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In vitro Simulated Digestion and Microstructure of Peppermint Oil Nanoemulsion
Abstract
The variations in average particle size, zeta potential, free fatty acids (FFA) release rate, and the bioavailability of menthol under in vitro simulated digestion conditions of peppermint oil nanoemulsion were investigated. 3D confocal laser scanning microscopy and Cryo-scanning electron microscopy were used to observe the microstructure characteristics of peppermint oil nanoemulsion, which indicated that soybean protein was completely adsorbed at the oil-water interface of the nanoemulsion and presented a core shell structure. And the results indicated that FFA release rate and menthol bioavailability of peppermint oil nanoemulsion prepared by using high-pressure homogenization were much higher. In the simulated gastric digestion phase, the average particle size and the zeta potential of the nanoemulsion increased, and droplet polymerization appeared. After the simulated intestinal, the interfacial protein of nanoemulsion was hydrolyzed, and the oil droplets were digested, which resulted in the decreased particle size and increased absolute value of zeta potential.
The current research aimed to optimize the preparation technology of tributyrin nano-emulsion (TBNE) to improve its digestion properties, which were investigated through digestion models in vitro and in vivo. The content of each component of TBNE was optimized by response surface methodology (RSM) to improve the z-average particle size and stability of TBNE. The optimized TBNE was evaluated for its digestive properties by in vitro and in vivo models. The preparation conditions of TBNE optimized by RSM were as follows: 61.3% of sorbitol, 32.7% of tributyrin, and 6.0% of modified phospholipid (MP). The predicted z-average particle size of TBNE was (246.02 ± 18.10) nm. The results of the verification test showed that the z-average particle size, zeta potential, conductivity, emulsification activity index, and emulsification stability index of TBNE were (250.02 ± 7.18) nm, (−40.23 ± 0.76) mV, (31.80 ± 2.09) μS/cm, (848.00 ± 84.53) min and (1.14 ± 0.02) m²/g, respectively. The in vitro digestion experiment results showed that the TBNE remained stable in the stomach and released in the intestine, while the size of TBNE in the gastrointestinal tact was significantly smaller than that of tributyrin (P < 0.05), which made it easier to be digested and absorbed. Compared with tributyrin treatment, TBNE significantly promoted the average body weight at the 7th d, average daily feed intake, average daily gain, feed/gain, ileum weight, and organ index of ileum of layer chicks (P < 0.05), and the butyric acid content in the ileal chyme from TBNE and tributyrin treatment were 172.18 mg/mL and 100.85 mg/mL (P < 0.01). Therefore, the established TBNE technology in this study could be supposed to improve the digestive properties of tributyrin.
Plant essential oils, a source of biologically active compounds, represent a promising segment in the pharmaceutical market. However, their volatility, hydrophobicity, poor stability, and low toxicity limit direct use in pharmaceutical-related applications. Nanoencapsulation is a technique that allows overcoming these obstacles by improving bioaccessibility and bioavailability. Nanocapsules (NCs) based on biodegradable and biocompatible poly(ɛ-caprolactone) containing Foeniculum vulgare Mill. essential oil (FEO), known for its biological activities, were successfully prepared by interfacial deposition of the preformed polymer method. The composition of FEO (trans-anethole chemotype) was determined by gas chromatography analyses. The FEO presence inside the NCs was confirmed by nuclear magnetic resonance experiments. The FEO-NCs showed nanometer size (210 nm), low polydispersity index (0.10), negative zeta potential (−15 mV), non-Newtonian rheological behavior, and high efficiency of encapsulation (93%). Moreover, parameters such as FEO-NC particle size, bioactive compound retention, and FEO composition were monitored for 30 days at storage temperatures of 4 and 40 °C, confirming the robustness of the nanosystem. Finally, FEO-NCs were resistant to the simulated gastric digestion and showed an effective bioaccessibility of 29% in simulated intestinal digestion. Based on the results obtained, this FEO-NC nanosystem could find interesting applications in the nutraceutical and pharmaceutical sectors.
To prepare a nutritional supplement using silkworm pupae oil (SPO) as a feedstock, a microfluidic reactor with a smart hydrogel immobilized lipase was first constructed to reduce the relative content of palmitic acid at sn-1,3 and improve the nutritional function. The effects of flow rate, reaction temperature, and substrate molar ratio were investigated. In vitro digestion and pH-stat models were employed to analyze the digestion feature after the modification of SPO, while HPLC-ELSD, zeta potential, DSC, and TGA were used to evaluate the nutritional function. The relative content of "OOO" and "OPO" type triglycerides was increased by 49.48% and 107.67%, and that of palmitic acid at sn-1,3 was decreased by 49.61% in 10 s. After the verification of the in vitro digestion model, the fatty acid release rate of the modified SPO was significantly improved by 22.07%, indicating the nutritional function improvement of SPO. Therefore, the nutritional function of SPO has been improved successfully by the application of a microchannel reactor with photo-immobilized lipase, which could set a reference for the utilization of insect oil resources.
