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PubMed1989

[The use of ionizing radiation for the decontamination of salmonella-containing slaughtered broiler chickens and powdered eggs].

The effect of cobalt-60 gamma irradiation was investigated on the concentration of Salmonella (S.) typhimurium in artificial contaminated chicken carcasses and on the number of S. tennessee and S. agona in artificial contaminated spray-dried whole egg powder and liquid whole egg. Irradiation of carcasses and of liquid whole egg was carried out at deep frozen conditions between -10 degrees C and -18 degrees C and whole egg powder at 15-20 degrees C. The irradiation doses used where between 0.05 and 8.0 KGy. The D10-value of S. typhimurium in broiler chicks ranged between 0.57 and 0.74 and of S. agona respectively S. tennessee amounted to 0.95 and 1.07 in spray dried whole egg powder and 0.47 respectively 0.53 in whole egg content. Irradiation causes drastic reduction of physiological microflora in chicken carcasses. By radiation treatment using a dose of 4.0 KGy, germ count reductions by 3-5 decimal powers were achieved. Resistance of microbes increases in following succession: Pseudomonas spp., Salmonella spp., other Enterobacteriaceae spp., Micrococcus spp., Flavobacterium spp., yeasts, Bacillus spp., Streptomyces spp., fungi. Results of microbiological and sensorial examinations allow following conclusions: 1. Irradiation is highly effective against Salmonella. 2. Irradiation dose of 4.0 KGy is able to kill about 1 Million Salmonella bacteria per chicken. This guarantees safe elimination of natural occurring Salmonella bacteria in broiler chicken carcasses. 3. Irradiation of chicken carcasses up to 4.0 KGy causes no injury of quality, however storage longer than 4 months deteriorates sensorial qualities more than of unirradiated carcasses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Development of a laser diffraction method for the determination of the particle size of aerosolised powder formulations.

Impactor data are an essential component of marketing authorisation for new dry powder aerosol formulations. However such data are time-consuming to obtain and therefore impede the rapid screening of pilot formulations. In this phase of development it would be of considerable benefit to employ a technique where data acquisition was more rapid, such as laser diffraction, to predict the fine particle fraction. It was the aim of this study to investigate whether this is a feasible premise. Five different formulations were prepared, each containing 1.5% (w/w) micronised salbutamol base (volume median diameter: 2.42 microm) blended with the sieved fraction (63-90 microm) of one of the following sugars: regular crystalline lactose, spray dried lactose "Zeparox", sorbitol, maltose and dextrose monohydrate. A Perspex box was constructed to contain particles released from a glass inhaler and allow the particles to be measured by laser diffraction at different flow rates. After being validated using monodisperse aerosols, this assembly was then employed to measure the particle size distributions of each powder formulation and its respective sugar carrier at flow rates ranging from 28.3 to 100 l min(-1). Aerodynamic particle size distribution of salbutamol base from each formulation was also measured after aerosolisation at 28.3 l min(-1) from the glass inhaler into an Andersen cascade impactor. The flight of monodisperse particles with diameters (2-6 microm) in the desired size range of dry powders for inhalation could be contained and the size distribution determined by laser diffraction using the assembly at all flow rates investigated. Treatment of the particle size distributions measured by laser diffraction, i.e. examining only the aerosol particles with diameter <60 microm, highlighted the fine fraction (<5 microm) and enabled the aerosolisation of different blends to be feasibly compared at a range of different flow rates. The blends containing the following excipients could be placed in the following order of increasing fine fraction: spray-dried lactose<dextrose<<maltose<lactose<sorbitol. At 28.3 l min(-1) a significant linear correlation was found between the fine fractions measured by laser diffraction and the salbutamol fine fractions determined by inertial impaction (R(2)=87.4%, p=0.02, ANOVA). Therefore, the laser diffraction technique could prove to be an important tool for particle size characterisation of dry powder aerosol formulations.

Aerosols↗
PubMed2003

Micronization of anti-inflammatory drugs for pulmonary delivery by a controlled crystallization process.

