Electrostatic spray drying: A new alternative for drying of complex coacervates.

Complex coacervation can be used for controlled delivery of bioactive compounds (i.e., flaxseed oil and quercetin). This study investigated the co-encapsulation of flaxseed oil and quercetin by complex coacervation using soluble pea protein (SPP) and gum arabic (GA) as shell materials, followed by innovative electrostatic spray drying (ES). The dried system was analyzed through encapsulation efficiency (EE) and yield (EY), morphological and physicochemical properties, and stability for 60 days. Small droplet size emulsions were produced by GA (in the first step of complex coacervation) due to its greater emulsifying activity than SPP. Oil EY and EE, moisture, and water activity in dried compositions ranged from 75.7 to 75.6, 76.0-73.4 %, 3.4-4.1 %, and 0.1-0.2, respectively. Spherical microcapsules were created with small and aggregated particle size but stable for 60 days. An amount of 8 % of quercetin remained in the dried coacervates after 60 days, with low hydroperoxide production. In summary, when GA is used as the emulsifier and SPP as the second biopolymer in the coacervation process, suitable coacervates for food applications are obtained, with ES being a novel alternative to obtain coacervates in powder, with improved stability for encapsulated compounds. As a result, this study helps provide a new delivery system option and sheds light on how the characteristics of biopolymers and the drying process affect coacervate formation.

Microencapsulation of flaxseed oil in pea protein-gum arabic complex coacervates delays lipid digestion in liquid yoghurt.

Flaxseed oil coacervates were produced by complex coacervation using soluble pea protein and gum arabic as shell materials, followed by either spray or electrostatic spray drying and their incorporation to yoghurt. Three yoghurt formulations were prepared: yoghurt with spray-dried microcapsules (Y-SD); with electrospray-dried microcapsules (Y-ES); with the encapsulation ingredients added in free form (Y). The standardised semi-dynamicin vitrodigestion method (INFOGEST) was employed to study the food digestion. The structure was analysed by confocal laser scanning microscopy and particle size distribution. Protein and lipid digestion were monitored by cumulated protein/free NH2 release and cumulated free fatty acids release, respectively. Stable microcapsules were observed during gastric digestion, but there was no significant difference in protein release/hydrolysis among samples until 55 min of gastric digestion. Formulation Y showed less protein release after 74 min (40.46 %) due to the free SPP being available and positively charged at pH 2-4, resulting in interactions with other constituents of the yoghurt, which delayed its release/hydrolysis. The total release of protein and free NH2 by the end of intestinal digestions ranged between 46.56-61.15 % and 0.83-1.57 µmol/g protein, respectively. A higher release of free fatty acids from formulation Y occurred at the end of intestinal digestion, implying that coacervates promoted the delayed release of encapsulated oil. In summary, incorporating protein-polysaccharides-based coacervates in yoghurt enabled the delay of the digestion of encapsulated lipids but accelerated the digestion of protein, suggesting a promising approach for various food applications.

The type of gum arabic affects interactions with soluble pea protein in complex coacervation.

Complex coacervation is an encapsulation process involving two oppositely charged biopolymers. Since different compositions of gum arabic may affect its interaction with protein, we studied the complex coacervation of two types of gum arabic (GA) (Acacia senegal-GA1 and Acacia seyal-GA2) with soluble pea protein (SPP) through Zeta potential, turbidity, morphology, the secondary structure of SPP, UV/vis absorbance and thermodynamic parameters. The maximum formation of coacervates occurred at SPP:GA 3:1 (w/w) and pH 3.5-4.0 with changes in the secondary structure of SPP. GA1 combination resulted in higher binding constant, implying a stronger affinity between SPP and GA1. Entropy of 0.7 and 0.5 kJ/mol.K, and enthalpy of -151 and -95.5 kJ/mol were obtained for SPP:GA1 and SPP:GA2. The complex coacervation was spontaneous as proved by the negative values of the Gibbs free energy. GA1 resulted in stronger interactions with SPP, offering new alternatives for encapsulation of bioactive compounds.

Advances of plant-based structured food delivery systems on the in vitro digestibility of bioactive compounds.

