Lemon juice improves the extractability and quality characteristics of pectin from yellow passion fruit by-product as compared with commercial citric acid extractant

An environment-friendly procedure, allowing the extraction of safe pectin products with good functional properties from yellow passion fruit by-product, was developed using two natural acid extractants, namely, pure lemon juice and citric acid solvent. The results show that both of them solubilise, from cell wall material, pectins characterised by high galacturonic acid content (64–78% w/w), degree of esterification (52–73), viscosity-average molecular weight (70–95 kDa) and capable of forming gels in the presence of high soluble solids (sucrose) content and acid. However, compared to pure citric acid solvents, lemon natural juice and its concentrate isolate, under similar extraction conditions, pectins of superior quality characteristics, i.e., higher galacturonic acid content, degree of esterification, viscosity-average molecular weight and gelling power.     

Structural characterization, degree of esterification and some gelling properties of Krueo Ma Noy (Cissampelos pareira) pectin

Pectins extracted from Krueo Ma Noy (Cissampelos pareira) leaves mainly consisted of galacturonic acid with trace amount of neutral sugars. The dominant structure of Krueo Ma Noy pectin was established as a 1,4-linked -D-galacturonan by a combination of carboxyl reduction and methylation analysis, and confirmed by FT-IR spectroscopy. The degree of esterification of Krueo Ma Noy pectins was 41.7 and 33.7% for crude and dialyzed pectins, respectively. Krueo Ma Noy pectin has an average molecular weight of 55 kDa, radius of gyration of 15.2 nm and intrinsic viscosity of 2.3 dl/g. Krueo Ma Noy pectin exhibited gelling properties in aqueous solutions at 0.5% (w/v) at 5 °C. Gels were formed at concentrations of 1.0% (w/v) and above even at room temperature. The gel strength, melting point, and melting enthalpy of Krueo Ma Noy pectin increased with polysaccharide concentration.     

Characterization of orange peel pectin and effect of sugars, -ascorbic acid, ammonium persulfate, salts on viscosity of orange peel pectin solutions

The effects of temperature and concentration on the viscosity of orange peel pectin solutions were examined at five different temperatures between 20 and 60°C and five concentration levels between 2.5–20 kg/m³. The effects of temperature was described by an Arrhenius-type equation. The activation energy for viscous flow was in the range 19.53–27.16 kJ/mol, depending on the concentration. The effect of concentration was described by two types of equation, power-law and exponential. Equations were derived which describes the combined effects of temperature and concentration on the viscosity for two different models in the range of temperatures and concentrations studied. Orange peel pectin was extracted by using HCl (pH 2.5, 90°C, 90 min) ammonium oxalate (0.25%, pH 3.5, 75°C, 90 min) and EDTA (0.5%, 90°C, 90 min) extraction procedures. The best result was obtained with ammonium oxalate extraction in which the pectin content of the final product was 30.12%, although the efficiency among the procedures varied.The average molecular weight was measured by light scattering technique. Magnitudes of intrinsic viscosity and molecular weight of pectins obtained by extraction with HCl, ammonium oxalate and EDTA were 0.262, 0.281, 0.309 m³/kg and 84 500, 91 400, 102 800 kg/kgmol, respectively. The molecular weight dependence of the intrinsic viscosity of the orange peel pectin solutions was expressed by Mark–Houwink–Sakurada equation. The data were fitted to equation as η_i=2.34×10⁻⁵(M_w,ave)^0.8224 which helps to evaluate the average molecular weight of pectin solutions from orange peel with a knowledge of their intrinsic viscosity.     

Partial demethylation of oligogalacturonides by pectin methyl esterase 1 is required for eliciting defence responses in wild strawberry (Fragaria vesca)

In addition to the role of the cell wall as a physical barrier against pathogens, some of its constituents, such as pectin-derived oligogalacturonides (OGA), are essential components for elicitation of defence responses. To investigate how modifications of pectin alter defence responses, we expressed the fruit-specific Fragaria  ×  ananassa pectin methyl esterase FaPE1 in the wild strawberry Fragaria vesca . Pectin from transgenic ripe fruits differed from the wild-type with regard to the degree and pattern of methyl esterification, as well as the average size of pectin polymers. Purified oligogalacturonides from the transgenic fruits showed a reduced degree of esterification compared to oligogalacturonides from wild-type fruits. This reduced esterification is necessary to elicit defence responses in strawberry. The transgenic F. vesca lines had constitutively activated pathogen defence responses, resulting in higher resistance to the necrotropic fungus Botrytis cinerea . Further studies in F. vesca and Nicotiana benthamiana leaves showed that the elicitation capacity of the oligogalacturonides is more specific than previously envisaged.     

