The influence of coating materials on some properties of alginate beads and survivability of microencapsulated probiotic bacteria

The probiotics, Lactobacillus acidophilus 547, Bifidobacterium bifidum ATCC 1994, and Lactobacillus casei 01, were encapsulated into uncoated calcium alginate beads and the same beads were coated with three types of material, chitosan, sodium alginate, and poly-L-lysine in combination with alginate. The thickness of the alginate beads increased with the addition of coating materials. No differences were detectable in the bead strength by texture analysis or in the thickness of the beads with different types of coating materials by transmission electron microscopy. The survivability of three probiotics in uncoated beads, coated beads, and as free cells (unencapsulated) was conducted in 0.6% bile salt solution and simulated gastric juice (pH 1.55) followed by incubation in simulated intestinal juice with and without 0.6% bile salt. Chitosan-coated alginate beads provided the best protection for L. acidophilus and L. casei in all treatments. However, B. bifidum did not survive the acidic conditions of gastric juice even when encapsulated in coated heads. (C) 2004 Elsevier Ltd. All rights reserved.

Extrusion of mixtures of starch and D-limonene encapsulated with beta-cyclodextrin: Flavour retention and physical properties

d-Limonene was encapsulated with beta-cyclodextrin to improve its retention during pre-added flavour starch extrusion. The objective of this work was to determine the effect of processing condition on the flavour retention and extrudate properties. Corn starch containing five levels of beta-cyclodextrin-d-limonene capsules (0-5%) were extruded at five different maximum barrel temperatures (133-167 degrees C) and screw speeds (158-242 rpm) using a twin screw extruder. The effect of these parameters on the flavour retention, expansion, texture, colour difference (Delta E), Water Absorption Index, Water Solubility Index, and residence time distribution (RTD) were investigated. Barrel temperature and capsule level predominantly influenced flavour retention and extrudate properties, while screw speed primarily affected extruder performances such as torque, die pressure, specific mechanical energy and RTD. (c) 2005 Elsevier Ltd. All rights reserved.

Nano-emulsion production by sonication and microfluidization - A comparison

The efficiency of sonication and microfluidization to produce nano-emulsions were evaluated in this study. The purpose was to produce an oil-in-water nano-emulsion of d-limonene to apply it in the next step for nano-particle encapsulation. In the entrapment and retention of volatiles or for the microencapsulation efficiency, emulsion size is one of the critical factors. In this study, a bench-top sonicator and an air-driven microfluidizer were used to prepare the emulsions. Results show that, while both methods were capable of producing nano-emulsions of the size range of 150-700 nm, the microfluidizer produced emulsions with narrower size distributions and sonication was more convenient in terms of operation and cleaning. In general, the size of the emulsions decreased with increasing sonication time, or the microfluidization pressure and duration. However, for both sonication and microfluidization, optimal conditions were necessary for emulsification beyond which the emulsion sizes would either increase or have little change with further processing.

Survival of probiotics encapsulated in chitosan-coated alginate beads in yoghurt from UHT- and conventionally treated milk during storage

Survival of the microencapsulated probiotics, Lactobacillus acidophilus 547, Bifidobacterium bifidum ATCC 1994, and Lactobacillus casei 01, in stirred yoghurt from UHT- and conventionally treated milk during low temperature storage was investigated. The probiotic cells both as free cells and microencapsulated cells (in alginate beads coated with chitosan) were added into 20 g/100 g total solids stirred yoghurt from UHT-treated milk and 16 g/100 g total solids yoghurt from conventionally treated milk after 3.5 h of fermentation. The products were kept at 4 degrees C for 4 weeks. The survival of encapsulated probiotic bacteria was higher than free cells by approximately 1 log cycle. The number of probiotic bacteria was maintained above the recommended therapeutic minimum (10(7) cfu g(-1)) throughout the storage except for R bifidum. The viabilities of probiotic bacteria in yoghurts from both UHT- and conventionally treated milks were not significantly (P > 0.05) different. (c) 2004 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.