The aim of this study was to develop a novel self-nanoemulsifying drug delivery system (SNEDDS) of brigatinib, a poorly soluble anticancer drug, so as to improve its solubility, in vitro release, ex-vivo permeation and anticancer activity. Components of SNEDDS were screened on the basis of maximum solubility of brigatinib. Oleic acid, Tween 20 & diethylene glycol monoethylether were selected as oil phase, emulsifier and co-solvent respectively. Various brigatinib-SNEDDS were developed by spontaneous, low energy, simple mixing method. Developed SNEDDS were optimized on the basis of self-emulsifying capacity, globule size, size distribution, thermodynamic stability and capacity to solubilize maximum amount of brigatinib. The optimized SNEDDS was characterized for physicochemical evaluations such as viscosity, conductivity, pH and refractive index in addition to morphological evaluation of globule size and shape by transmission electron microscopy. The optimized SNEDDS exhibited approximately 205-fold enhancement in the saturation solubility of the brigatinib that resulted in improved in vitro release of drug from SNEDDS as compared to pure drug (P < 0.01). The ex-vivo permeation of brigatinib-SNEDDS across rat intestinal sacs was also improved as compared to pure drug (P < 0.01). The cytotoxic activity of brigatinib-SNEDDS against A549 human lung cancer cell lines during MTT assay were significantly improved as compared to pure brigatinib probably due to improved permeability of the SNEDD loaded brigatinib.
Phosphatidylcholines (PCs) have been widely used in pharmaceutical research. Unfortunately, our understanding of how PCs influence the in vivo lipolysis process of drug delivery systems is still limited. In this study, PCs with fatty acid chains of varying lengths and saturability were used as emulsifiers to prepare curcumin-loaded nanoemulsions (Cur-NEs). The differences in particle size as well as drug and free fatty acid release during the lipolysis process were studied in a simulated blood environment. Furthermore, the pharmacokinetics and antitumor efficacy of Cur-NEs were evaluated in mice. The prepared 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-stabilized Cur-NEs showed similar particle size and stability during storage but exhibited different lipolysis behaviors in vitro and in vivo. Due to the gel state of DPPC in the physiological environment, DPPC-stabilized Cur-NEs had low binding affinity with proteins and maintained their integrity in plasma, leading to sustained drug release, prolonged circulation time and enhanced antitumor efficacy in 4T1 tumor-bearing mice. In contrast, DOPC and DSPC-stabilized Cur-NEs were prone to coalescence in the plasma, resulting in rapid drug release and elimination from circulation. Our findings demonstrated that proper use of PCs is beneficial for obtaining desired transport behavior and drug therapeutic effects, providing guiding principles for rational design of nanodelivery systems.
Understanding and manipulating how emulsion structure impacts on fat digestion is an important step towards understanding the role of fat in our diet. This article reports on the nature of emulsion structuring within the digestive tract and how it affects the dynamics of fat digestion. Emulsions were designed a priori to have specific structuring behaviours (stable, coalesced, partially coalesced and fully broken) under gastrointestinal conditions, through careful emulsifier selection and control of solid fat composition. The impact these structures had on lipolysis was then assessed in vitro using a digestion model and in vivo by measuring the postprandial change in blood triglyceride concentration as a marker of fat absorption. The major factor controlling the rate of fat digestion in vitro was the droplet surface area available for lipase adsorption, which was governed by emulsion instability. The rate of fat absorption in vivo was only affected by large changes in the droplet surface area, and only if these changes remained until the droplets reached the small intestine. This was most evident in emulsions that had undergone extensive partial coalescence under gastric conditions. Partial coalescence resulted in a dramatic reduction in triglyceride absorption, in part because the network of fat crystals provided the agglomerates with an internal scaffold to resist re-dispersion as they passed through the pylorus. The differences in fat absorption profile achieved by controlling emulsion structural stability during digestion provide a basis for examining the physiological effects of food structure on lipid metabolism, which will be the subject of a follow-up clinical paper.