A comparison of factors influencing citric acid production by Aspergillus niger grown in submerged culture and on filter paper

Summary A filter paper surface cultivation method (previously described as a tool for strain selection by Röhr et al. 1979) was adopted as a cultivation system for citric acid production on a small scale and compared with submerged cultivation. Citric acid production in the submerged system was optimal at defined low concentrations of zinc, ferrous and manganese ions, defined phosphate and nitrogen concentrations and within a defined initial pH. In constrast, citric acid production in the filter paper system was not at all influenced by any of these variables. On the other hand, optimal citrate production in both systems required a high (10%–14%, w/v) sucrose concentration. This identifies sugar concentration as a most significant parameter for citrate production, whereas all other nutritional effects are related to the cultivation system used.     

Optimization of citric acid production from a carrot juice-based medium by <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis> using response surface methodology

In this study, diluted and fortified carrot juice was used for modelling and optimization of citric acid production by a new mutant strain, Yarrowia lipolytica K-168. Protein concentrate obtained from fine flour -a byproduct of semolina production- was used as a nitrogen source in the fermentation medium. Interactive effects of selected independent variables, initial total sugar concentration, initial pH, initial concentration of protein concentrate obtained from fine flour of semolina and temperature, on the growth and citric acid production of the yeast were investigated. An experimental design including 30 experiments was conducted by using the method of central composite design. Modelling the effects of these independent variables on maximum citric acid concentration, maximum citric acid production rate, citric acid yield, the ratio of maximum citric acid concentration to maximum isocitric acid concentration and specific growth rate were performed by response surface methodology. The variations of all of the responses with the independent variables were defined by a quadratic model. Numeric optimization was performed by using the desireability function. The conditions with 190.83 g/L initial sugar concentration, 5.90 initial pH, 0.07 g/L initial concentration of fine flour protein concentrate and 27.86 °C were determined as optimal conditions for citric acid production. The maximum citric acid concentration reached to 80.53 g/L in optimal conditions.     

Enzymatic synthesis of 2-ethylhexyl esters of fatty acids by immobilized lipase from Candida sp. 99–125

The 2-ethylhexyl esters of fatty acids were synthesized by immobilized lipase from Candida sp. 99–125. The reuse stability of immobilized lipase was at least four batches. The conditions of enzymatic synthesis of 2-ethylhexyl palmitate were optimized. In the system of petroleum ether, 10% (w/w) immobilized lipase was used in the esterfication of 2-ethyl hexanol (7.8 mmol) and palmitic acid (7.8 mmol) at 40 °C with silica gel as the water absorbent. The esterification degree was 91% under these conditions. The purity of 2-ethylhexyl palmitate was 98% after purification consisting washing by water and evaporation to remove the organic solvent.     

Modelling on isoamyl isovalerate synthesis from Rhizomucor miehei lipasein organic media: optimization studies

Immobilized lipase from Rhizomucor miehei (Lipozyme IM-20) was employed in the esterification of isovaleric acid and isoamyl alcohol to synthesize isoamyl isovalerate in n-heptane. Response surface methodology (RSM) based on a five-level, five-variable central composite rotatable design (CCRD) was used to evaluate the effects of important variables: enzyme concentration (20–40% w/w of acid), acid concentration (0.2–1.0 M), incubation period (24–120 h), alcohol concentration (0.25–1.25 M) and temperature (30–70 °C) on the esterification yield of isoamyl isovalerate. Extent of conversion was found to be excellent at all acid and alcohol concentrations employed in the range of 0.2–1.25 M, even at low enzyme concentration (20% w/w). The optimum conditions arrived at are as follows: 35% (w/w) enzyme concentration, 1.0 M acid concentration, 1.25 M alcohol concentration and 120 h incubation period, at 35 °C. Under these conditions, the predicted value was 680 mM ester matched very well with an experimental value of 678 mM.     

On the molecular weight of pectic substances and its relation to their gel strengths

A study has been made on the possibility of determining the molecular weight M_w, the second virial coefficient A₂ and the radius of gyration by measuring the light scattering of pectin aqueous solutions. The experimental data were processed on a computer by using an algorithm, accounting for the effect of microgel formations in the pectic solution. A tendency towards a decrease in M_w when decreasing the degree of esterification for a certain type of pectin was established and was confirmed by the change in the intrinsic viscosity [η]. This fact is explained by degradation during deesterification.

