Influence of Emulsification Technique and Wall Composition on Physicochemical Properties and Oxidative Stability of Fish Oil Microcapsules Produced by Spray Drying

Encapsulation of fish oil is an effective way to protect it against oxidation and masking its fishy odor. One of the possible ways to produce fish oil microcapsules is to produce an oil-in-water (O/W) emulsion followed by spray drying. This study compares the production of the O/W emulsion by mechanical homogenization (rotor–stator) with membrane emulsification and examines the effect of the type and amount of wall material added before drying. The membrane emulsification process selected for the emulsion production is premix membrane emulsification (ME), which consists of the production of a coarse emulsion by mechanical means followed by droplet breakup when the coarse emulsion is forced through a membrane. The emulsions produced had an oil load of 10 and 20 % and were stabilized using whey protein (isolate and hydrolyzate at 1 or 10 %) and sodium caseinate with concentrations of 2 and 10 %. Regarding the material used to build the microcapsule wall, whey protein, maltodextrin, or combinations of them were used at three different oil/wall ratios (1:1, 1:2, 1:3). The results clearly show that premix ME is a suitable technology for producing O/W emulsions stabilized with proteins, which have a smaller droplet size and are more monodisperse than those produced by rotor–stator emulsification. However, protein concentrations of 10 % are required to reduce the droplet size down to 2–3 μm. Small and monodisperse emulsions have been found to produce microcapsules with lower surface oil content, which increases oil encapsulation efficiency and presents lower levels of oxidation during storage at 30 °C. Of all the possible combinations studied, the one with the highest oil encapsulation efficiency is the production of a 20 % O/W emulsion stabilized with 10 % sodium caseinate followed by the addition of 50 % maltodextrin and drying.     

Fish oil microencapsulation as influenced by spray dryer operational variables

The effects of spray‐drying air temperature, aspirator rate (drying air mass flow rate), peristaltic pump rate (feed mass flow rate) and spraying air mass flow rate on microencapsulation properties of fish oil including moisture content, particle size, bulk density, encapsulation efficiency and peroxide were investigated. The process was carried out on a mini spray dryer, and skim milk powder was used as the encapsulating wall material. Results indicated that increasing inlet air temperature increased the particle size, encapsulation efficiency and peroxide value but decreased the bulk density and moisture content of product. Increasing aspirator rate resulted in increased particle size and peroxide value but decreased the moisture content and bulk density. Increase in feed mass flow rate increased the moisture content, particle size, bulk density and peroxide value but decreased the encapsulation efficiency of microcapsules. The encapsulation efficiency and bulk density increased with the increasing aspirator rate but moisture content, particle size and peroxide value decreased.     

Impact of Wall Materials on Physicochemical Properties of Microencapsulated Fish Oil by Spray Drying

The aim of the present study was to investigate the effect of wall materials composition on physicochemical characteristics of fish oil microcapsules produced by spray drying (180 °C). Four different combination of coating materials (fish gelatin, chitosan, combination of gelatin and chitosan, and a mixture of microbial transglutaminase (MTGase) with maltodextrin) were applied to two different fish oils to produce 40 % solid emulsions. Scanning electron microscopy and extraction of surface and encapsulated oils revealed that fish gelatin provided the highest preserving effect on the covering fish oil. Meantime, addition of MTGase to gelatin could also increase this ability and reveled less surface oil than chitosan treatment (2.63 and 2.80 % versus 4.66 and 5.23 %, respectively; P?<?0.05). Mixture of gelatin and maltodextrin with MTGase as wall material led to the highest encapsulation efficiency, being selected as the best microencapsulation condition; meantime, application of chitosan with maltodextrin provided the worse encapsulation efficiency (P?<?0.05). All indices of powders (encapsulation efficiency, surface morphology, and particle size) showed that powders prepared from gelatin and gelatin with MTGase increased the encapsulation efficiency and would increase the stability of microcapsule powders.     