The formation of stable transparent nanoemulsions poses two challenges: the ability to initially create an emulsion where the entire droplet size distribution is below 80 nm, and the subsequent stabilization of this emulsion against Ostwald ripening. The physical properties of the oil phase and the nature of the surfactant layer were found to have a considerable impact on nanoemulsion formation and stabilization. Nanoemulsions made with high viscosity oils, such as long chain triglycerides (LCT), were considerably larger ( D = 120 nm) than nanoemulsions prepared with low viscosity oils such as hexadecane ( D = 80 nm). The optimization of surfactant architecture, and differential viscosity eta D/eta C, has led to the formation of remarkably small nanoemulsions. With average sizes below 40 nm they are some of the smallest homogenized emulsions ever reported. What is more remarkable is that LCT nanoemulsions do not undergo Ostwald ripening and are physically stable for over 3 months. Ostwald ripening is prevented by the large molar volume of long chain triglyceride oils, which makes them insoluble in water thus providing a kinetic barrier to Ostwald ripening. Examination of the Ostwald ripening of mixed oil nanoemulsions found that the entropy gain associated with oil demixing provided a thermodynamic barrier to Ostwald ripening. Not only are the nanoemulsions created in this work some of the smallest reported, but they are also thermodynamically stable to Ostwald ripening when at least 50% of the oil phase is an insoluble triglyceride.
Nano-emulsions consist of fine oil-in-water dispersions, having droplets covering the size range of 100-600 nm. In the present work, nano-emulsions were prepared using the spontaneous emulsification mechanism which occurs when an organic phase and an aqueous phase are mixed. The organic phase is an homogeneous solution of oil, lipophilic surfactant and water-miscible solvent, the aqueous phase consists on hydrophilic surfactant and water. An experimental study of nano-emulsion process optimisation based on the required size distribution was performed in relation with the type of oil, surfactant and the water-miscible solvent. The results showed that the composition of the initial organic phase was of great importance for the spontaneous emulsification process, and so, for the physico-chemical properties of the obtained emulsions. First, oil viscosity and HLB surfactants were changed, alpha-tocopherol, the most viscous oil, gave the smallest droplets size (171 +/- 2 nm), HLB required for the resulting oil-in-water emulsion was superior to 8. Second, the effect of water-solvent miscibility on the emulsification process was studied by decreasing acetone proportion in the organic phase. The solvent-acetone proportion leading to a fine nano-emulsion was fixed at 15/85% (v/v) with EtAc-acetone and 30/70% (v/v) with MEK-acetone mixture. To strength the choice of solvents, physical characteristics were compared, in particular, the auto-inflammation temperature and the flash point. This phase of emulsion optimisation represents an important step in the process of polymeric nanocapsules preparation using nanoprecipitation or interfacial polycondensation combined with spontaneous emulsification technique.
Fatty acid bioavailability can be managed through the physicochemical properties of lipid such as lipid-droplet size, lipid-droplet ultrastructure (lipids organization between core and surface), structure of triglycerides and of phospholipids. The lipid-droplet size exhibits a major effect on lipase activity during lipid digestion. The lipid-droplet ultrastructure is a dynamic factor controling lipase interaction at the lipid interface via the surface phospholipid layer, and also lipase activity via the proportion of triglyceride molecules able to locate at the surface. Triglyceride structure affects in a strong manner digestion, absorption and fatty acid metabolism. Finally, optimal fatty acid transport to specific tissues is dependent on the vehicle molecule (triglyceride or ethyl ester or phospholipid). All these aspects provide convincing support for the possibility of using biotechnologically remodeled lipids with specific physicochemical properties for health benefits.
Essential oils and their volatile constituents are used widely to prevent and treat human disease. The possible role and mode of action of these natural products is discussed with regard to the prevention and treatment of cancer, cardiovascular diseases including atherosclerosis and thrombosis, as well as their bioactivity as antibacterial, antiviral, antioxidants and antidiabetic agents. Their application as natural skin penetration enhancers for transdermal drug delivery and the therapeutic properties of essential oils in aroma and massage therapy will also be outlined.
The influence of excipient nanoemulsions on β-carotene bioaccessibility from commercial dietary supplements (tablets or soft gels) was studied employing an in vitro gastrointestinal tract (GIT) model. Excipient nanoemulsions were formulated from long or medium chain triglycerides (LCT or MCT) to determine the impact of lipid type on carotenoid bioaccessibility. Dietary supplements were tested using the GIT model in the absence or presence of excipient nanoemulsions. β-carotene bioaccessibility from tablets (0.3%) or soft gels (2.4%) was low when tested in isolation. LCT nanoemulsions greatly improved β-carotene bioaccessibility from tablets (20%) and slightly improved it from soft gels (5%), whereas MCT nanoemulsions only slightly improved bioaccessibility. These results were attributed to the ability of large carotenoid molecules to be incorporated into large mixed micelles formed by LCT digestion but not by small ones formed by MCT digestion. Our results indicate that excipient nanoemulsions have considerable potential for improving nutraceutical bioavailability from dietary supplements.