Food researchers are currently showing a growing interest in in vitro digestibility studies due to their importance for obtaining food products with health benefits and ensuring a balanced nutrient intake. Various bioactive food compounds are sensitive to the digestion process, which results in a lower bioavailability in the gut. The main objective of structured food delivery systems is to promote the controlled release of these compounds at the desired time/place, in addition to protecting them during digestion processes. This review provides an overview of the influence of structured delivery systems on the in vitro digestive behavior. The main delivery systems are summarized, the pros and cons of different structures are outlined, and examples of several studies that optimized the use of these structured systems are provided. In addition, we have reviewed the use of plant-based systems, which have been of interest to food researchers and the food industry because of their health benefits, improved sustainability as well as being an alternative for vegetarian, vegan and consumers suffering from food allergies. In this context, the review provides new insights and comprehensive knowledge regarding the influence of plant-based structured systems on the digestibility of encapsulated compounds and proteins/polysaccharides used in the encapsulation process.

Influence of heated, unheated whey protein isolate and its combination with modified starch on improvement of encapsulated pomegranate seed oil oxidative stability.

This study aimed at encapsulating pomegranate seed oil (PSO) by emulsification followed by spray drying using whey protein isolate (WPI) in its natural form, heated (Pickering), and combined with modified starch (WPI:Capsul®) as emulsifiers/wall materials. Emulsions were stable under different stress conditions. Pickering emulsions presented bigger droplet size (6.49-9.98 µm) when compared to WPI (1.88-4.62 µm) and WPI:Capsul® emulsions (1.68-5.62 µm). Sixteen fatty acids were identified in PSO. WPI treatment was considered the best formulation since it presented the highest fatty acid retention (68.51, 65.47, 47.27, 53.68, 52.95, and 52.28% for linoleic, oleic, punicic, α-eleostearic, catalpic, and ß-eleostearic acids after 30 days-storage, respectively) and protected the oil against volatile compound formation (heptanal, (E,E)-2,4-heptadienal, (Z)-2-heptenal, octanal, pentanal, (E)-2-hexenal, (E)-2-octenal, nonanal, (E)-2-decenal, and (E,E)-2,4-octadienal), which did not occur with free PSO. Overall, encapsulation protected PSO against oxidation over time, which may allow the development of new functional foods.

Microencapsulation of lactase by W/O/W emulsion followed by complex coacervation: Effects of enzyme source, addition of potassium and core to shell ratio on encapsulation efficiency, stability and kinetics of release.

This study evaluated the technological viability of the formation of lactase microcapsules by coacervation (gelatin/gum arabic) containing potassium ions (cofactor). The impacts of the encapsulation and the cofactor on the enzyme properties obtained from Aspergillus oryzae and Kluyveromyces lactis were evaluated as a function of different pH values, temperatures, and storage times. The best microcapsules formed by coacervation showed good functional properties, such as low water activity (≤ 0.4) and particle size (≤ 93.52 µm), as well as high encapsulation efficiency (≥ 98.67%). The potassium ions were capable of reducing the flexibility of the polypeptide backbone, thereby increasing the stability of the enzyme. The microcapsules were also capable of increasing the stability of the enzyme under unfavorable pH values, high temperatures and during storage. An in vitro experiment showed that microcapsules were effective in the retention of about 90% of the enzyme in simulated gastric fluid, but as much as 95% of the enzyme can be released from the capsules in simulated intestinal fluid. The released enzyme retained 83% and 66% of the total enzymatic activity for the capsules produced with lactase from Kluyveromyces lactis and A. oryzae, respectively. These results are promising and demonstrated that these microcapsules are a promising technology to protect and deliver bioactive proteins during storage and delivery in the GI tract.

Echium oil with oxidative stability increased by emulsion preparation in the presence of the phenolic compound sinapic acid followed by dehydration by spray and freeze drying processes.