Impact of Milk Protein Type on the Viability and Storage Stability of Microencapsulated Lactobacillus acidophilus NCIMB 701748 Using Spray Drying

Three different milk proteins — skim milk powder (SMP), sodium caseinate (SC) and whey protein concentrate (WPC) — were tested for their ability to stabilize microencapsulated L. acidophilus produced using spray drying. Maltodextrin (MD) was used as the primary wall material in all samples, milk protein as the secondary wall material (7:3 MD/milk protein ratio) and the simple sugars, d-glucose and trehalose were used as tertiary wall materials (8:2:2 MD/protein/sugar ratio) combinations of all wall materials were tested for their ability to enhance the microbial and techno-functional stability of microencapsulated powders. Of the optional secondary wall materials, WPC improved L. acidophilus viability, up to 70 % during drying; SMP enhanced stability by up to 59 % and SC up to 6 %. Lactose and whey protein content enhanced thermoprotection; this is possibly due to their ability to depress the glass transition and melting temperatures and to release antioxidants. The resultant L. acidophilus powders were stored for 90 days at 4 °C, 25 °C and 35 °C and the loss of viability calculated. The highest survival rates were obtained at 4 °C, inactivation rates for storage were dependent on the carrier wall material and the SMP/d-glucose powders had the lowest inactivation rates (0.013 day^?1) whilst the highest was observed for the control containing only MD (0.041 day^?1) and the SC-based system (0.030 day^?1). Further increase in storage temperature (25 °C and 35 °C) was accompanied by increase of the inactivation rates of L. acidophilus that followed Arrhenius kinetics. In general, SMP-based formulations exhibited the highest temperature dependency whilst WPC the lowest. d-Glucose addition improved the storage stability of the probiotic powders although it was accompanied by an increase of the residual moisture, water activity and hygroscopicity, and a reduction of the glass transition temperature in the tested systems.     

Impact of chitosan and oregano extract on the physicochemical properties of microencapsulated fish oil stored at different temperature

Fish oil is an excellent source of omega-3 fatty acids and is easily susceptible to oxidation. Microencapsulation is a commonly employed technique to protect fish oil against oxidation. In the present study, the potential of chitosan in combination with bovine gelatin and maltodextrin as wall material for microencapsulation of fish oil by spray drying was evaluated. To improve the oxidative stability of the fish oil microencapsulates, oregano (Origanum vulgare L) extract was added at 0.50 g/100 g of emulsion. The spray-dried powder showed a moisture content of 2.8 – 3.2 g/100 g of spray-dried powder. The powder contained spherical microparticles with different sizes as indicated by scanning electron microscope images. Encapsulation efficiency of microencapsulates ranged between 68.94% and 81.88%. Differential scanning calorimetry and Fourier-transformed infrared spectroscopy analysis of microencapsulates revealed the possible structural stabilization of core and wall material. The oxidative stability of fish oil microencapsulates were monitored under three different temperature (60°C, 28 ± 2°C, and 4°C). Incorporation of oregano extract minimized the generation of secondary and tertiary oxidation products as indicated by lower peroxide value and thiobarbituric acid reactive substance values compared to control. Overall, the results suggested that combination of chitosan along with bovine gelatin and maltodextrin as wall material improved the surface morphology of the microparticle and encapsulation efficiency, whereas incorporation of oregano extract in fish oil before spray drying enhanced the oxidative stability during storage.     