Effect of extrusion parameters on flavour retention, functional and physical properties of mixtures of starch and D-limonene encapsulated in milk protein

The purpose of this research was to investigate the retention of flavour volatiles encapsulated in water-insoluble systems during high temperature–short time extrusion process. A protein precipitation method was used to produce water-insoluble capsules encapsulating limonene, and the capsules were added to the extruder feed material (cornstarch). A twin-screw extruder was used to evaluate the effect of capsule level of addition (0–5%), barrel temperature (125–145 °C) and screw speed (145–175 r.p.m.) on extruder parameters (torque, die pressure, specific mechanical energy, residence time distribution) and extrudate properties [flavour retention, texture, colour, density, expansion, water absorption index, water solubility index (WSI)]. Capsule level had a significant effect on extrusion conditions, flavour retention and extrudate physical properties. Flavour retention increased with the increase in capsule level from 0% to 2.5%, reached a maximum value at capsule level of 2.5% and decreased when the capsule level increased from 2.5% to 5%. The die pressure, torque, expansion ratio, hardness and WSI exhibited the opposite effect with the presence of capsules.

Carbomer-modified spray-dried respirable powders for pulmonary delivery of salbutamol sulphate

The present study investigates the feasibility of using two types of carbomer (971 and 974) to prepare inhalable dry powders that exhibit modified drug release properties. Powders were prepared by spray-drying formulations containing salbutamol sulphate, 20-50% w/w carbomer as a drug release modifier and leucine as an aerosolization enhancer. Following physical characterization of the powders, the aerosolization and dissolution properties of the powders were investigated using a Multi-Stage Liquid Impinger and a modified USP II dissolution apparatus, respectively. All carbomer 974-modified powders and the 20% carbomer 971 powder demonstrated high dispersibility, with emitted doses of at least 80% and fine particle fractions of approximately 40%. The release data indicated that all carbomer-modified powders displayed a sustained release profile, with carbomer 971-modified powders obeying first order kinetics, whereas carbomer 974-modified powders obeyed the Higuchi root time kinetic model; increasing the amount of carbomer 971 in the formulation did not extend the duration of drug release, whereas this was observed for the carbomer 974-modified powders. These powders would be anticipated to deposit predominately in the lower regions of the lung following inhalation and then undergo delayed rather than instantaneous drug release, offering the potential to reduce dosing frequency and improve patient compliance.

The stability of pharmaceutical powders: effect of additives and coating

The decomposition of drugs in the solid state has been studied using aspirin and salsalate as models. The feasibility of using suspension systems for predicting the stability of these drugs in the solid state has been investigated.. It has been found that such systems are inappropriate in defining the effect of excipients on 'the decomposition of the active drug due to chqnges in the degradation pathway. Using a high performance liquid chromatographic method, magnesium stearate was shown to induce the formation of potentlally immunogenic products in aspirin powders. These products which included salicylsalicylic acid .and acetylsalicyclsalicylic acid were not detected in aspirin suspensions which had undergone the same extent of decomposition. By studying the effect of pH and of added excipients on the rate of decomposition of aspirin in suspension systems, it has been shown that excipients such as magnesium stearate containing magnesium oxide, most probably enhance the decomposition of both aspirin and salsalate by alkalinising the aqueous phase. In the solid state, pH effects produced by excipients appear to be relatively unimportant. Evidence is presented to suggest that the critical parameter is a depression in melting point induced by: the added excipient. Microscopical examination in fact showed the formation of clear liquid layers in aspirin samples containing added magnesium stearate but not in control samples. Kinetic equations which take into account both the diffusive barrier presented by the liquid films and the. geometry of the aspirin crystals were developed. Fitting of the .experimental data to these equations showed good agreement. with the postulated theory. Monitorjng of weight issues during the decomposition of aspirin revealed that in the solid systems studied where the bulk of the decomposition product sublimes, it is possible to estimate the extent of degradation from the residual weight, provided the initial weight is known. The corollary is that in such open systems, monitoring of decomposition products is inadequate for assessing the extent of decomposition. In addition to the magnesium stearate-aspirin system, mapyramine maleate-aspirin mixtures were used to model interactive systems. Work carried out in an attempt to stabilise such systems included microencapsulation and film coating. The protection obtained was dependent on the interactive species used. Gelatin for example appeared to stabilise aspirin against the adverse effects of magnesium stearate but increased its decomposition in the presence of mapyramine maleate.