The dependence of the gel strength of the pectic preparations on their degree of esterification, molecular weight M_w and purity (p%) was also studied as well as the dependence of the gel strength on the intrinsic viscosity [η], the degree of esterification and the purity p%. The passive multifactor experiment method was used to obtain regression models which were tested for an optimum in the factors influencing the gel strength. The optimal value for the degree of esterification was obtained at 57–58% which confirmed the view that within this range the pectin macromolecules possess maximum conformational flexibility.     

Characterization of hop pectins shows the presence of an arabinogalactan-protein

Hop pectins were extracted from spent hops using acid extraction conditions and were characterized chemically. The acid extraction of spent hops resulted in a yield of 2%, containing 59% of polysaccharides. The hop pectins under investigation had a relatively high molecular weight and an intrinsic viscosity comparable to that of commercially available apple and citrus pectins. The low degree of methyl esterification of these pectins implicates that they are mainly suitable for use in calcium gels. The degree of acetylation and the neutral sugar content were relatively high.

A high molecular weight fraction which contained arabinogalactan-proteins was shown to be present in the hop pectin extract after preparative size-exclusion chromatography. Additionally, a fraction with a lower molecular weight was present containing mainly homogalacturonans. The arabinogalactans in the high molecular weight population consisted of (1→3)- and (1→3,6)-linked galactans highly branched with arabinose and galactose side-chains. The protein part of the arabinogalactan-protein (13%) was found to be rich in cystein, threonin, serinin, alanin, and hydroxyprolin. The molecular weight distribution of the hop pectin after degradation with the enzymes endopolygalacturonase plus pectin methyl esterase suggested that the arabinogalactan-protein present in the hop pectin extract was linked to the pectin and that the arabinogalactan-protein itself had a fairly low molecular weight.     

Oxygen uptake and citric acid production by Candida lipolytica Y 1095

The rates of oxygen uptake and oxygen transfer during cell growth and citric acid production by Candida lipolytica Y 1095 were determined. The maximum cell growth rate, 1.43 g cell/L . h, and volumetric oxygen uptake rate, 343 mg O(2)/L . h, occurred approximately 21 to 22 h after inoculation. At the time of maximum oxygen uptake, the biomass concentration was 1.3% w/v and the specific oxygen uptake rate was slightly greater than 26 mg O(2)/g cell . h. The specific oxygen uptake rate decreased to approximately 3 mg O(2)/g cell . h by the end of the growth phase.During citric acid production, as the concentration of dissolved oxygen was increased from 20% to 80% saturation, the specific oxygen uptake and specific citric acid productivity (mg citric acid/g cell . h) increased by 160% and 71%, respectively, at a biomass concentration of 3% w/v. At a biomass concentration of 5% w/v, the specific oxygen uptake and specific citric acid productivity increased by 230% and 82%, respectively, over the same range of dissolved oxygen concentrations.The effect of dissolved oxygen on citric acid yields and productivities was also determined. Citric acid yields appeared to be independent of dissolved oxygen concentration during the initial production phase; however, volumetric productivity (g citric acid/L . h) increased sharply with an increase in dissolved oxygen. During the second or subsequent production phase, citric acid yields increased by approximately 50%, but productivities decreased by roughly the same percentage due to a loss of cell viability under prolonged nitrogen-deficient conditions. (c) 1994 John Wiley & Sons, Inc.     

Characterization of pectin, flash-extracted from orange albedo by microwave heating, under pressure

Pectin was acid extracted from orange albedo by microwave heating under pressure. Extraction times ranged from 2.5 to 8 min. Solubilized pectin was characterized for molar mass (M), rms radius of gyration (Rg) and intrinsic viscosity [eta] by HPSEC with online light scattering and viscosity detection. M, Rg and [eta] all decreased with increasing extraction time. Nevertheless, at heating times of 2.5 and 3.0 min, M, Rg and [eta] were significantly higher than a commercial citrus pectin when the albedo:solvent ratio was 1:25 (w/v). At the heating time of 2.5 min Mw was 3.6 x 10(5), Rgz was 38 nm and [eta]w was 10.8 dL/g. Chromatography revealed that solubilized pectin distributions were bimodal in nature and that the low-molar-mass fraction increased at the expense of the high-molar-mass fraction with increasing extraction time. Scaling law exponents revealed that the high-molar-mass fraction was extremely compact in shape, whereas the low-molar-mass fraction was more asymmetric in shape. Possibly these results indicated that at short extraction times, pectin was solubilized as compact aggregated network structures that were broken down to their more asymmetric components with increased heating times.     