Jet-milling as the common way for micronization of drugs shows several disadvantages. Drug powder properties are decisive for pulmonary use because, besides a small particle size, a good deagglomeration behavior is required. In this study, several anti-inflammatory drugs [beclomethasone-17,21-dipropionate (BDP), betamethasone-17-valerate (BV), triamcinolone acetonide, ECU-R2, budesonide, and prednisolone] were micronized by controlled crystallization without any milling processes. First the drug is dissolved in an organic solvent (BDP/BV: 4%; ECU-R2: 1% in acetone) and precipitated by a solvent change method in the presence of a cellulose ether (hydroxypropylmethylcellulose) as stabilizing hydrocolloid. By rapid pouring the solution of hydroxypropylmethylcellulose in water (BDP/BV: 0.005%; ECU-R2: 0.025%) into the drug solution under stirring in a relationship (v/v) of 1:16 (BDP/BV), 1:4 (ECU-R2), the previously molecularly dispersed drug was associated to small particles and stabilized against crystal growth simultaneously. This dispersion was spray-dried, resulting in a drug powder with a uniform particle-size distribution and a drug load of up to 98% (BDP, BV). The mean particle size of the drug was lower than 5 microm in most cases and consequently in the respirable range. Whereas the fine particle fraction (<5 microm, measured without excipients and without an inhalation device) of jet-milled drugs is 9.5 (BDP) or 13.1 (ECU-R2), fine particle fractions of 25.6% (BDP) resp. 78.2% (ECU-R2) are obtained with the spray-dried powders. As the formation of the small crystals requires a rapid solvent change process, the affinity of the hydrocolloid, and a high difference between the solubility in the solvent and nonsolvent, the drug's partition coefficient limits the method as drugs which are more hydrophilic form larger particles.

Administration, Inhalation↗
PubMed1997

Immunological and functional properties of the exudate gum from northwestern Mexican mesquite (Prosopis spp.) in comparison with gum arabic.

A comparison between the fine structural features of exudate gum from mesquite (Prosopis spp.) indigenous to NW Mexico and commercial gum arabic from Acacia spp. was achieved by means of immunological techniques. Their functional properties were compared from the ability to form oil-in-water emulsions and encapsulate cold press orange peel essential oil by spray drying. Fine comparison of the antigenic compounds in both materials against polyclonal rabbit antibodies, showed that the carbohydrate-rich components with slow mobility of mesquite gum are closely related to the faster ones of gum arabic. Also, close identity was observed for the components in the proteic fraction of both gums. Similar tannin concentrations were found in both materials (approximately 0.43%) with only dark coloured samples bearing higher amounts (approximately 1.9%). Gum arabic retained nearly 100% of the quantity of orange peel essential oil emulsified in water before spray drying, while mesquite gum did so for 90.6% of the citrus oil. From these results it is believed that mesquite gum might be a suitable replacement of gum arabic in arid regions of the world were Prosopis trees have widespread occurrence.

Animals↗
PubMed1998

Evaluation of potato proteins on the growth performance of early-weaned pigs.