Maillard Reaction Products as Encapsulants for Fish Oil Powders

The use of Maillard reaction products for encapsulation of fish oil was investigated. Fish oil was emulsified with heated aqueous mixtures comprising a protein source (Na caseinate, whey protein isolate, soy protein isolate, or skim milk powder) and carbohydrates (glucose, dried glucose syrup, oligosaccharide) and spray‐dried for the production of 50% oil powders. The extent of the Maillard reaction was monitored using L*, a*, b* values and absorbance at 465 nm. Encapsulation efficiency was gauged by measurement of solvent‐extractable fat and the oxidative stability of the fish oil powder, which was determined by assessment of headspace propanal after storage of powders at 35 °C for 4 wk. Increasing the heat treatment (60 °C to 100 °C for 30 to 90 min) of sodium caseinate‐glucose‐glucose syrup mixtures increased Maillard browning but did not change their encapsulation efficiency. The encapsulation efficiency of all heated sodium caseinate‐glucose‐glucose syrup mixtures was high, as indicated by the low solvent‐extractable fat in powder (<2% powder, w/w). However, increasing the severity of the heat treatment of the sodium caseinate‐glucose‐glucose syrup mixtures reduced the susceptibility of the fish oil powder to oxidation. The increased protection afforded to fish oil in powders by increasing the temperature‐time treatment of protein‐carbohydrate mixtures before emulsification and drying was observed irrespective of the protein (sodium caseinate, whey protein isolate, soy protein isolate, or skim milk powder) and carbohydrate (glucose, glucose/dried glucose syrup, or oligosaccharide/dried glucose syrup) sources used in the formulation. Maillard reaction products produced by heat treatment of aqueous protein‐carbohydrate mixtures were effective for protecting microencapsulated fish oil and other oils (evening primrose oil, milk fat) from oxidation.     

Compression Strength of Dairy Gels and Microstructural Interpretation

Contour plots were developed for the compression stress (at 20% deformation) of single-component, mixed and filled protein gels. Samples were made by heating and acidification from skim milk powder, SMP (0–20% TS), whey protein isolate, WPI (0–10% TS), and recombined cream, within pH 3.6–3.9, 4.6–4.8 and 5.1–5.3. At higher pH, WPI gels were stronger than SMP gels. WPI had a reinforcing effect on SMP gels, while small additions of SMP to WPI gels resulted in weaker mixed gels. Filled gels containing cream had higher compression strengths than mixed gels. Micrographs showed linking of casein chains by WPI strands in mixed gels and compatibility of fat globules with casein micelles in the protein network of filled gels.     

Microencapsulation of walnut oil by spray drying: Effects of wall material and drying conditions on physicochemical properties of microcapsules

In this study, the effects of wall material formula and spray drying conditions on physicochemical properties of walnut oil microcapsules were investigated. Three different wall materials including skim milk powder (SMP), SMP + Tween 80, and SMP + maltodextrin were used for emulsion preparation. The prepared emulsions were analyzed for droplet size and stability. The emulsions were then dried in a pilot-scale spray dryer equipped with a two-fluid nozzle at different inlet drying air temperatures and feed atomization pressures in order to determine the optimal drying conditions for maximizing the microencapsulation efficiency. The microencapsulation efficiency, particle size distribution, sphericity, moisture content, bulk density, and morphology of produced microcapsules were also measured experimentally. In addition, the microcapsules with the highest microencapsulation efficiency obtained from each wall material were subjected to surface coverage of oil test using electron spectroscopy for chemical analysis (ESCA) after 60 days of storage at room temperature. The emulsion prepared using SMP and Tween 80 combination as wall material resulted in the highest microencapsulation efficiency (91.01%) at drying air temperature of 180 °C and feed atomization pressure of 3 bar. The lowest surface coverage of oil was also observed for microcapsules covered by SMP and Tween 80 combination. Scanning electron microscopy (SEM) observations showed almost no cracks or fissures on the surface of microcapsules produced using SMP and Tween 80 combination at the optimal drying condition.Industrial relevanceWalnut oil contains highly valuable constituents such as essential fatty acids, tocopherols, and phytosterols. However, a direct application of this functional oil in processed foods is problematic due to its low solubility and susceptibility to oxidation. These issues could be greatly overcome by using microencapsulation technology. Nowadays, this technology has received an increasing attention in food and pharmaceutical industries due to its unique features in protecting the functionality of ingredients. Spray drying technology is one of the most frequently used techniques for this aim. However, comprehensive studies need to be carried out in order to determine suitable operational conditions of spray drying system for improving physicochemical properties of finished powder.     