Deposition of pectin/poly-L-lysine multilayers with pectins of varying degrees of esterification

The effect of pectin esterification on the assembly of multilayers consisting of poly-L-lysine (PLL) and pectin was studied using surface plasmon resonance (SPR), Fourier transform infrared-attenuated total reflection spectroscopy (FTIR-ATR), and a quartz crystal microbalance with dissipation monitoring (QCMD). With each layer deposited, there was a progressive increase in mass. The net charge of the multilayers was positive and increased with increasing degree of esterification of the pectin. Multilayer fabrication involved a limited fractionation of the pectin preparations, with the more highly esterified pectins having a weaker affinity for PLL. The multilayers were relatively hydrated structures with estimates of solids content in the range 10-32% w/w. The more highly esterified pectins had a tendency to form more hydrated structures, which showed a strong deswelling when PLL was added to a freshly deposited pectin layer.     

High-performance liquid chromatographic method for simultaneous determination of hawthorn active components in rat plasma

A simple HPLC method with photodiode-array (PDA) ultraviolet detection was developed for the simultaneous determination of four active polyphenol components of hawthorn (Crataegus), chlorogenic acid, epicatechin, hyperoside and isoquercitrin, in rat plasma. Following extraction from the plasma samples with ethyl acetate–methanol (2:1, v/v), these four compounds were successfully separated using a C₁₈ column with a gradient elution of 5 and 25% acetonitrile in 25 mM phosphate buffer (pH 2.4). The flow-rate was set at 1 ml/min and the eluent was detected at 325 nm for chlorogenic acid, 278 nm for epicatechin, and 360 nm for both hyperoside and isoquercitrin. Narignin (0.82 μg) was used as the internal standard and was detected at 278 nm. The method is linear over the studied range of 0.16–40, 0.63–160, 0.13–32 and 0.13–30 μg/ml for chlorogenic acid, epicatechin, hyperoside and isoquercitrin, respectively. The correlation coefficient for each analyte was greater than 0.995. The intra-day and inter-day precision of the analysis was better than 4 and 7%, respectively. The extraction recoveries at low to high concentration were greater than 85% for both epicatechin and chlorogenic acid, and greater than 94% for both hyperoside and isoquercitrin. The detection limits were 0.04, 0.20, 0.03 and 0.03 μg/ml for chlorogenic acid, epicatechin, hyperoside and isoquercitrin. The developed method was used to analyze the plasma concentrations of the four analytes after the intravenous administration of hawthorn polyphenol extract to rats.     

Pectin extraction in the presence of alcohols

A theoretical discussion of the extraction process and especially of the factors influencing extractant penetration in pectin-containing raw materials is presented. The necessity of adding surfactant in the pectin extraction is proved. Experiments were carried out with two types of apple pressings differing in anhydrouronic acid content and quantity of extractable pectin.

The addition of low molecular alcohols in concentrations from 1% to 3% to the acid extragent resulted in an acceleration of extraction and increase in the pectin yield by 55–90%. Ethylene glycol, glycerol and diethylene glycol had a better effect than monohydric alcohols. The effect of the process duration on the pectin yield during acid extraction was studied. A 25-min extraction was sufficient for taking out the extractable pectin. It was shown that the addition of alcohols resulted in a measurable increase in the pectin gel strength.     

Microcalorimetric studies on the lyophilic properties of pectic substances

The exothermic effects observed on wetting pectins with water and aliphatic alcohols were studied using a microcalorimeter.The heat released on wetting 1 g pectin with water was found to be 171 ± 7·5 J g^?1. It was experimentally established that 1 g of dry pectin exothermically bonded up to 0·57 g of water.By using the Gibbs-Helmholtz-Young equation which relates the heat released by wetting to the area of the wetted surface, it was estimated that the surface accessible to water in 1 g of pectin was 1·46 × 10³ m² g^?1. The heat of hydration was independent of the degree of esterification of the pectin. The experimental results revealed that there were about six molecules of energetically bonded water per monomer unit of pectin.A specific interaction between methanol and the methoxyl groups of pectin was observed on wetting pectins with methanol and dependence was established between the released heat and the degree of esterification. No similar dependence was reported for the remaining aliphatic alcohols.     