We conducted five experiments to evaluate conventional and low-glycoalkaloid potato protein (CPP and LGPP, respectively) in diets for early-weaned pigs. In Exp. 1, 150 weanling pigs (initially 4.4 +/- .9 kg and 15.5 +/- 2 d of age) were fed either a control diet containing 3% spray-dried animal plasma (SDAP) or diets with additional SDAP (2.5 or 5% added; 5.5 or 8% total) or CPP (2.6% or 5.1%) substituted on a total lysine basis. From d 0 to 14 after weaning, increasing SDAP increased (linear, P < .05) ADG and ADFI, whereas increasing CCP had no effect on growth performance. In Exp. 2, 180 weanling pigs (initially 5.9 +/- 1.2 kg and 20 +/- 2 d of age) were fed diets containing a LGPP replacing 25, 50, 75, or 100% of the 7% dietary SDAP on a digestible lysine basis. From d 0 to 7 after weaning, increasing LGPP increased and then returned to control levels ADG and ADFI (quadratic, P < .01) and gain:feed ratio (quadratic, P < .05). In Exp. 3, 175 weanling pigs (initially 5.5 +/- 1.1 kg and 20 +/- 3 d of age) were fed either a control diet containing 20% dried whey, 17.5% dried skim milk, and 4% select menhaden fish meal (SMFM) or diets consisting of lactose and either 3.5 and 7.0% SDAP or 4.0 and 8.0% LGPP added at the expense of dried skim milk on a digestible lysine basis. From d 0 to 7 after weaning, ADG and ADFI increased (linear, P < .05) with increasing SDAP. With increasing LGPP, ADG and ADFI increased and then decreased (quadratic, P < .10 and P < .05, respectively). Gain:feed ratio (G/F) was not affected by SDAP and was improved (linear, P < .05) for pigs fed increasing LGPP. In Exp. 4, 270 weanling pigs (initially 6.2 +/- 1.6 kg and 20 +/- 3 d of age) were used to compare three diets that contained either 2.5% spray-dried blood meal (SDBM), 4.8% SMFM, or 3.92% CPP; test feedstuffs were substituted on a total lysine basis and diets were fed from d 7 to 28 after weaning. Pigs fed CPP had decreased (P < .05) ADG and G/F compared with those fed the other protein sources. In Exp. 5, 255 weanling pigs (initially 5.3 +/- 1.2 kg and 17 +/- 2 d of age), were used to compare five diets that contained either 2.5% SDBM, 5.51% SMFM, 4.17% CPP, 4.17% LGPP or 8.34% LGPP; feedstuffs were substituted on a digestible lysine basis and diets were fed from d 7 to 28 after weaning. No differences (P > .10) were observed in growth performance among pigs fed any of the protein sources within the experiment. However, pigs fed the LGPP had numerically greater ADG and better G/F than those fed CPP. In conclusion, these results suggest that LGPP can be an effective replacement for a portion of the SDAP in diets for weanling pigs.

Amino Acids↗
PubMed2003

Alkaline chitosan solutions.

Rigid and transparent hydrogels were obtained upon pouring chitosan salt solutions into saturated ammonium hydrogen carbonate. Incubation at 20 degrees C for 5 days yielded chitosan carbamate ammonium salt, Chit-NHCO(2)(-)NH(4)(+) a chemical species that either by hydrolysis or by thermal treatment decomposed to restore chitosan in free amine form. Chitosans of different degrees of acetylation, molecular sizes and origins (squid and crustaceans) were used as hydrochloride, acetate, glycolate, citrate and lactate salts. Their hydrogels obtained in ammonium hydrogen carbonate yielded chitosan solutions at pH values as high as 9.6, from which microspheres of regenerated chitosans were obtained upon spray-drying. These materials had a modest degree of crystallinity depending on the partial acylation that took place at the sprayer temperature (168 degrees C). Citrate could cross-link chitosan and impart insolubility to the microspheres. Chloride on the contrary permitted to prepare microspheres of chitosan in free amine form. By the NH(4)HCO(3) treatment, the cationicity of chitosan could be reversibly masked in view of mixing chitosan with alginate in equimolar ratio without coacervation. The clear and poorly viscous solutions of mixed chitosan carbamate and alginate were spray-dried at 115 degrees C to manufacture chitosan-alginate microspheres having prevailing diameter approx 2 micron.

Alginates↗
PubMed2001

Technical optimisation of redispersible dry emulsions.

Preparation of dry emulsions suitable for tablet processing was examined in this study. Liquid o/w-emulsions were spray dried in a laboratory spray dryer applying hydroxypropylmethylcellulose (HPMC) as a solid carrier and emulsifier. As the lipid phase, fractionated coconut oil was used. The ability of various excipients to increase the density of dry emulsions was investigated. Adding sucrose to the formulation, redispersible dry emulsions with higher density were obtained. The type of rotary atomizer did not affect the dry emulsions containing sucrose nor the rate of rotation of the atomizer applied in the spray drying process. By wet granulation, using ethanol as a binder, free-flowing and compactable dry emulsions were obtained and simultaneously the reconstitution properties were preserved. It was concluded that dry emulsions could be optimised for tablet processing by wet granulation. Tablets having a lipid content up to 20% had proper tablet properties.