The Influence of Drying Process Conditions on the Physical Properties,Bioactive Compounds and Stability of Encapsulated Pumpkin Seed Oil

In this study, the influence of encapsulation process conditions on the physical properties and chemical composition of encapsulated pumpkin seed oil was investigated. Four variants of encapsulated oil were prepared: spray-dried non-homogenized emulsions at the inlet temperatures of 180 and 130 °C, spray-dried homogenized emulsion at the inlet temperature of 130 °C, and freeze-dried homogenized emulsion. The emulsion was prepared by mixing 10.6% oil with 19.8% wall materials (15.9% maltodextrin + 0.5% guar gum + 3.9% whey protein concentrate) and 69.6% distilled water. The quality of encapsulated pumpkin seed oil was evaluated by encapsulation efficiency, surface oil, total oil and moisture contents, flowing properties, color, and size. Additionally, fatty acid composition, pigment characteristics, and the content of bioactive compounds (tocopherols, squalene, and sterols) were determined. Changes of these components after the encapsulation process in comparison to the control pumpkin seed oil were considered as stability parameters. The highest encapsulation efficiency was obtained by spray-drying at the inlet temperature of 130 °C. Generally, the spray-drying process had a positive effect upon the physical parameters of encapsulated pumpkin seed oil but results were dependent on process conditions. The higher inlet temperature generated more surface oil, but capsules obtained at the lower temperature were greater in size and more deformed. Although freeze-drying proceeded at a very low temperature, the powder obtained with this technique was characterized by the highest bioactive compound losses (with the exception of sterols) and the lowest stability. The homogenization process applied before spray-drying affected greater polyunsaturated fatty acid, squalene, and pigment degradation. In conclusion, results of the study showed that the spray-drying non-homogenized emulsion was a more recommendable technique for the encapsulation of pumpkin seed oil because of smaller changes of native compounds and better oxidative stability.     

Short communication: Annatto in Cheddar cheese-derived whey protein concentrate is primarily associated with milk fat globule membrane

The yellow color of Cheddar cheese whey arises from a residual amount of annatto that partitions into the whey during Cheddar cheese manufacture. Bleaching of the color using hydrogen peroxide or benzoyl peroxide is often a prerequisite to produce an acceptable neutral-colored whey protein concentrate and isolate. However, the use of these strong oxidizing agents often generates off-flavors as a result of lipid oxidation and results in loss of nutritive value due to protein oxidation. The objective of this study was to determine the extent of partitioning of annatto between protein, milk fat globule membrane (MFGM), and aqueous (serum) phases of cheese whey so that a simple method can be developed to remove annatto from cheese whey. The MFGM was separated from Cheddar cheese whey using a recently developed novel method. Quantitative analysis of the distribution of annatto in the fat-free whey protein isolate (WPI), the MFGM fractions, and the serum phase revealed that annatto was not bound to the protein fraction but was mostly distributed between the serum phase and the MFGM fraction. The results showed that a colorless WPI or whey protein concentrate could be produced from Cheddar cheese whey by separation of MFGM from the whey, followed by diafiltration. This approach will negate the need for using bleaching agents.     

蛋白质强化对搅拌型酸奶品质特性的影响

为了研究蛋白质强化对搅拌型酸奶品质特性的影响,以脱脂奶粉(SMP)和乳清浓缩蛋白-80(WPC-80)作为蛋白源,研究了强化不同种类及不同含量(2.7%、3.1%、3.5%、3.9%)的蛋白质强化对搅拌型酸奶感官品质、黏度和持水性的影响。结果表明:用SMP和WPC-80强化原料乳的蛋白质均可提高搅拌型酸奶的感官品质、黏度和持水性;比较同种蛋白源、不同蛋白质强化水平制得的搅拌型酸奶,其组织状态变化明显,风味稍有变化,色泽保持不变;酸奶的黏度和持水性都随蛋白质水平的上升而显著提高。SMP强化蛋白质含量至2.7%时,酸奶的感官品质最好;WPC-80含量则在3.5%时,酸奶的感官品质最好。同一蛋白质水平、不同强化蛋白相比较,WPC-80强化酸奶比SMP有更好的感官品质和更高的持水性,而SMP强化则得到更高的黏度值;从感官评定的黏稠度得分和测得的黏度值对比得出,搅拌型酸奶的黏度并不是越高越好,最佳黏度值在537～712mPa.s之间。实验中搅拌型酸奶的最佳蛋白强化配方为WPC-80强化蛋白质含量3.5%。     