The objective of this study was to understand quantitatively the role that bile salts play in the digestion of emulsified lipids. The behaviours of digestion by pancreatin (1.6 mg/mL) of sodium-caseinate-stabilized emulsions (0.5 wt% protein) and bile-extract-stabilized emulsions (0.2‒5 mg/mL) as influenced by the addition of aqueous bile extract were studied under simulated intestinal conditions (37 °C; pH 7.5; 39 mM K2HPO4, 150 mM NaCl; with continuous agitation at ∼ 150 rev/min for 3 h). The droplet characteristics (size and ζ-potential) of the sodium caseinate- and bile extract-stabilized droplets were evaluated by light scattering techniques. The kinetics of the total fatty acids released by hydrolysis of the emulsified lipids was monitored by the pH-stat method with or without the presence of continuous phase bile extract. The results suggested that the presence of unadsorbed bile extract markedly enhanced the rate and the extent of lipid digestion. This could be attributed to considerable removal of lipolysis products (free fatty acids, mono- and/or di-acylglycerols) in mixed micelles, which are known to inhibit lipid digestion, by the unadsorbed bile salts. This study provides new insights for the lipid digestion of food formulations.
Consumption of essential oils (EOs) and their components, such as eugenol (EU) may reduce chronic disorders, but their use in food is currently limited because of poor solubility and low bioavailability. The aim of this work was to study the influence of carrier oil type, particle size on in vitro lipid digestion and EU release using canola (LCT) and MCT oil-in- 3 water emulsions with different droplet diameters (Coarse > 3000 nm , NE1 > 300 nm and 3 NE2 > 150 nm). There was a progressive increase in the mean particle size of coarse emulsions of both LCT & MCT oils as they passed through simulated gastrointestinal tract consisting of mouth, stomach and intestine phases, which was due to droplet coalescence, flocculation and digestion. However, NE1 and NE2 nanoemulsions showed appreciable increase in particle size after exposure to the simulated intestinal fluid. The rate and extent of in vitro lipid digestion increased with decreasing mean droplet diameter (NE2 ≈ NE1 » 4 Coarse) in both MCT & LCT emulsions. However, MCT emulsions showed faster rate of in vitro lipid digestion which was attributed to more exposure of droplets with the lipase. There 4 was also an appreciable increase in release percentage of eugenol with decreasing droplet diameter (NE2 > NE1 > Coarse) and it was higher in LCT (84%) emulsions which was attributed to large hydrophobic cores that better solubilize EU.
Beta-carotene (BC), the most important dietary source of provitamin A, is necessary for optimum human health. BC is insoluble or only slightly soluble in most liquids but its bioavailability improves when ingested with fat. Therefore lipid emulsions are ideal matrices for BC delivery. BC (0.1%) in corn oil, the dispersed phase (5 or 10%), was homogenized with 2% sodium caseinate solution in a microfluidizer. Homogenization at different pressures produced droplet diameters (Dz = 368-124 nm) that were linear and inversely related to homogenization pressures in the pressure range 10-100 MPa. Nanoemulsions (r < 200 nm) were prepared at 100 MPa. The sodium caseinate emulsions were generally very stable to coalescence or flocculation over 30 days and the slow rate of volume increase was found to be related to the square of the initial droplet radius following Stokes velocity of settling equation. BC stability towards oxidation was lower as droplet diameter decreased. The extent of lipolysis in an in vitro system was higher and linearly related to the inverse of droplet diameter. Bioaccessibility, as defined by the amount of BC recovered in the aqueous phase after ultracentrifugation, was linearly related to smaller emulsion droplet diameter. These results show that sodium caseinate, a food grade emulsifier, can be used to prepare stable emulsions of food oils carrying beta-carotene. Since food oils facilitate the uptake of beta-carotene this may be a preferred system to deliver beta-carotene. Published by Elsevier Ltd.
