DAG promoted HPO to crystallize at the water-oil interface, providing the combination of Pickering and network stabilization effects. It was proposed that the molecular compatibility of fatty acids in DAG with HPO accounted for the promotional effect. The interfacial crystallization of DAG together with the surface activity of PGPR led to the formation of emulsions with uniform small droplets and high freeze-thaw stability. Further exploration of physical properties indicated that the combination of DAG and PGPR dramatically improved the emulsion's viscoelasticity and obtained a larger deformation yield. Water droplets in DAG-based emulsions acted as active fillers to improve the network rigidity. Therefore, DAG is a promising material to be used as emulsifier to enhance the physical stability of W/O emulsions.
The rate of autooxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) in the presence of micelles formed from mixing equal concentrations of [Cu(C(12)-tmed)Br(2)] (where C(12)-tmed is N,N,N'-trimethyl-N'-dodecylethylenediamine) and several amino acids has been investigated. It was found that the rate in air-saturated solution is very much dependent on pH, which affects the availability of copper(II) coordination site for the catechol and the degree of micellization. At a given pH, the rates in [Cu(C(12)-tmed)Br(2)] micellar media are greatly enhanced in the presence sodium halide.
Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the major polyfluoroalkyl substances (PFASs) contaminating global water environment. This study investigated the efficiency of granular activated carbon (GAC), ultrafiltration (UF) and nanofiltration (NF) treatment for removing PFOS and PFOA contaminants from lake water. NF gave greater removal of all contaminant types (in terms of organic matter, PFOS and PFOA) than GAC treatment which in turn was greater than UF treatment. The lower removal by UF was due to larger pore size of the membrane compared to the size of the target contaminants. For all treatment processes, lower pH (4) in the feedwater showed greater rejection of the organics and selected PFASs. This was likely due to increase in the electrostatic repulsion between solute and sorbent. It could be observed that on increasing the concentration of organics in the feed solution, the rejection of PFOA/PFOS decreased which was due to competition between organics and PFOS/PFOA for binding sites on the membrane/activated carbon surface. It was also noted that protein content led to greater influence for lower rejection of the PFOA/PFOS than carbohydrate or DOC content. This study demonstrated the potential use of membrane processes for removing emerging persistent organic pollutant removal from lake water.
For the synthesis of a highly active TiO2-chitosan nanocomposite, pH plays a crucial role towards controlling its morphology, size, crystallinity, thermal stability, and surface adsorption properties. The presence of chitosan (CS) biopolymer facilitates greater sustainability to the photoexcited electrons and holes on the catalysts' surface. The variation of synthesis pH from 2 to 5 resulted in different physico-chemical and photocatalytic properties, whereby a pH of 3 resulted in TiO2-chitosan nanocomposite with the highest photocatalytic degradation (above 99 %) of methylene orange (MO) dye. This was attributed to the efficient surface absorption properties, high crystallinity, and the presence of reactive surfaces of -NH2 and -OH groups, which enhances the adsorption-photodegradation effect. The larger surface oxygen vacancies coupled with reduced electron-hole recombination further enhanced the photocatalytic activity. It is undeniable that the pH during synthesis is critical towards the development of the properties of the TiO2-chitosan nanocomposite for the enhancement of photocatalytic activity.
A simple and rapid Fourier transform infrared (FTIR) spectroscopic method has been developed for the quantitative determination of malondialdehyde as secondary oxidation product in a palm olein system. The FTIR method was based on a sodium chloride transmission cell and utilised a partial least square statistical approach to derive a calibration model. The frequency region combinations that gave good calibration were 2900-2800, and 1800-1600 cm-1. The precision and accuracy, in the range 0-60 mumol malondialdehyde/kg oil, were comparable to those of the modified distillation method with a coefficient of determination (r2) of 0.9891 and standard error of calibration of 1.49. The calibration was cross-validated and produced an r2 of 0.9786 and standard error of prediction of 2.136. The results showed that the FTIR method is versatile, efficient and accurate, and suitable for routine quality control analysis with the result obtainable in about 2 min from a sample of less than 2 mL.
The investigation of protein-nanoparticle interactions contributes to the understanding of nanoparticle bio-reactivity and creates a database of nanoparticles for use in nanomedicine, nanodiagnosis, and nanotherapy. In this study, hen's egg white was used as the protein source to study the interaction of proteins with sulphuric acid hydrolysed nanocellulose (CNC). Several techniques such as FTIR, zeta potential measurement, UV-vis spectroscopy, compressive strength, TGA, contact angle and FESEM provide valuable information in the protein-CNC interaction study. The presence of a broader peak in the 1600-1050 cm-1 range of CNC/egg white protein FTIR spectrum compared to the 1600-1050 cm-1 range of CNC sample indicated the binding of egg white protein to CNC surface. The contact angle with the glass surface decreased with the addition of CNC to egg white protein. The FESEM EDX spectra showed a higher amount of N and Na on the surface of CNC. It indicates the density of protein molecules higher around CNC. The zeta potential of CNC changed from -26.7 ± 0.46 to -21.7 ± 0.2 with the introduction of egg white protein due to the hydrogen bonding, polar bonds and electrostatic interaction between surface CNC and protein. The compressive strength of the egg white protein films increased from 0.064 ± 0.01 to 0.36 ± 0.02 MPa with increasing the CNC concentration from 0 to 4.73% (w/v). The thermal decomposition temperature of CNC/egg white protein decreased compared to egg white protein thermal decomposition temperature. According to UV-Vis spectroscopy, the far-UV light (207-222nm) absorption peak slightly changed in the CNC/egg white protein spectrum compared to the egg white protein spectrum. Based on the results, the observations of protein nanoparticle interactions provide an additional understanding, besides the theoretical simulations from previous studies. Also, the results indicate to aim CNC for the application of nanomedicine and nanotherapy. A new insight given by us in this research assumes a reasonable solution to these crucial applications.