Emulsions↗
PubMed1999

Microencapsulation of DNA using poly(DL-lactide-co-glycolide): stability issues and release characteristics.

The design of DNA vaccination delivery systems for the targeting of professional antigen presenting cells could be an interesting approach to elicit cytotoxic T-cell responses to fight viral infections and in cancer therapy. Stability studies with linear high and low molecular DNA and supercoiled plasmid DNA were performed in order to check their ability to withstand stress conditions applied during formulation processes. DNA was tested for integrity by the PicoGreen assay and transfectivity was assessed in cell culture transfection experiments. Double-stranded DNA is extremely stable under physiological conditions in vitro but is rapidly degraded under acidic conditions and high shear forces. Thereby, different stress factors resulted in distinct degradation patterns such as fragmentation and strand separation possibly followed by further decomposition of single-stranded DNA. DNA containing PLGA microparticles as a potential delivery system was prepared by spray-drying. Encapsulation efficiency, DNA stability and burst release varied significantly depending on the different parameters explored in this study. The microencapsulation process was altered to achieve maximal stability of encapsulated DNA by reducing exposure to shear forces and by the addition of NaHCO(3) which acts as a buffering agent and furthermore stabilizes dsDNA against mechanical degradation. Stability of DNA is maintained during the burst release phase, but massive degradation occurred during the second release phase possibly due to acidic catalyzed decomposition. In summary, we feel that microencapsulation of DNA vaccines by spray-drying offers manifold possibilities to design suitable delivery systems in terms of optimizing phagocytosis by APCs and maintaining stability of DNA in phagosomes.

Animals↗
PubMed2006

Effect of particle size reduction on dissolution and oral absorption of a poorly water-soluble drug, cilostazol, in beagle dogs.

The purpose of the present study was to investigate the effects of particle size on the dissolution and oral absorption of cilostazol. Three types of suspensions having different particle size distributions were prepared of the hammer-milled, the jet-milled cilostazol crystals and the NanoCrystal spray-dried powder of cilostazol. In vitro dissolution rate of cilostazol was significantly increased by reducing the particle size. The dissolution curves of the cilostazol suspensions were in good agreement with the simulation based on the Noyes-Whitney equation. The bioavailability of cilostazol after oral administration to dogs was increased with reducing the particle size. While positive food effect on the absorption was observed for the suspensions made of the hammer-milled and the jet-milled crystals, no significant food effect was found for the suspension made of the NanoCrystal cilostazol spray-dried powder. These results could be qualitatively predicted from the in vitro dissolution data using the bio-relevant media, FaSSIF and FeSSIF. In conclusion, the NanoCrystal technology is found to be efficient to improve the oral bioavailability of cilostazol and to avoid the food effect on the absorption.

Administration, Oral↗
PubMed2001

Changes in plasma antioxidant status following consumption of diets high or low in fruit and vegetables or following dietary supplementation with an antioxidant mixture.

The aim of the present study was to examine the effect of consumption of a high-fruit and vegetable diet, or a spray-dried extract of selected fruits and vegetables of high antioxidant content, on indices of antioxidant status of individuals consuming a background diet with minimal antioxidant intake. Plasma antioxidant concentrations were determined in twenty-five men following a 2-week depletion period during which they consumed self-selected low-antioxidant diets (less than three servings of fruit and vegetables with no tea, coffee, red wine or fruit juice). Following this period the volunteers consumed either a self-selected diet containing five to seven servings of fruit and vegetables/d, or 30 g of a spray-dried supplement designed to provide the equivalent antioxidant activity of five to seven servings of fruit and vegetables for 2 weeks in a crossover trial. Following consumption of a high-antioxidant diet for 2 weeks, plasma concentrations of ascorbic acid, alpha- and beta-carotene and lutein+zeaxanthin were all significantly increased (P < 0.05) over the depletion period. However, concentrations of lycopene, retinol and tocopherol were not affected. Consumption of the supplement also raised the concentrations of these same antioxidants in plasma. Despite the increases in the concentrations of measured antioxidant nutrients, the 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid-equivalent antioxidant capacity of plasma, as estimated by inhibition of metmyoglobin activity, was not significantly affected by any of the dietary treatments.