Blends of polystyrene (PS) and poly (methyl methacrylate) (PMMA) with different surface functionalized multiwall carbon nanotubes (MWNTs) were prepared by solution blending to design materials with tunable EMI (electromagnetic interference) shielding. Different MWNTs like pristine, amine (~NH2) and carboxyl acid (~COOH) functionalized were incorporated in the polymer by solution blending. The specific interaction driven localization of MWNTs in the blend during annealing was monitored using contact mode AFM (atomic force microscopy) on thin films. Surface composition of the phase separated blends was further evaluated using X-ray Photoelectron Spectroscopy (XPS). The localization of MWNTs in a given phase in the bulk was further supported by selective dissolution experiments. Solution casted PS/PMMA (50/50, wt/wt) blend exhibited a co-continuous morphology on annealing for 30 min, whereas on longer annealing times it coarsened into matrix-droplet type of morphology. Interestingly, both pristine MWNTs and NH2-MWNTs resulted in interconnected structures of PMMA in PS matrix upon annealing while, COOH-MWNTs were localized in the PMMA droplets. Room temperature electrical conductivity and electromagnetic shielding effectiveness (SE) were measured in a broad range of frequency. It was observed that both electrical conductivity and SE was strongly contingent on the type of surface functional groups on the MWNTs. The thermal conductivity of the blends was measured with laser flash technique at different temperatures. Interestingly, the SE for blends with pristine and NH2-MWNTs was > 24 dB at room temperature, which is commercially important, and with very marginal variation in thermal conductivity in the temperature range of 303-343 K. The gelation of MWNTs in the blends resulted in a higher SE than those obtained using the composites.
Curcumin, the major curcuminoid compound, is a well-known nutraceutical with many health-promoting properties. Its water insolubility, however, greatly affects its bioaccessibility and thereby bioavailability. The objective of this study was to develop a food-grade curcuminoids organogel with high bioaccessibility and high loading of curcumin. The bioaccessibility was evaluated using in vitro lipolysis experiments. It was shown that medium chain triacylglycerols (MCT) has high digestibility and thus generated high bioaccessibility of curcuminoids. High curcumin loading was achieved by the incorporation of Span 20 in the MCT. Furthermore, monostearin was used as a GRAS (generally recognised as safe) organogelator to form the food-grade organogel, in which the bioaccessibility of curcuminoids was not affected by the gel formation. This newly-developed organogel has the potential to be used for oral delivery of curcuminoids as well as incorporated in functional foods systems.
β-Carotene is an active compound associated with prevention of heart disease, cancer and cataracts. For absorption in vivo, β-carotene must be incorporated in mixed micelles. Micelle formulation varies widely and depends on various factors. The aim of this study was to identify and study the main factors governing the bioaccessibility of β-carotene incorporated into dispersions, using an in vitro digestion model. β-Carotene dispersions were prepared by high-pressure homogenization or by combining emulsification and evaporation. The average particle sizes of the dispersions obtained ranged from 45 to 18315 nm. Results show that the concentration of β-carotene, bile extract and pancreatic lipase, pH, and the particle size of the dispersions significantly affected the transfer of β-carotene from dispersions into micelles. The transfer of β-carotene was inversely related to the particle size and the concentration of bile extract and was highest at pH 6 and 0.4 mg/mL pancreatic lipase. Bile salt played different roles depending on the particle sizes of the dispersion. When the mean diameter of β-carotene particle was below 100 nm, the addition of bile extract and pancreatic lipase did not significantly affect bioaccessibility of β-carotene passing through in vitro digestion model. At larger particle sizes, the transfer efficiency of β-carotene increased with bile extract concentration. The outcomes suggest that there is potential to improve the bioavailability of β-carotene by micronizing lipid droplets.
Curd rheology and calcium distribution in buffalo and cows’ milk, were compared at their natural pH and during acidification (pH 6.5–5.6). Buffalo milk displays a curd structure and rheology different from that of cows’ milk and the casein-bound calcium, as well as the contents of fat, protein and calcium, are also higher. Due to these higher amounts of casein-bound calcium, the overall curd strength with buffalo milk (as indicated by the dynamic moduli) was higher, at similar pH values, than those of equivalent gels produced from cows’ milk. The curd rheology was adversely affected at lower pH (5.8–5.6) in both of the milk types, due to the loss of casein-bound calcium from casein micelles. The degree of solubilisation of calcium in buffalo milk during acidification is quite different from that observed in cows’ milk with a lower proportion of the calcium being solubilised in the former. The maximum curd firmness was obtained at pH 6.0 in both milk types. For both species, these rheological and micellar changes were qualitatively the same but quantitatively different, due to the different milk compositions.