Particulate carriers as immunological adjuvants

In recent years, much interest has focused on the significance of inducing not only systemic immunity but also good local immunity at susceptible mucosal surfaces. A new field of mucosal immunity has been established as information accumulates on gut-associated lymphoid tissue, bronchus-associated lymphoid tissue and nasal-associated lymphoid tissue (GALT, BALT and NALT, respectively) and on their role in both local and systemic immune responses. This project, following the line of investigation started by other workers, was designed to study the use of microspheres to deliver antigens by the mucosal routes (oral and nasal). Antigen-containing microspheres were prepared with PLA and PLGA, by either entrapment within the particles or adsorption onto the surface. The model protein antigens used in this work were mainly tetanus toxoid (TT), bovine serum albumin (BSA) and γ-globulins.In vitro investigations included the study of physicochemical properties of the particulate carriers as well as the assessment of stability of the antigen molecules throughout the formulation procedures. Good loading efficiencies were obtained with both formulation techniques, which did not affect the immunogenicity of the antigens studied. The influence of the surfactant employed on the microspheres' surface properties was demonstrated as well as its implications on the adsorption of proteins. Preparations containing protein adsorbed were shown to be slightly more hydrophobic than empty PLA microspheres, which can enhance the uptake of particles by the antigen presenting cells that prefer to associate with hydrophobic surfaces. Systemic and mucosal immune responses induced upon nasal, oral and intramuscular administration have been assessed and, when appropriate, compared with the most widely used vaccine adjuvant, aluminium hydroxide. The results indicate that association of TT with PLA microspheres through microencapsulation or adsorption procedures led to an enhancement of specific mucosal IgA and IgG and systemic IgG responses to the mucosal delivered antigens. Particularly, nasal administration of TT produced significantly higher serum levels of specific IgG in test animals, as compared to control groups, suggesting that this is a potential route for vaccination. This implies the uptake and transfer of particles through the nasal mucosa, which was further demonstrated by the presence in the blood stream of latex particles as early as 10 min after nasal administration.

Trigger release liposome systems:local and remote controlled delivery?

Target-specific delivery has become an integral area of research in order to increase bioavailability and reduce the toxic effects of drugs. As a drug-delivery option, trigger-release liposomes offer sophisticated targeting and greater control-release capabilities. These are broadly divided into two categories; those that utilise the local environment of the target site where there may be an upregulation in certain enzymes or a change in pH and those liposomes that are triggered by an external physical stimulus such as heat, ultrasound or light. These release mechanisms offer a greater degree of control over when and where the drug is released; furthermore, targeting of diseased tissue is enhanced by incorporation of target-specific components such as antibodies. This review aims to show the development of such trigger release liposome systems and the current research in this field.

Sustained delivery of salbutamol and beclometasone from spray-dried double emulsions

The sustained delivery of multiple agents to the lung offers potential benefits to patients. This study explores the preparation of highly respirable dual-loaded spray-dried double emulsions. Spray-dried powders were produced from water-in-oil-in-water (w/o/w) double emulsions, containing salbutamol sulphate and/or beclometasone dipropionate in varying phases. The double emulsions contained the drug release modifier polylactide co-glycolide (PLGA 50 : 50) in the intermediate organic phase of the original micro-emulsion and low molecular weight chitosan (Mw<190 kDa: emulsion stabilizer) and leucine (aerosolization enhancer) in the tertiary aqueous phase. Following spray-drying resultant powders were physically characterized: with in vitro aerosolization performance and drug release investigated using a Multi-Stage Liquid Impinger and modified USP II dissolution apparatus, respectively. Powders generated were of a respirable size exhibiting emitted doses of over 95% and fine particle fractions of up to 60% of the total loaded dose. Sustained drug release profiles were observed during dissolution for powders containing agents in the primary aqueous and secondary organic phases of the original micro-emulsion; the burst release of agents was witnessed from the tertiary aqueous phase. The novel spray-dried emulsions from this study would be expected to deposit and display sustained release character in the lung.

Transplantation d'îlots de Langerhans microencapsulés : biocompatibilité, survie et fonction

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Transplantation d'îlots de Langerhans microencapsulés : biocompatibilité, survie et fonction

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Effect of experimental parameters on alginate/chitosan microparticles for BCG encapsulation

The aim of the present study was to develop novel Mycobacterium bovis bacille Calmette-Guérin (BCG)-loaded polymeric microparticles with optimized particle surface characteristics and biocompatibility, so that whole live attenuated bacteria could be further used for pre-exposure vaccination against Mycobacterium tuberculosis by the intranasal route. BCG was encapsulated in chitosan and alginate microparticles through three different polyionic complexation methods by high speed stirring. For comparison purposes, similar formulations were prepared with high shear homogenization and sonication. Additional optimization studies were conducted with polymers of different quality specifications in a wide range of pH values, and with three different cryoprotectors. Particle morphology, size distribution, encapsulation efficiency, surface charge, physicochemical properties and biocompatibility were assessed. Particles exhibited a micrometer size and a spherical morphology. Chitosan addition to BCG shifted the bacilli surface charge from negative zeta potential values to strongly positive ones. Chitosan of low molecular weight produced particle suspensions of lower size distribution and higher stability, allowing efficient BCG encapsulation and biocompatibility. Particle formulation consistency was improved when the availability of functional groups from alginate and chitosan was close to stoichiometric proportion. Thus, the herein described microparticulate system constitutes a promising strategy to deliver BCG vaccine by the intranasal route.