Preparation of chitosan-coated fatty acid liposomes is often restricted by the solubility of chitosan under basic conditions. In this experiment, the preparation of chitosan-coated oleic acid (OA) liposomes using low molecular weight (LMW) chitosan (10 and 25 kDA) was demonstrated. These selected LMW chitosans are water soluble. The coating of the chitosan layer on OA liposomes was confirmed by its microscope images and physicochemical properties, such as zeta potential and the size of the liposomes. The "peeling off" effect on the surface of chitosan-coated OA liposomes was observed in the atomic force microscope images and showed the occurrence of the chitosan layer on the surface of OA liposomes. The size of the chitosan-coated liposomes was at least 20 nm smaller than the OA liposomes, and the increase of zeta potential with the increasing amount of LMW chitosan further confirmed the presence of the surface modification of OA liposomes.
To determine the diffusion coefficient, water sorption and solubility of various types of restorative dental composites and to evaluate the effect of acidic media (orange juice and coke) on their characteristics.
The relative oxidative stability of freshly prepared and stored liposomal and nanoliposomal systems of docosahexaenoic acid (DHA, 22:6 n-3) and eicosapentaenoic acid (EPA, 20:5 n-3) were investigated. The effects of organic solvents on the oxidative stability of liposomal polyunsaturated fatty acids (PUFAs) produced by two methods, the Bangham thin-film hydration (conventional rotary evaporation method and using organic solvents) and Mozafari (direct hydration and without using organic solvents) methods, were compared. The highest physicochemical stability was observed in PUFA liposomes prepared by the Mozafari method, followed by conventional liposomes and bulk PUFAs. There was no significant change in physicochemical stability during 10 months of cold storage (4°C) in the dark. Moreover, the comparison between liposomes (>200 nm) and nanoliposomes (50-200 nm) revealed that the surface charge, physical stability and oxidative stability of liposomal PUFAs increased as the size of the liposomes decreased. The differences in the oxidative stability of PUFAs may be due to the protective effects of aqueous systems, which indicate the advantage of using non-organic solvent (water and CO(2)) techniques in liposome manufacturing.
Polyhydroxybutyrate (PHB)/polycaprolactone (PCL)/stearate Mg-Al layered double hydroxide (LDH) nanocomposites were prepared via solution casting intercalation method. Coprecipitation method was used to prepare the anionic clay Mg-Al LDH from nitrate salt solution. Modification of nitrate anions by stearate anions between the LDH layers via ion exchange reaction. FTIR spectra showed the presence of carboxylic acid (COOH) group which indicates that stearate anions were successfully intercalated into the Mg-Al LDH. The formation of nanocomposites only involves physical interaction as there are no new functional groups or new bonding formed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the mixtures of nanocomposites are intercalated and exfoliated types. XRD results showed increasing of basal spacing from 8.66 to 32.97 Å in modified stearate Mg-Al LDH, and TEM results revealed that the stearate Mg-Al LDH layers are homogeneously distributed in the PHB/PCL polymer blends matrix. Enhancement in 300% elongation at break and 66% tensile strength in the presence of 1.0 wt % of the stearate Mg-Al LDH as compare with PHB/PCL blends. Scanning electron microscopy (SEM) proved that clay improves compatibility between polymer matrix and the best ratio 80PHB/20PCL/1stearate Mg-Al LDH surface is well dispersed and stretched before it breaks.
Membrane contactors using microporous membranes for acid gas removal have been extensively reviewed and discussed. The microporous membrane acts as a fixed interface between the gas and the liquid phase without dispersing one phase into another that offers a flexible modular and energy efficient device. The gas absorption process can offer a high selectivity and a high driving force for transport even at low concentrations. Using hollow fiber gas-liquid membrane contactors is a promising alternative to conventional gas absorption systems for acid gas capture from gas streams. Important aspects of membrane contactor as an efficient energy devise for acid gas removal including liquid absorbents, membrane characteristics, combination of membrane and absorbent, mass transfer, membrane modules, model development, advantages and disadvantages were critically discussed. In addition, current status and future potential in research and development of gas-liquid membrane contactors for acid gas removal were also briefly discussed.