Encapsulation of eugenol using Maillard-type conjugates to form transparent and heat stable nanoscale dispersions

Maillard-type protein-carbohydrate conjugates are known for their excellent emulsifying properties and have been used to encapsulate volatile oils and flavor compounds. In the present study, eugenol was used as a model compound for encapsulation in conjugates of whey protein isolate (WPI) and maltodextrins (MD) made using different WPI:MD mass ratios and MD chain lengths. The encapsulation involved two steps, emulsifying an oil phase of eugenol dissolved in hexane into an aqueous phase with dissolved conjugates and spray drying the emulsion. Mass yield up to 82.7 g/100 g and encapsulation efficiency as high as 35.7 g/100 g eugenol were observed. After hydrating spray-dried powders, several samples with an eugenol content above its solubility limit demonstrated transparent dispersions at pH 3.0 and 7.0 after heating at 80 °C for 15 min, corresponding to mean diameters smaller than ca. 100 nm. One treatment also showed transparent dispersions after heating at pH 5.0, which is near the isoelectric point of whey proteins, in contrast to gel formation for a control prepared with a mixture of non-conjugated WPI and MD. The present study demonstrates potential to produce food grade nanoscale systems for delivering lipophilic bioactives in functional beverages, without adversely affecting their visual appearance.     

Proposing Novel Encapsulating Matrices for Spray-Dried Ginger Essential Oil from the Whey Protein Isolate-Inulin/Maltodextrin Blends

The aim of this study was to evaluate the effects of the blending of whey protein isolate (WPI) with maltodextrin (MD) and inulin (IN) biopolymers as encapsulating matrices for spray-dried ginger essential oil. Encapsulation was performed by ultrasound-assisted emulsification and using spray drying, and the stability parameters of the emulsion (with or without ultrasound-assisted) were evaluated. The influence of these different wall material systems was investigated based on various functional properties of microparticles such as stability of the emulsion, encapsulation efficiency, reconstitution properties, chemical profile, microparticle stability, morphology, particle size distribution, and crystallinity. Higher viscosity values were obtained for the emulsions prepared with WPI and IN which had the apparent viscosity increased by the ultrasound-assisted emulsification process. Creaming index values indicated that ultrasound-assisted emulsions had higher stability. The composition of the wall materials did not affect the solubility and the moisture content of the particles. The wettability property of the powders was improved by the addition of IN. The lowest level of water adsorption under conditions of high relative humidity was also observed in microparticles containing IN. The partial replacement of WPI by MD significantly affected the efficiency of encapsulation. Moreover, MD led to high thermal microparticle stability. Larger particles were observed in the powders prepared with WPI. The powders obtained from WPI, WPI:IN, and WPI:MD treatments exhibited amorphous structures and did not have any cracks on the surface. The findings of this study indicate that IN and MD together with WPI proved to be good alternative secondary wall materials for spray-dried ginger oil.     

Spray-dried conjugated linoleic acid encapsulated with Maillard reaction products of whey proteins and maltodextrin

Encapsulation performance of Maillard reaction products (MRPs) produced by whey proteins and maltodextrin were examined for microencapsulation of conjugated linoleic acid (CLA) using spray-drying. CLA was encapsulated using 3 different wall materials containing a single constituent such as whey protein concentrate (WPC), whey protein isolate (WPI), and maltodextrin (MD), and 4 different MRPs. For the development of MRPs, ratios of WPC to MD were 1:2 and 1:3, whereas those of WPI to MD were 1:5 and 1:10. CLA and wall material were mixed and homogenized, and then spraydried. The physical properties of encapsulated CLA powders were characterized by particle size and morphology, ζ-potential, flowability, solubility, and dispersibility. The CLA powders coated with WPI-based MRPs have better encapsulation efficiency, water solubility, and smaller particle size than those coated with WPI, WPC, or MD alone. These encapsulated CLA powders have a number of possible utilities as ingredients in a variety of foods.     

