THE USE OF WHEY PROTEINS AS COATING MATERIAL IN NANOENCAPSULATION AND MICROENCAPSULATION APPLICATIONS

__________________________________________ ABSTRACT Encapsulation technology has applications in various fields, including the food, agriculture, pharmaceutical, and cosmetic industries. In the food field, encapsulation is carried out using bioactive components such as flavor components, micronutrients, fatty acids, vitamins, enzymes, antioxidants, polyphenols, known as the core materials, and carbohydrates, gums, and proteins such as shell (coating) material. Among coating materials, whey proteins are commonly used in microencapsulation and nanoencapsulation applications. Whey proteins used as coating material protect food against external influences and increase the nutritional value of the food and the health functionality of the foods to which they are added. However, there are some limitations due to the low solubility of whey proteins in aqueous media. High hygroscopicity, likely to promote unpleasant taste. To overcome these, researchers are continuing optimization studies for technologies using these hydrolysates and isolates in different food matrices. The use of whey proteins as a capsule material for encapsulating food ingredients with micro/nanoencapsulation techniques is becoming increasingly common. This review is focused on the nanoencapsulation and microencapsulation techniques and the use of whey proteins as coating material for different substances in the food industry is evaluated.


INTRODUCTION
The encapsulation technique is a process of coating the core material (food ingredients or biologically active material) in solid or liquid form with a shell material in the polymer matrix.In other words, encapsulation is the retention of an active substance in a carrier substance (wall material).It is a rapidly expanding technology due to its wide application areas in the food, nutrition, pharmaceutical, agriculture, and cosmetic industries (EZHILARASI et al., 2013;FANGMEIER et al., 2019).The encapsulated material is called the core; whereas the encapsulating material is called a coating, shell, membrane, capsule, carrier material, matrix or, outer phase (DEVI et al., 2017;MURTHY et al., 2018).This technique is used for various purposes, such as increasing the stability of the coated components, protecting and facilitating their use, avoiding undesirable reactions, and providing a controlled release of active ingredients.(XU et al., 2017;CARVALHO et al., 2019).This technique also helps to reduce the interaction between environmental and core factors.It can prevent changes that can cause the loss of properties really important to the sensory, such as aroma, colour, or nutritional value (FANGMEIER et al., 2019).
The choice of wall materials in the encapsulation process is an important step in developing capsules because it determines the strength and stability of the obtained capsules.In food applications, milk proteins, natural biopolymers, natural gums, and starches must be compatible with the food and have safe properties used as wall materials (NORKAEW et al., 2019).
Whey protein is widely used in food applications because it contains essential amino acids valuable for nutritional physiology and other functional properties in the human body.Whey proteins are a mixture of α-lactalbumin and βlactoglobulin globular proteins.In addition to their nutritional properties, they have some other functional properties as coating material.For instance, whey proteins can trap hydrophobic compounds such as vitamin D3.Whey protein concentrates can be used as a wall material for encapsulation due to their surfactant properties and can form a protective coating around core materials due to hydrophobic interactions, as mentioned above (KHAN et al., 2019;LEKSHMI et al., 2019).
Using whey proteins in encapsulation applications in the food industry enables to increase the nutritional value and health functionality of the foods to which they are added.Consumers who value healthy eating habits consider whey proteins to have lower allergenicity and higher bioavailability so they can be consumed in their diet.This review focuses on the studies that use whey proteins as coating materials and supply information about the manufacturing processes with different technologies.
When choosing an encapsulation method for detailed application in the food industry, the required particle size must be determined first.And then, the parameters of the encapsulation material, its physical and chemical properties, active ingredient and carrier, cost, and production scale must be considered.