Impact of pectin esterification on the antimicrobial activity of nisin‐loaded pectin particles

The relationship between pectin structure and the antimicrobial activity of nisin‐loaded pectin particles was examined. The antimicrobial activity of five different nisin‐loaded pectin particles, i.e., nisin‐loaded high methoxyl pectin, low methoxyl pectin, pectic acid, dodecyl pectin with 5.4 and 25% degree of substitution were tested in the pH range of 4.0–7.0 by agar‐diffusion assay and agar plate count methods. It was found that the degree of esterification of carboxyl group of galacturonic acid in pectin molecule is important for the antimicrobial activity of nisin‐loaded pectin particles. Nisin‐loaded particles prepared using pectic acid or the pectin with low degree of esterification exhibit higher antimicrobial activity than nisin‐loaded high methoxyl pectin particles. Pectins with free carboxyl groups or of low degree of esterification are the most suitable for particles preparation. Moreover, nisin‐loaded pectin particles were active at close to neutral or neutral pH values. Therefore, they could be effectively applied for food preservation. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:245–251, 2017     

Extraction,characterization and spontaneous emulsifying properties of pectin from sugar beet pulp

The effects of organic acid extractants on the yield and characteristics of pectin from sugar beet pulp were investigated with citric acid, malic acid and lactic acid at different pH (1.5 and 2.0) and time (1 h and 2 h). The results demonstrated that the yields of pectins were directly correlated with the decrease of pH and reaction time, and the optimum yield of 17.2% was obtained at pH 1.5 and 2 h. Furthermore, the acid type also affected the physicochemical characteristics of pectin, especially on the esterification degree (42–71), galacturonic acid content (60.2–77.8%), emulsion activity (35.2–40.1%) and emulsion stability (62.1–79.4%), and a relatively single pectin mainly consisted of homogalacturonan could be obtained under a suitable reaction condition, which was an excellent crude material for the production of emulsion activity.     

Determination of artemether and its major metabolite, dihydroartemisinin, in plasma using high-performance liquid chromatography with electrochemical detection

A rapid, selective, sensitive and reproducible HPLC with recutive electrochemical detection for quantitatvie determination of artemether (ART) and its plasma metabolite, dihydroartemisinin (DHA: and β isomers) in plasma is described. The procedure involved the extraction of ART, DHA and the internal standard, artemisinin (ARN) with dichloromethane-tert.-methylbutyl ether (1:1, v/v) or n-butyl chloride-ethyl acetate (9:1, v/v). Chromatographic separation was performed with a mobile phase of acetonitrile-water (20:80, v/v) containing 0.1 M acetic acid pH 5.0, running through a μBondapak CN column. The method was capable of separating the two isomeric forms of DHA (, β). The retention times of -DHA, β-DHA, ARN and ART were 4.6, 5.9, 7.9 and 9.6 min, respectively. Validation of the assay method was performed using both extraction systems. The two extraction systems produced comparable recoveries of the various analytes. The average recoveries of ART, DHA and ARN over the concentration range 80–640 ng/ml were 86–93%. The coefficients of variation were below 10% for all three drugs (ART, -DHA, ARN). The minimum detectable concentrations for ART and -DHA in spiked plasma samples were 5 and 3 ng/ml, respectively. The method was found to be suitable for use in clinical pharmacokinetic study.     

Quantification of some active compounds in air samples at pharmaceutical workplaces by HPLC

Workers involved in the manufacture of drug substances may be exposed to active pharmaceuticals by inhalation of drug dusts or droplets which has been considered the main exposure route. The proposed HPLC method allowed to determine sulpiryde, hydroxyurea and dyprophylline in the concentration range of 0.01–0.187 mg/m³, 0.001–0.08 mg/m³ and 0.01–0.40 mg/m³ for sulpiryde, hydroxyurea and dyprophylline, respectively, when 480 L of air sample was collected on the glass fibre filters. Sulpiryde was extracted with a solvent system consisting of acetonitrile–phosphate buffer at pH 3 (85:15, v/v), while the best efficiency of extraction for hydroxyurea and dyprophylline was achieved using water. HPLC analysis of sulpiryde with fluorescence detection was more sensitive (LOD = 3.1 μg/L) in comparison with UV detection (LOD = 84.4 μg/L).