Study of Different Wall Matrix Biopolymers on the Properties of Spray-Dried Pequi Oil and on the Stability of Bioactive Compounds

This work aimed to evaluate the effect of the partial replacement of whey protein isolate (WPI), by maltodextrin (MD) and by inulin (IN), on the characteristics of spray-dried pequi oil and on the degradation of its bioactive compounds. Three treatments, WPI, WPI/MD (1:1), and WPI/IN (1:1), were carried out, and the characteristics of the emulsions and microparticles were evaluated. In addition, thermal analysis, X-ray, and scanning electron microscopy of microparticles were carried out. It was found that the solubility of the encapsulations was affected by the composition of the wall material and reached higher value (88.26%) when IN was applied. The encapsulation efficiency (74.49%) was lower with IN. The particles presented amorphous characteristics, and the treatments WPI and WPI/IN exhibited smoother and spherical morphology. WPI and WPI/MD showed greater thermal stability and also better protection of the antioxidative capacity of the oil through the β-carotene bleaching assay. The WPI system showed better protection of β-carotene, δ-carotene, and lycopene, compared to the bulk oil, while WPI/MD protected better the γ-carotene and WPI/IN showed better protection of α-carotene.     

Functionality of spray-dried strawberry powder: effects of whey protein isolate and maltodextrin

The effectiveness of two drying agents, namely whey protein isolate (WPI) and maltodextrin (MD), was evaluated during spray-drying of strawberry puree. With the increase of WPI substitution in the feed material, the surface tension of strawberry puree decreased, and powder recovery increased. Powder recovery (R_p) increased from 39.2 ± 2.3% (S:MD:WPI = 60:40:0) to 56.5 ± 2.8% when MD was replaced by WPI (S:MD:WPI = 60:39:1). Surface morphology of powders showed that the addition of WPI resulted in shrunken particle surface, which gave rise to smaller D_B and particle size. The particles were not spherical, and even with the addition of 0.5% WPI, the particle morphology was altered. The surface shrinkage of strawberry powder increased with increase in WPI from 0.5% to 10%. The production efficiency of strawberry powder could be greatly improved when MD was replaced by 1% WPI.     

Interactions between food components in ice cream. Part 1: unfrozen emulsions

Ice cream was manufactured on a pilot plant and the structure of the emulsion was estimated in terms of droplet size distribution and protein composition of the aqueous phase after homogenization (two stages: 19 MPa + 3 MPa, 70°C) and after ageing ( 18 h, 4°C). Four different factors were studied: the nature of the milk protein [skim milk powder (SMP), skim milk replacer (SMR) or whey protein concentrate ( WPC) ], the nature of the emulsifier (saturated monoglycerides or Sugin Fl50, which is apolysorbate 80-based emulsifier) and its concentration (0.17–0.67% w/w for Sugin F150; 0.20–0.54% wlw for saturated monoglycerides), and the amount of butter oil (8–12% wlw). Freshly homogenized mixes containing either SMP or an SMR were stable during the ageing stage, irrespective of the nature and the concentration of the emulsifier. WPC-based mixes, however, were destabilized after homogenization: this destabilization was found to be flocculation only, which shows that whey proteins are efficient against coalescence. The quantity of adsorbed protein per surface unit was systematically higher for SMP mix than for both SMR and WPC. After the ageing stage, the structure of the mixes containing monoglycerides or WPC + polysorbate 80 remained unchanged. However, polysorbate 80 used in combination with both SMP and SMR led to a destabilization of the mix during the ageing stage: this destabilization was found to depend upon the mass/surface ratio of polysorbate 80 to butteroil.     