Echium oil is rich in omega-3, however, is unstable. The objective of this work was the co-encapsulation of echium oil and sinapic acid (SA) by emulsification using Arabic gum as emulsifier/carrier, followed by spray or freeze-drying. Eight treatments (S0, S200, S600 and S1000: particles spray dried with different concentrations of SA; L0, L200, L600 and L1000: particles freeze dried with different concentrations of SA) were analyzed in relation to microscopy, water activity (Aw), hygroscopicity, moisture, solubility, particle size, X-ray diffraction, thermogravimetry and accelerated oxidation. Particles of rounded shape and undefined form were obtained by spray and freeze-drying, besides ideal physicochemical properties for application (values from 0.091 to 0.365, 3.22 to 4.89%, 57 to 68% and 2.32 to 12.42 µm for Aw, moisture, solubility and particle size, respectively). All treatments protected the oil against oxidation, obtaining induction time of 5.31 h for oil and from 7.88 to 12.94 h for treatments. The better protection to oil was obtained with it emulsified and freeze-dried (L600); the encapsulation increased oxidative stability of the oil, besides facilitating its application over the fact the material is in powder form.

Water-in-oil-in-water emulsion obtained by glass microfluidic device for protection and heat-triggered release of natural pigments.

Anthocyanins and norbixin are natural pigments used in food; however, they are unstable. The aim of this study was to evaluate the microencapsulation technique to protect these pigments. Elderberry extract (source of anthocyanins) and norbixin were encapsulated using a microfluidic device with palm oil as middle phase in a water-in-oil-in-water emulsion. The formulations were characterized for morphology, particle size, encapsulation efficiency, zeta potential, color release under heating, Fourier transform infrared spectrophotometry, and color stability under different conditions. Spherical, mononucleated microcapsules, with particle size of 187-190 µm (elderberry) and 164-184 µm (norbixin), and with encapsulation efficiencies values of 47.80-54.87% (elderberry) and 49.18-74.73% (norbixin) were obtained. The formulations showed high color retention, with the encapsulated elderberry extract stored at pH 3.0 being the most stable. This study shows that the microencapsulation of these pigments using a microfluidic device provided protection, and represents a new method for anthocyanins and norbixin delivery in foods.

Enhancing stability of echium seed oil and beta-sitosterol by their coencapsulation by complex coacervation using different combinations of wall materials and crosslinkers.

Intake of omega-3 fatty acids and phytosterols aids in the reduction of cholesterol and serum triglycerides. However, both fatty acids and phytosterols are susceptible to oxidation. This work coencapsulated echium oil (source of stearidonic and alpha-linolenic fatty acids) and beta-sitosterol (phytosterol) by complex coacervation using different combinations of wall materials, and sinapic acid (SA) and transglutaminase as crosslinkers. High encapsulation yields were obtained (29-93% for SA; 68-100% for the mixture of oil and phytosterols) and retention of 49-99% and 16% for encapsulated and free SA, at 30 days-storage. Treatment with gelatin-arabic gum and 0.075 g SA/g gelatin showed the best results: 0.07 mg MDA/g capsule, and retention of 96, 90 and 74% for alpha-linolenic, stearidonic acid and beta-sitosterol at 30 days of storage, respectively. Thus, coencapsulation of echium oil and phytosterol using SA as the crosslinker was possible, obtaining effective vehicles for protection and application of these compounds in foods.

Optimization of microcapsules shell structure to preserve labile compounds: A comparison between microfluidics and conventional homogenization method.

A new technique is presented to optimize the formulation of microcapsules loaded with labile compounds. Fish oil was loaded into the microcapsule core and protected with a shell composed of whey protein microgel/beet pectin complexes. The microcapsules were formed using two different methods: microfluidics and homogenization. The microcapsules were further classified into three sub-groups. The first group was the microcapsules cross-linked with laccase (MCL), the second group was the microcapsules cross-linked with divalent cationic CaCl2 salt (MCS), and the third group consisted of control microcapsules (CM), with no cross-linking. The microfluidics method enabled tracking of the effect of the shell cross-linking ability of laccase, or CaCl2, on microcapsules. It was demonstrated that MCL obtained by microfluidics are more physicochemically stable than those produced via a homogenizer. The effect of cross-linking agents on the microcapsules were more significant when the microcapsules were produced by microfluidics.

Development of functional yogurt containing free and encapsulated echium oil, phytosterol and sinapic acid.