Oil-in-water nanoemulsions containing small lipid droplets (d < 100 nm) are finding increasing applications within the food industry as delivery systems in transparent foods and beverages, and to increase the bioavailability of lipophilic active agents. In this study, we show that nanoemulsions can be fabricated from food-grade ingredients (corn oil, whey protein, and water) using simple processing operations (homogenization, dilution and solvent evaporation). Nanoemulsions were formed by homogenizing 10 wt% organic phase (corn oil and ethyl acetate) with 90 wt% aqueous phase (water and whey protein isolate). The mean particle diameter of the emulsions decreased with increasing ethyl acetate concentration in the organic phase, which was attributed to its ability to alter the size of the droplets produced during homogenization, as well as its ability to be removed from the droplets by dissolution and/or evaporation after homogenization. The particle size also decreased with increasing emulsifier concentration. These nanoemulsions may be useful as delivery systems in the food, pharmaceutical and cosmetics industries.
Every woman and every man has the right to live sexual pleasure therefore sexual education should be scientific and correct.
Sexologists should give teen-agers some important advices to let them approach sexuality without anxiety respecting themselves and the partner.
The orgasm is a normal physiological function of all male and female human beings.
Female orgasm is caused by female erectile organs. The female vagina has little sensitivity and distinguishing clitoral from vaginal orgasm is not correct: it has no scientific basis.
Male and female orgasm should be a normal phase of the sexual response cycle. That is possible with a correct sexual stimulation, also after the menopause.
The male erection is equivalent to the vasocongestion (erection) of the female erectile organs which causes lubrication of the vagina.
To define as “complete sexual intercourse” the case in which the orgasm happens in both partners with or without a penetrative vaginal intercourse.
To teach boys and girls that during the first sexual experience it is not obligatory to have a vaginal intercourse but it is important to give and to receive pleasure caressing and touching the partner. Sexual virginity doesn’t have to be identified anymore by the hymen and first penetration.
Boys and girls should be taught that the size of the male penis is not important to give the partner an orgasm. The contemporary stimulation of the clitoris during vaginal intercourse facilitates the female orgasm.
Sexologists should give correct and scientific sexual education to help people having a satisfactory sexual life.
The interest in incorporating carotenoids, such as β-carotene, into foods and beverages is growing due to their potential health benefits. However, the poor water-solubility and low bioavailability of carotenoids is currently a challenge to their incorporation into many foods. The aim of this work was to study the influence of particle size on lipid digestion and β-carotene bioaccessibility using corn oil-in-water emulsions with different initial droplet diameters: large (d43≈23μm); medium (d43≈0.4μm); and small (d43≈0.2μm). There was a progressive increase in the mean particle size of all the emulsions as they passed through a simulated gastrointestinal tract (GIT) consisting of mouth, stomach, and small intestine phases, which was attributed to droplet coalescence, flocculation, and digestion. The electrical charge on all the lipid particles became highly negative after passage through the GIT due to accumulation of anionic bile salts, phospholipids, and free fatty acids at their surfaces. The rate and extent of lipid digestion increased with decreasing mean droplet diameter (small≈medium≫large), which was attributed to the increase in lipid surface area exposed to pancreatic lipase with decreasing droplet size. There was also an appreciable increase in β-carotene bioaccessibility with decreasing droplet diameter (small>medium>large). These results provide useful information for designing emulsion-based delivery systems for carotenoids for food and pharmaceutical uses.
Like other sectors, recent developments in nanosciences and nanotechnologies are offering lots of new opportunities for innovation to food and related sectors worldwide. Whist developing countries can potentially benefit from these developments, there are also a number of challenges ahead. This concise review provides an account of the main issues emanating from applications of nanotechnologies in food and related sectors with a particular reference to developing countries.
The release and absorption (bioavailability) of carotenoids is a prerequisite for their nutritional impact. This can be strongly affected by the processing conditions used to prepare the food matrix that contains them. To determine the effect of processing on carotenoid bioavailability, homogenized, raw, blanched and cooked carrots were exposed to an in vitro gastric and intestinal digestion model. Final digest samples were placed onto a Caco-2 cell trans-well monolayer culture to mimic intestinal absorption. The results show that the cooked carrot puree consisting of primarily single plant cell particles had the highest release of carotenes, followed by blanched consisting primarily of plant cell clusters and raw carrot puree consisting of larger plant cell clusters. Absorption through the Caco-2 cell layer was the highest from the digesta of cooked carrot puree followed by the digesta of blanched carrot puree. This study demonstrates that thermal processing and/or mechanical homogenization to disrupt plant cell wall matrix enhances the in vitro bioavailability of carotenes from carrots. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
Results of preliminary investigations of the preservation of elemi (E) and peppermint (M) oils in a maltodextrin microcapsule during spray drying of emulsion in a laboratory dryer are discussed. The ratio of maltodextrin to water in the emulsion was 30:70, and the content of each oil 10, 20, and 30 wt·% in relation to maltodextrin. Product quality and results of the process were estimated on the basis of microscopic features of the powder (the shape and size of microparticles) and its density, moisture content and water vapor sorptivity. The efficiency of encapsulation was estimated by specifying the content of essential oil in the product. The compositions of initial oils and the oils contained in the emulsion, inside and on the capsule surface were compared. The positive results of this study justify the necessity of further research and provide a perspective for developing novel technologies.