An integrated process for utilization of pomegranate wastes — Seeds

In this work, a new method for pomegranate seeds application was developed based on the ultrasound-assisted extraction of seed oil and its subsequent encapsulation by spray drying. Extraction temperature, solvent/solid ratio, amplitude level, and pulse duration/pulse interval ratio were the factors investigated with respect to extraction yield. Ultrasound was sound to increase extraction yield, but mainly to shorten the treatment time by over 12 times. Different materials were used as encapsulating agents. Ratio of core to wall material, inlet air temperature, drying air flow rate, and feed solids concentration were the factors investigated with respect to encapsulation efficiency. The resulting microcapsules were evaluated in terms of moisture content, bulk density, and rehydration ability. The optimum operating conditions were found to be: wall material, maltodextrin/Tween 80; ratio of core to wall material, 0.23; inlet air temperature, 150 °C; drying air flow rate, 22.8 m³/h; feed solids concentration, 30% (w/w).Industrial relevancePomegranate seeds, a by-product of pomegranate juice and concentrate industries, present a wide range of pharmaceutical and nutraceutical properties. Therefore, the seeds could have more beneficial applications in food industries instead of being used as animal feed or in commercial cosmetic products. In this work, a new method for pomegranate seeds application was developed based on the ultrasound-assisted extraction of seed oil and its subsequent encapsulation by spray drying.     

Development and Characterization of Phytosterol-Enriched Oil Microcapsules for Foodstuff Application

Phytosterols are lipophilic compounds contained in plants and have several biological activities. The use of phytosterols in food fortification is hampered due to their high melting temperature, chalky taste, and low solubility in an aqueous system. Also, phytosterols are easily oxidized and are poorly absorbed by the human body. Formulation engineering coupled with microencapsulation could be used to overcome these problems. The aim of this study was to investigate the feasibility of encapsulating soybean oil enriched with phytosterols by spray-drying using ternary mixtures of health-promoting ingredients, whey protein isolate (WPI), inulin, and chitosan as carrier agents. The effect of different formulations and spray-drying conditions on the microencapsules properties, encapsulation efficiency, surface oil content, and oxidation stability were studied. It was found that spherical WPI-inulin-chitosan phytosterol-enriched soybean oil microcapsules with an average size below 50 μm could be produced with good encapsulation efficiency (85%), acceptable level of surface oil (11%), and water activity (0.2–0.4) that meet industrial requirements. However, the microcapsules showed very low oxidation stability with peroxide values reaching 101.7 meq O₂/kg of oil just after production, and further investigations and optimization are required before any industrial application of this encapsulated system.     

Fish Oil Microcapsules from O/W Emulsions Produced by Premix Membrane Emulsification

Fish oil microcapsules were prepared by combining a low-energy emulsification method (premix membrane emulsification) with spray drying. Oil-in-water (O/W) emulsions were prepared using a two-step emulsification method that used a rotor–stator homogenizer followed by membrane emulsification. The influence of the emulsification method (mechanical stirring or membrane emulsification), the emulsification conditions (membrane and emulsifier type), and the amount of wall material on the physicochemical characteristics of the microcapsules was studied. The results show that the emulsification method and the type and amount of emulsifier and wall material affect the final amount of encapsulated oil. Microcapsules produced by membrane emulsification and stabilized with 2 % Tween-20 or 10 % whey protein presented the highest values (higher than 50 %) of oil encapsulation efficiency (OEE). It has been found that the OEE increases when decreasing the droplet size of the emulsions as well as with the increase of the amount of wall material employed during drying. Morphology analysis showed that the microcapsules obtained from O/W emulsions produced by premix membrane emulsification were rounder in shape, without visible cracks on the surface and no vacuoles on the inside. Oxidation stability tests performed on some selected samples indicate that the microcapsules with higher stability are the ones produced with a higher amount of wall material and have less surface oil.