Adult↗
PubMed2003

The 3-D model: does time plasticity represent the influence of tableting speed?

The objective of this study is to test the hypothesis that time plasticity (parameter d from 3-D modeling) is influenced by tableting speed. Tablets were produced at different maximum relative densities (rho(rel, max)) on an instrumented eccentric tableting machine and on a linear rotary tableting machine replicator. Some 3-D data plots were prepared using pressure, normalized time, and porosity according to Heckel. After fitting of a twisted plane, the resulting parameters were analyzed in a 3-D parameter plot. The materials used were dicalcium phosphate dihydrate (DCPD), spray-dried lactose, microcrystalline cellulose (MCC), hydroxypropyl methylcellulose (HPMC), kappa-carrageenan (CAR), and theophylline monohydrate (TheoM). The results show that tableting speed especially influences the parameter d (time plasticity) of the 3-D model for plastically and viscoelastically deforming materials such as MCC, HPMC, CAR, and TheoM. For more plastically deforming materials such as MCC, HPMC, and TheoM, a subtle influence on omega is also visible. The stages of higher densification are affected more than the stages of lower densification. Brittle materials such as DCPD exhibit no influence of tableting speed. The influence of speed on spray-dried lactose is minor. The results are valid for data obtained from an eccentric tableting machine and also for data from a linear rotary tableting machine replicator. Thus, the empirically derived parameter time plasticity d really represents the influence of time.

Chemistry, Pharmaceutical↗
PubMed2005

Nasal administration of carbamazepine using chitosan microspheres: in vitro/in vivo studies.

The nasal route is used both for local therapies and, more recently, for the systemic administration of drugs, as well as for the delivery of peptides and vaccines. In this study the nasal administration of Carbamazepine (CBZ) has been studied using microspheres constituted by chitosan hydrochloride (CH) or chitosan glutamate (CG). Blank microspheres were also prepared as a comparison. The microspheres were produced using a spray-drying technique and characterized in terms of morphology (scanning electron microscopy, SEM), drug content, particle size (laser diffraction method) and thermal behaviour (differential scanning calorimetry, DSC). In vitro drug release studies were performed in phosphate buffer (pH 7.0). In vivo tests were carried out in sheep using the microparticles containing chitosan glutamate, chosen on the basis of the results of in vitro studies. The results were compared to those obtained after the nasal administration of CBZ (raw material) alone. For the evaluation of in vivo data statistical analysis was carried out using the unpaired t-test. Spray-drying was a good technique of preparation of CBZ-loaded microspheres. The loading of the drug into the polymeric network always led to an increase in the dissolution rate compared to CBZ raw material. The microspheres obtained using chitosan glutamate had the best behaviour both in vitro and in vivo. They increased the drug concentration in the serum when compared to the nasal administration of the pure drug (Cmax 800 and 25 ng/ml for microspheres and pure drug, respectively). The results obtained indicate that the loading of CBZ in chitosan glutamate microspheres increases the amount of the drug absorbed through the nose.

Administration, Intranasal↗
PubMed2005

Development of fast-dissolving tablets of flurbiprofen-cyclodextrin complexes.