Spray Drying
Spray drying is one of the most economical, simple, and widely used techniques in food and medicine for encapsulating various substances such as probiotics, nutraceuticals, flavor compounds, enzymes, peptides, etc. Active ingredients (food flavors, oils, or drugs) and polymer coating material suitable for encapsulation dissolved in a solvent or the active ingredient suspended in the polymer solution.When the suspensions encounter hot air, the atomized droplets' solvent evaporates to obtain dry powder capsules.One of the most important factors limiting the application of spray drying is the selection of suitable shell materials for applying this technique.The important advantages of this method are the high production rate and the costbenefit ratio.If high temperatures are applied while using this technique, the biological effectiveness of the components may be impaired.Today, spray drying is considered one of the most preferred and low-cost techniques among other methods (KOÇ; SAKIN, 2010;XU et al., 2017;ZANONI et al., 2020).
The spray drying technique is widely used to prevent the chemical and/or microbiological deterioration of the products, ensure their microbiological stability, protect the products' specific properties, and reduce storage and transportation costs.At the same time, spray drying technology is the most widely used encapsulation technique due to its high drying performance.(GÖKMEN et al., 2012).

Spray Cooling
Spray cooling consists of an atomization source, particle formation chamber, and collection zone.The most important difference from spray drying is the particle formation area.In the particle formation zone, the particles are formed not by solvent evaporation, but by cooling and hardening the droplets (OXLEY, 2012).The core material is melted or dispersed in a molten carrier with spray cooling.The final preparation is fed through an atomizing nozzle and sprayed into a cooling chamber.Finally, the molten droplets in contact with the cooled air harden.Spray cooling can also be optimized by making changes such as changing the temperature of the supply line and cooling the air used in the operation.After this technique, particles are formed and the core material is evenly distributed (GAVORY et al., 2014;BAMPi et al., 2016).The spray-cooling encapsulation process has been reported for food ingredients, active pharmaceutical ingredients, and sweeteners (GIBBS et al., 1999).The spray cooling technique is well suited for encapsulating active pharmaceutical ingredients as it is a low-cost process; It is easy to scale up and does not need organic solvents (FAVARO-TRINDADE et al., 2021).
Spray cooling technique has advantages such as speed, performance, and relatively low cost.Elimination of solvents is not necessary, as its application does not require the use of organic solvents.It is also considered a reproducible physical process with easy _________________________________________________________________________________________________________________ ________________________________________________________________________________________________________________ Rev. Inst.Laticínios Cândido Tostes, Juiz de Fora, v. 78, n. 3, p. 102-121, jul/sep, 2023 particle size adjustments (ALBERTINI et al., 2004).

Extrusion
This technique is mainly applied for encapsulating living cells without other options.One of the 'gentle' approaches to encapsulation, the extrusion technique, is particularly recommended for probiotics or other microorganisms (BILUŠIĆ et al., 2021).The extrusion method is the oldest and most widely used in hydrocolloid encapsulation processing.With this technique, the bioactive materials are mixed with the encapsulating material to form capsules immediately in a solidification bath of the droplets (FANGMEIER et al., 2019;SANDOVAL-MOSQUEDA et al., 2019).Extrusion technology has assisted in producing extrudate with a small particle size that can be used in food applications.It provides many solutions to the problems encountered during the encapsulation of bioactive compounds.
Carbohydrates (Starch, Maltodextrins, Gum Arabic, Alginate, and Cyclodextrins) are used as wall material in extrusion technology.For flavor compounds, and other carbohydrates especially maltodextrins and cyclodextrins; Alginates (Sodium alginate) are widely used during the extrusion of encapsulation of probiotic bacteria (BAMIDELE; EMMAMBUX, 2020).The most important advantage of this technique is the absence of solvent use and the absence of excessive heat.Due to the low microspherical processing speed in this method, there are difficulties in carrying the technique to the industrial level (GÖKMEN et al., 2012).

Fluid Bed Coating
With the fluidized bed coating technique, the solid core material is suspended in a gas stream at a specific temperature.A liquid film is formed on the particle by spraying the liquid into the coating material as fine droplets.Next, the core is gradually wetted and dried to form a solid homogeneous layer that the particles can encapsulate.This method is used to encapsulate various minerals and vitamins used as nutritional supplements in the food industry and to improve the color and flavor of various organic acids in the meat industry (NEDOVIC et al., 2011).One of the most important advantages of fluid bed spray technology is that it provides more uniform coatings using melt or liquid coating materials.The process is controlled by adjusting the spray rate, coating cycle and temperature variables (WANG et al., 2020).Some disadvantages of the method are expensive equipment, long residence time, prone to filter clogging, higher probability of solvent explosion, and poor performance with larger-sized granules as they affect the trajectory (LAWRENCIA et al., 2021).