Obtenção de extratos de agaricus bisporus com ergosterol para incorporação em iogurtes e procedimentos de microencapsulação

Além de ser o cogumelo mais consumido no mundo, Agaricus bisporus é um dos cogumelos mais ricos em ergosterol, representando esta molécula quase 90% da sua fração de esteróis. Vários estudos têm atribuído ao ergosterol diferentes bioatividades, incluindo efeitos hipocolesterolémicos semelhantes aos exibidos pelos fitoesteróis. Isto torna o ergosterol uma molécula interessante para ser estudada como composto nutracêutico. Assim, este trabalho teve como objetivo avaliar o potencial de utilização dos extratos de A. bisporus ricos em ergosterol na produção de bebidas lácteas funcionais. Para o efeito, foram realizados testes de incorporação do extrato e do ergosterol puro em iogurtes que se compararam com bebidas lácteas funcionais comerciais (aditivadas com fitoesteróis). As amostras de A. bisporus foram submetidas a uma extração assistida por ultrassons e os extratos obtidos (IEXT), bem como a molécula de ergosterol em diferentes concentrações (IERG1 e IERG2), foram incorporados em iogurtes, e comparadas com amostras controlo (amostras de iogurte sem aditivos) (ICN) e iogurtes comerciais contendo fitoesteróis (ICP). Todas as amostras foram analisadas imediatamente após a incorporação (T0), e após sete dias de armazenagem a 4°C (T1), em relação aos parâmetros nutricionais, atividade antioxidante e propriedades citotóxicas em linhas celulares tumorais humanas e numa cultura primária de células de fígado de porco (não tumoral) para avaliação da toxicidade. O teor de ergosterol incorporado na forma pura, ou presente nos extratos, foi monitorizado por HPLC-UV. Adicionalmente, foi realizado um estudo de microencapsulação utilizando a técnica de coacervação, tendo o quitosano e o isolado proteico de soro como materiais encapsulantes. Num ensaio preliminar determinou-se o pH conducente a um maior rendimento de encapsulação e, seguidamente, verificou-se a influência da razão proteína:quitosano (P/Q) e da temperatura utilizada, no rendimento de encapsulação (Y1), na eficiência de encapsulação (Y2) e na carga (teor de ergosterol nas microesferas) (Y3). Posteriormente, o estudo foi realizado baseando-se nas melhores condições para encapsular ergosterol, sendo também avaliadas as respostas Y1, Y2 e Y3. Além de ser o cogumelo mais consumido no mundo, Agaricus bisporus é um dos cogumelos mais ricos em ergosterol, representando esta molécula quase 90% da sua fração de esteróis. Vários estudos têm atribuído ao ergosterol diferentes bioatividades, incluindo efeitos hipocolesterolémicos semelhantes aos exibidos pelos fitoesteróis. Isto torna o ergosterol uma molécula interessante para ser estudada como composto nutracêutico. Assim, este trabalho teve como objetivo avaliar o potencial de utilização dos extratos de A. bisporus ricos em ergosterol na produção de bebidas lácteas funcionais. Para o efeito, foram realizados testes de incorporação do extrato e do ergosterol puro em iogurtes que se compararam com bebidas lácteas funcionais comerciais (aditivadas com fitoesteróis). As amostras de A. bisporus foram submetidas a uma extração assistida por ultrassons e os extratos obtidos (IEXT), bem como a molécula de ergosterol em diferentes concentrações (IERG1 e IERG2), foram incorporados em iogurtes, e comparadas com amostras controlo (amostras de iogurte sem aditivos) (ICN) e iogurtes comerciais contendo fitoesteróis (ICP). Todas as amostras foram analisadas imediatamente após a incorporação (T0), e após sete dias de armazenagem a 4°C (T1), em relação aos parâmetros nutricionais, atividade antioxidante e propriedades citotóxicas em linhas celulares tumorais humanas e numa cultura primária de células de fígado de porco (não tumoral) para avaliação da toxicidade. O teor de ergosterol incorporado na forma pura, ou presente nos extratos, foi monitorizado por HPLC-UV. Adicionalmente, foi realizado um estudo de microencapsulação utilizando a técnica de coacervação, tendo o quitosano e o isolado proteico de soro como materiais encapsulantes. Num ensaio preliminar determinou-se o pH conducente a um maior rendimento de encapsulação e, seguidamente, verificou-se a influência da razão proteína:quitosano (P/Q) e da temperatura utilizada, no rendimento de encapsulação (Y1), na eficiência de encapsulação (Y2) e na carga (teor de ergosterol nas microesferas) (Y3). Posteriormente, o estudo foi realizado baseando-se nas melhores condições para encapsular ergosterol, sendo também avaliadas as respostas Y1, Y2 e Y3. As bebidas funcionalizadas com o extrato (IEXT) e com ergosterol na mesma concentração existente no extrato (IERG1) revelaram uma atividade antioxidante similar às bebidas comerciais com fitoesteróis. No entanto, as bebidas com ergosterol na mesma concentração do extrato de A. bisporus e de fitoesteróis (IERG2) revelaram uma atividade antioxidante superior. Além disso, apenas IEXT, IERG1 e IERG2 apresentaram um aumento na atividade antioxidante de T0 para T1, com destaque para a atividade exibida por IERG2, significando que o ergosterol e os extratos foram capazes de proteger a bebida láctea da oxidação, aumentando a vida de prateleira do produto. IERG2 foi a amostra que revelou a maior citotoxicidade para as linhas celulares tumorais, enquanto as bebidas com fitoesteróis mostraram a menor atividade, sem diferenças significativas entre T0 e T1. Os estudos de microencapsulação revelaram ainda que a técnica de coacervação permite obter cápsulas de distintos tamanhos e que as condições ótimas do processo ocorrem a pH 5,5, com temperatura de 55ºC e razão P/Q de 0,5, com um menor rendimento de encapsulação, mas com uma maior carga em ergosterol. Este trabalho contribuiu para o estudo do potencial da utilização de extratos de A. bisporus com ergosterol no desenvolvimento de novas bebidas funcionais. Constituiu um primeiro passo que necessita de estudos subsequentes relacionados com a avaliação da viabilidade da sua utilização ao nível industrial e demonstração clara da sua bioatividade in vivo.