The present study was aimed at developing a tablet formulation based on an effective flurbiprofen-cyclodextrin system, able to allow a rapid and complete dissolution of this practically insoluble drug. Three different cyclodextrins were evaluated: the parent beta-cyclodextrin (previously found to be the best partner for the drug among the natural cyclodextrins), and two amorphous, highly soluble beta-cyclodextrin derivatives, i.e., methyl-beta-cyclodextrin and hydroxyethyl-beta-cyclodextrin. Equimolar drug-cyclodextrin binary systems prepared according to five different techniques (physical mixing, kneading, sealed-heating, coevaporation, and colyophilization) were characterized by Differential Scanning Calorimetry, x-ray powder diffractometry, infrared spectroscopy, and optical microscopy and evaluated for solubility and dissolution rate properties. The drug solubility improvement obtained by the different binary systems varied from a minimum of 2.5 times up to a maximum of 120 times, depending on both the cyclodextrin type and the system preparation method. Selected binary systems were used for preparation of direct compression tablets with reduced drug dosage (50 mg). Chitosan and spray-dried lactose, alone or in mixture, were used as excipients. All formulations containing drug-cyclodextrin systems gave a higher drug dissolved amount than the corresponding ones with drug alone (also at a dose of 100 mg); however, the drug dissolution behavior was strongly influenced by formulation factors. For example, for the same drug-cyclodextrin product the time to dissolve 50% drug varied from less than 5 minutes to more than 60 minutes, depending on the excipient used for tableting. In particular, only tablets containing the drug kneaded with methyl-beta-cyclodextrin or colyophilized with beta-cyclodextrin and spray-dried lactose as the only excipient satisfied the requirements of the Food and Drug Administration (FDA) for rapid dissolving tablets, allowing more than 85% drug to be dissolved within 30 minutes. Finally, it can be reasonably expected that the obtained drug dissolution rate improvement will result in an increase of its bioavailability, with the possibility of reducing drug dosage and side effects.

Analgesics↗
PubMed2004

Fish oil stabilisation by microencapsulation with modified cellulose.

Fish oil is the richest dietary source of long-chain omega-3 polyunsaturated fatty acids (PUFA). Stabilisation of omega-3 PUFA against oxidation is an important task in food processing. The ability of modified celluloses to act as microencapsulating agents for fish oil was investigated. Fish oil microcapsules were produced by spray-drying of homogenised emulsions containing modified celluloses and maltodextrin as coating materials. The quality of microcapsules was evaluated by scanning electron microscopy, determination of encapsulation efficiency, peroxide value during storage and solubility in water. Methylocellulose (MC) and hydroxypropyl methylocellulose (HPMC) showed good emulsifying properties. Homogenisation of emulsions resulted in creation of high amount of stable foam. More damage occurred in the powders coated with HPMC. The oil retention level was very high, 98.5% (i.e. up to 400.0 g/kg ready powder). Samples with fish oil content of approximately 500.0 g/kg exhibited more structural damage impairing the stabilisation effect. This study indicates that the use of modified cellulose, especially MC, as a coating material for the preparation of spray-dried fish oil microcapsules improves the stability and the concentration of fish oil in the powder.

Cellulose↗
PubMed2003

Viability of microencapsulated bifidobacteria in simulated gastric juice and bile solution.

Microencapsulated cells of Bifidobacterium longum B6 and Bifidobacterium infantis CCRC 14633 were prepared by spray drying the cell suspension containing the test organism and 10% (w/w) of the carrier material of either gelatin, soluble starch, skim milk or gum arabic. Survival of these microencapsulated and free cells of bifidobacteria in simulated gastric juice (pH 2.0 and 3.0) and bile solution (0.5% and 2.0%) was then examined. B. infantis CCRC 14633 was more susceptible than B. longum B6 to the simulated gastric environment and bile solution tested. Microencapsulated bifidobacteria exhibited a lower population reduction than free cells during exposure to simulated gastric environment and bile solution. This phenomenon was most pronounced when the test organism was exposed to gastric juice at pH 2.0 or 2.0% bile solution. Moreover, it was also observed that the protective effect exerted by encapsulation with spray drying varied with the carriers used and the strains of bifidobacteria.