The consumption of omega-3 fatty acids and phytosterol promotes the reduction of cholesterol and triacylglycerol levels. However, such compounds are susceptible to oxidation, which hampers their application. The objective of this work was to coencapsulate echium oil, phytosterols and sinapic acid (crosslinker/antioxidant), and incorporate the obtained microcapsules into yogurt. The microcapsules were evaluated for particle size, accelerated oxidation by Rancimat, and simulation of gastric/intestinal release. The yogurts were assessed for morphology, pH, titratable acidity, color, rheology and sensory analysis. The microcapsules (13-42µm) promoted protection against oil oxidation (induction time of 54.96h). The yogurt containing microcapsules, presented a pH range from 3.89 to 4.17 and titratable acidity range from 0.798 to 0.826%, with good sensorial acceptance. It was possible to apply the microcapsules in yogurt, without compromising the rheological properties and physicochemical stability of the product.

Improving oxidative stability of echium oil emulsions fabricated by Microfluidics: Effect of ionic gelation and phenolic compounds.

Echium oil is rich in omega-3 fatty acids, which are important because of their benefits to human health; it is, however, unstable. The objective of this work was the coencapsulation of echium oil and quercetin or sinapic acid by microfluidic and ionic gelation techniques. The treatments were analyzed utilizing optical and scanning electron microscopy, encapsulation yield, particle size, thermogravimetry, Fourier transform infrared spectroscopy, stability under stress conditions, and oil oxidative/phenolic compound stability for 30days at 40°C. High encapsulation yield values were obtained (91-97% and 77-90% for the phenolic compounds and oil) and the encapsulated oil was almost seven times more stable than the non-encapsulated oil (0.34 vs 2.42mgMDA/kg oil for encapsulated and non-encapsulated oil, respectively). Encapsulation was shown to promote oxidative stability, allowing new vehicles for the application of these compounds in food without the use of solvents and high temperature.

Effect of different polysaccharides and crosslinkers on echium oil microcapsules.

Microencapsulation by complex coacervation using gelatin and arabic gum (AG) as wall materials and transglutaminase for crosslinking is commonly used. However, AG is only produced in a few countries and transglutaminase is expensive. This work aimed to evaluate the encapsulation of echium oil by complex coacervation using gelatin and cashew gum (CG) as wall materials and sinapic acid (S) as crosslinker. Treatments were analyzed in relation to morphology, particle size, circularity, accelerated oxidation and submitted to different stress conditions. Rounded microcapsules were obtained for treatments with AG (45.45µm) and microcapsules of undefined format were obtained for treatments with CG (22.06µm). The S incorporation for 12h improved the oil stability by three fold compared to oil encapsulated without crosslinkers. Treatments with CG and S were resistant to different stress conditions similar to treatments with AG and transglutaminase, making this an alternative for delivery/application of compounds in food products.

Protection of echium oil by microencapsulation with phenolic compounds.

The consumption of omega-3 enables the reduction of cardiovascular disease risk; however they are unstable. The aim of this work was to encapsulate echium oil (Echium plantagineum L.), a rich source of omega-3 fatty acids, with phenolic compounds (sinapic acid and rutin) by double emulsion followed by complex coacervation or by complex coacervation with sinapic acid in the capsule wall. Analyses of morphology, particle size, circularity, water activity, moisture, Fourier transform infrared spectroscopy, thermogravimetry, process yield, accelerated oxidation and identification and quantification of fatty acids present in the encapsulated oil were performed. Samples presented values of encapsulation process yield of phenolics and oil in the range of 39-80% and 73-99%, respectively. Moreover, all samples protected the oil against oxidation, obtaining induction time (accelerated oxidation) of 5h for pure oil and values in the range from 10 to 18h for samples. Thus, better protection to the oil was possible with sinapic acid applied in the capsule wall, which enhances its protection against lipid oxidation.

Fabrication of solid lipid microcapsules containing ascorbic acid using a microfluidic technique.

The importance of ascorbic acid (AA) in the human diet has motivated food researchers to develop AA-fortified food products. However, this compound is very unstable. The aim of this work was to produce solid lipid microcapsules (SLMs) loaded with AA using microfluidic technology. The morphology of the SLMs was analysed by optical, scanning electron and confocal microscopy. We determined the encapsulation efficiency, particle size and stability of the encapsulated material. Two different means of enhancing the encapsulation efficiency and stability of AA were demonstrated: a pore blocking method and a micromolecule-chelating agent within the core. The results indicated the enormous potential of the designed vehicle to prevent AA degradation in a food product; additionally, this vehicle could mask the acidic taste of AA.