Electrophoretic profiles, sulfhydryl(SH)/disulfide (SS) groups content, and surface hydrophobicity (H0) values of whey soybean proteins (WSP) and native soy isolates (NSI) were determined. WSP, composed mainly by Kunitz trypsin inhibitor (KTI), and lectin (L), has a H0 value of 24.0 ± 1.0, which is 6.8 times lower than that of NSI ones, and SH/SS groups content in the same range of NSI. The thermal behavior of WSP and NSI was studied by differential scanning calorimetry (DSC). The WSP thermogram in water, similar to NSI, showed two main peaks (Tp values: 74.0 ± 0.5 C and 90.4 ± 0.8C) attributed to thermal denaturation of KTI and L, respectively. These endotherms are slightly affected by μ, whereas those of NSI are strongly affected (Tp of 7S and 11S peaks increase 17C and 20C respectively, by increasing NaCl concentration from 0 to 1M). WSP has low Ho values not noticeably affected by ionic strength changes, whereas NSI has higher Ho, that increase in saline media and favor intermolecular hydrophobic interactions. The consequent low tendency to protein aggregation by hydrophobic interactions in WSP would explain their lower thermal stability at high μ. Control proteins of both preparations (7S and 11S enriched fractions for NSI, and purified trypsin inhibitors, urease and lectin for WSP) were use to confirm these results.
The gelatin/gum Arabic microcapsules encapsulating peppermint oil were prepared by complex coacervation using transglutaminase as hardening agent. The release of microcapsules was investigated in different dispersing media. The release of microcapsules separately followed first order release kinetics model in hot water and zero order release kinetics model in high-temperature oven. The release of microcapsules in hot water exhibited initial rapid release phase and following slow release phase, where effect of core/wall ratio on the release rate was different due to the increase of loading and particle size with the core/wall ratio. The release kinetics rate constant, K, was analyzed by an Arrhenius plot and found to fit well with a linear relation between in ln(K) and 1/T. The activation energy was evaluated to be 32.6 kJ mol−1. The microcapsules were only release about 7% of peppermint oil during the storage of 40 days in cold water, exhibiting excellent storage stability.
The structure of water-in-paraffin oil emulsions stabilized by both cationic surfactant (CTAB) and silicon oxide nanoparticles is investigated. A transition in the geometry of the droplets, which from spherical turns polymorphous, is discussed on the basis of scanning electron microscopy observations. The freeze-fracture technique is employed in addition to a sublimation procedure helping the visualization of the inner structure of the droplets. Their deformation is shown to be a consequence of the interplay between nanoparticles, CTAB and interfacial properties. For polymorphous droplets the existence of a network of self assembled particles bridging them from part to part is evidenced.
In this work, the characteristics of β-carotene nanodispersions prepared with sodium caseinate (SC), Tween 20, decaglycerol monolaurate (ML750) and sucrose fatty acid ester (L1695) using solvent displacement technique were compared. The mean particle size of the nanodispersions ranged from 30 nm to 206 nm, depending on the emulsifier used. SC-stabilized nanodispersions had the largest particles size, while those prepared with Tween 20 had the smallest. The mean particle size and size distribution of the nanodispersions generally remained unchanged after 8 weeks of storage time at 4 °C, but the β-carotene content in all nanodispersions decreased over time. The β-carotene in SC-stabilized nanodispersions was the most stable against oxidation among all samples, most likely due to the small specific surface area of the particles, physical barrier of SC protecting the encapsulated β-carotene against free radicals and the antioxidative activity of caseins. The combined effect of SC and ML750 or L1695 on the mean particle size and β-carotene retention was also investigated. Nanodispersions prepared with SC-ML750 or SC-L1695 showed larger mean particle sizes compared to those prepared with ML750 or L1695 alone. However, the stability of β-carotene in these systems was improved owing to the antioxidative activity of SC. This work demonstrated the importance of emulsifier in determining the characteristics and stability of β-carotene nanodispersions.