Animals↗
PubMed2004

Cationic stearylamine-containing biodegradable microparticles for DNA delivery.

Technical aspects for preparing a new type of cationic stearylamine (SA)-containing microparticle as a potential drug delivery system for negatively charged therapeutics were investigated. Cationic biodegradable microparticles based on poly(lactide) and poly(lactide-co-glycolide) were prepared upon incorporation of SA either by solvent evaporation or by spray-drying. Water-insoluble SA offers the advantage over other water-soluble cationic compounds that it can be dissolved directly in the organic solution together with the polymers. This facilitated the subsequent preparation of the microparticle formulations. Particle size was controlled by the respective process parameters, resulting in either large polymer aggregates within the range 50-100 micro m or small spherical microparticles within the range 1-10 micro m. The incorporation of SA into the formulations also improved particle characteristics in terms of re-dispersibility, reduced sticking, and particle size uniformity. Both circular plasmid DNA (5 kbp) and linear salmon DNA (0.5 kbp) were efficiently adsorbed to the cationic SA microparticle surfaces. Preliminary tests on the release of DNA from spray-dried SA microparticles showed an immediate burst release, which was followed by a delayed second release phase for more than 4 weeks. The cationic SA microparticles might provide a potential drug-delivery system to improve the efficacy for protein and DNA-type therapeutics.

Amines↗
PubMedDate not supplied

The stability of ascorbic acid microencapsulated in granules of rice starch and in gum arabic.

Ascorbic acid (AA) was microencapsulated by spray drying, using gum arabic and rice starch as covering materials. The AA was dissolved in solutions of the wall material prior to processing. For the rice starch, gelatin was used as a binding agent and recovery was effected with calcium pectate. The morphology of the materials was analysed by optical and scanning electron microscopy, it thus being possible to verify the formation and evaluate the structural characteristics of the microcapsules. The capsules produced with gum arabic were smaller (d50% = 8.0 microns) and with a multimode particle size distribution, whilst uncovered starch capsules containing 1-2% gelatin presented a distribution mainly in the range of 5-40 microns. The capsules recovered with calcium pectate had average diameters 10-15 times greater than those obtained only by spray drying. The stability of the encapsulated materials was studied at room temperature (RH 60-65%) and at 45 degrees C (RH 60-65% and 90.7%). AA microencapsulated in gum arabic was shown to be as stable as free crystalline AA under environmental conditions, whereas that encapsulated in rice starch was less stable. Increasing the amount of the binding agent gelatin increased the stability of the uncovered starch encapsulated AA. Recovery with calcium pectate notably increased the stability of the starch encapsulated AA, as compared to the uncovered samples.

Ascorbic Acid↗
PubMed2003

Carbon dioxide extraction of residual solvents in poly(lactide-co-glycolide) microparticles.

A process for the reduction of residual solvents in spray-dried poly(lactide-co-glycolide) (PLGA)-darbepoetin alfa microparticles was developed using carbon dioxide (CO(2)) as an extraction solvent. CO(2) was investigated in two phase states, liquid and gas. Detrimental effects on encapsulated protein integrity and microparticle morphology were observed with liquid CO(2) exposure. Extraction with CO(2) gas at <100 psig reduced residual solvent concentration and particle agglomeration was limited. Extraction rates and particle agglomeration increased with higher CO(2) gas pressures. The CO(2) pressures below which particles of polylactide (PLA) and PLGA microparticles significantly agglomerated were determined and the data used to develop extraction cycles. Extraction cycles were developed in which CO(2) gas pressure was increased as residual solvent concentration decreased in order to keep extraction rates high throughout the cycle. Spray dried darbepoetin alfa-PLGA microparticles were extracted with CO(2) gas and characterized for residual solvent concentration, process yield, particle size distribution, morphology, and protein integrity. The results indicated CO(2) gas may be used to reduce residual solvent to approximately 200 ppm with no significant detrimental effects on protein integrity or microparticle morphology.

Carbon Dioxide↗