Utilization of free and microencapsulated Rosmarinus oficinalis L. extracts as bioactives ingredientes for new functional foods developmen

Currently, many consumers search for food with functional characteristics beyond their nutritional properties. Thus, the concept of functional food becomes a hot topic, allowing the obtaining of health benefits, including disease prevention. In this context, plants are recognized as sources of a wide range of bioactives, mainly phenolic compounds. In particular, the Rosmarinus officina/is L., commonly referred as rosemary, has several phenolic compounds with different bioactive properties such as antioxidant, antiinflammatory and antimicrobial activities, among others [!]. Hence, this plant has great potential for incorporation into foods in order to confer bioactivity to the final products. However, it should be highlighted that the bioactive compounds if exposed to adverse environments, for example: light, moisture, extreme pH, storage, food processing conditions, can be degraded leading to the consequent loss of bioactivity [2]. The microencapsulation is an alternative to overcome this problematic of bioactive compounds, as also to ensure controlled release, or target deliver to a specific site [3]. In this work, lyophilized rosemary aqueous extract prepared by in:'usion was used as a functional ingredient for cottage cheeses, after proving that it possesses, both higher content in phenolic compounds and higher antioxidant activity, comparatively with the corresponding hydroethanolic extract. The rosemary aqueous extract revealed, for example, a DPPH scavenging activity with an EC50 value of 73.44±0.54j!g/mL and presented as main phenolic compound the caffeic acid dimer, commonly named as rosmarinic acid. For the functionalized cottage cheeses, a decrease of bioactivity was observed after seven days under storage in fridge, when the extracts were incorporated in its free form. Therefore, to preserve the antioxidant activity, the rosemary aqueous extract was efficiently microencapsulated by using an atomization/coagulation technique and alginate as the matrix material and thereafter incorporated into the cottage cheeses. The final microspheres showed a size, estimated by OM using a magnification of I OOx, ranging between 51.1 and 122.6 J!m and an encapsulation efficiency, estimated through an indirect method, approaching 100%. Overall, the introduction of both free and microencapsulated extracts did not change the nutritional value of cottage cheeses, providing bioactivity that was more preserved with microencapsulated extracts putting in evidence the importance of using microencapsulation to develop effective functional foods.