The effect of different concentrations (0–1.2% v/v) of mint (Mentha piperita) essential oil on the growth/survival of Salmonella enteritidis and Staphylococcus aureus was studied in nutrient broth, using the viable count method and conductance measurements. In particular the addition of mint essential oil reduced the total viable counts of St. aureus about 6–7 logs while this of S. enteritidis only ca. 3 logs. The detection time measurements showed also that the inhibitory effect of mint essential oil was affected by the incubation temperature as well as by the concentration of essential oil added in the growth medium. At low concentration of essential oil (<0.1%), the addition of glucose in the growth medium prevented the formation of staphylococcal enterotoxin B, while the reduction of viable cells was only 2 logs. This glucose effect was not evident in Salmonella enteritidis samples. The percentage of glucose utilization in the growth medium of both pathogens, was reduced drastically with the addition of essential oil and as a consequence the assimilation or formation of different compounds, such as lactate, formate and acetate in the growth medium was also affected.
A sequential in vitro model of digestion was used to investigate the changes in the physicochemical properties of emulsions during gastrointestinal transit. Oil-in-water emulsions were prepared with whey protein isolate (WPI) or soy protein isolate (SPI) at the same protein concentration (1.5%). Despite pepsinolysis of both proteins during the gastric phase, emulsions stabilized with WPI were more stable compared to those prepared with SPI. For both emulsions, the size of the oil droplets, which plays a critical role in lipid digestion, was extensively altered during the duodenal phase due to the presence of bile salts (BS) and phospholipids (PL). As shown by ζ-potential measurements, the results suggested the displacement of both proteins from the interface by BS; however, the displacement was much faster for the WPI-emulsions. The change in interfacial composition of the oil droplets was significantly affected by inclusion of PL and phospholipase A(2) (PLA(2)) in the in vitro digestion model. The interfacial activity of pancreatic triglyceride lipase (PTL) was markedly affected in the presence of the surface-active compounds present in the digestive fluids, including BS, PL, colipase (COL) and PLA(2). A higher percentage of lipid hydrolysis was obtained in the presence of COL and PLA(2) than with BS alone or mixed BS-PL. SPI-emulsions consistently showed a higher degree of lipolysis compared to the WPI-emulsions regardless of the in vitro digestion model used. The results support the conclusion that the interfacial composition of the original emulsion plays a major role in determining the extent of lipolysis.
Colloidal mixtures containing bile salts (BS), phosphatidylcholine (PC), and medium and long-chain monoglycerides and fatty acids were prepared as model systems to represent typical intestinal contents after digestion of formulation derived lipids under both low (5 mM BS/1.25 mM PC) and high (20 mM BS/5 mM PC) BS and PC conditions. Size-exclusion chromatography of the colloidal species that formed in the medium-chain digests indicated the presence of vesicles, mixed micelles, and simple micelles, whereas the long-chain digests contained only vesicles and mixed micelles. In the long-chain digests the mixed micellar phase was the predominant drug solubilizing species for griseofulvin, danazol, and halofantrine, although for increasingly lipophilic drugs, the vesicular phase contributed an increasing proportion of the solubilization capacity. In contrast, the solubilization capacity of the vesicular phase was predominant in the medium-chain digests, and no clear trends were evident in the relationship between drug lipophilicity and proportional solubilization. These data highlight the need to consider the colloidal species that form in the small intestine during the digestion of common formulation lipids and the coincident enhancement in drug solubilization provided under these circumstances.
As a consequence of modern drug discovery techniques, there has been a consistent increase in the number of new pharmacologically active lipophilic compounds that are poorly water soluble. A great challenge facing the pharmaceutical scientist is making these molecules into orally administered medications with sufficient bioavailability. One of the most popular approaches to improve the oral bioavailability of these molecules is the utilization of a lipid based drug delivery system. Unfortunately, current development strategies in the area of lipid based delivery systems are mostly empirical. Hence, there is a need for a simplified in vitro method to guide the selection of a suitable lipidic vehicle composition and to rationalize the delivery system design. To address this need, a dynamic in vitro lipolysis model, which provides a very good simulation of the in vivo lipid digestion process, has been developed over the past few years. This model has been extensively used for in vitro assessment of different lipid based delivery systems, leading to enhanced understanding of the suitability of different lipids and surfactants as a delivery system for a given poorly water soluble drug candidate. A key goal in the development of the dynamic in vitro lipolysis model has been correlating the in vitro data of various drug-lipidic delivery system combinations to the resultant in vivo drug profile. In this paper, we discuss and review the need for this model, its underlying theory, practice and limitations, and the available data accumulated in the literature. Overall, the dynamic in vitro lipolysis model seems to provide highly useful initial guidelines in the development process of oral lipid based drug delivery systems for poorly water soluble drugs, and it predicts phenomena that occur in the pre-enterocyte stages of the intestinal absorption cascade.