Freeze Drying
Freeze drying is a method of evaporating moisture from a frozen substrate.This method is preferred over the dehydration process in heatresistant compounds.Freeze drying has three main steps, namely, freezing, primary drying, and secondary drying.Since the temperature used in this method remains low throughout the whole process, it offers better quality products in terms of taste, texture, and aroma.The most commonly used coating materials are maltodextrin, emulsifying starches, whey proteins, and gum arabic (BORA et al., 2019;VAHIDMOGHADAM et al., 2019;WALIA et al., 2019).This method is more suitable for sensitive bioactive compounds.For example, polyunsaturated fatty acids, probiotics, rich in essential oils, proteins and derived peptides, polyphenolic compounds, vitamins, and anthocyanin components in plant seed oils and plants.Because minus temperature is used to freeze the emulsion.The frozen solution is subjected to very low pressures and the ice crystals formed are sublimated.It is also considered an expensive drying technology due to applying a pump that can provide vacuum conditions (REZVANKHAH et al., 2020).

Coacervation
Encapsulation by coacervation has recently received increasing attention due to its practical applications.In this technique, phase separation occurs first to separate the polyelectrolyte and/or _________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ Rev. Inst.Laticínios Cândido Tostes, Juiz de Fora, v. 78, n. 3, p. 102-121, jul/sep, 2023 polyelectrolyte mixture from a solution, then a coacervate phase is formed and the core is completely coated.It has been observed that the potency of coacervate is increased by adding enzymatic/chemical crosslinkers such as transglutaminase or glutaraldehyde.Coacervations consisting of a single biopolymer are called simple coacervation, and those composed of two or more biopolymers are called complex coacervation.(DEVI et al., 2017;SAMAKRADHAMRONGTHAI et al., 2019;WALIA et al., 2019).These technical variants include species using one or more shell types respectively and have been successfully used to capture sensitive bioactive.For example, omega-3 lipids, pharmaceuticals, and plant extracts.Complex coacervation appears to be an effective method for encapsulating sensitive food ingredients.This method allows proteins and carbohydrates to form a complex shell surrounding the nucleus (TIMILSENA et al., 2019).

Co-crystallization
The co-crystallization technique uses sucrose syrup as a matrix surrounding the core material.The sucrose syrup is f saturated by concentrating and the temperature is adjusted to a level that prevents crystallization.Then the encapsulated material is dried to the appropriate moisture content.Between sucrose crystals of nonsucrose materials or microcrystalline clusters ranging from 3 to 30 µm are formed during entrainment.(KOÇ; SAKIN, 2010;GÖKMEN et al., 2012).
Studies on the encapsulation of food compounds by co-crystallization, covering samples of honey, peanut butter, orange peel oil, cardamom oleoresin, yerba mate extract, marjoram extract, and chokeberry, are relatively few (CHEZANOGLOU; GOULA, 2021).
Emulsion methods are frequently used to encapsulate lipophilic bioactive components in the food industry.The size of the droplets produced in emulsion-based encapsulation systems depends on the composition of the system and the homogenization method.An average droplet particle size is <100 nm for nanoemulsions and >100 nm for conventional emulsions.It has been reported that nanoemulsions have better stability against particle aggregation and gravity separation than conventional emulsions due to their small droplet size (AHMED, 2012).Thermodynamically labile emulsions use amphiphilic compounds (lipids, some proteins, peptides, and polymers) to stabilize the dispersed phase, which prevents systems from phase separation.Whey oil-in-water emulsion is one of these compounds that can be dried by different drying methods such as spray or freeze drying (KAKRAN; ANTIPINA, 2014).Such dried capsules can be a ready-made formulation for numerous food products (NEDOVIC et al., 2011).The simulation of the emulsification process with whey proteins is illustrated in Figure 2.

Use of Whey Proteins as Coating Material
Whey is the liquid obtained after removing the casein fraction from milk.It is a blend of proteins with high nutritional, therapeutic, and functional properties.Whey proteins are found in milk at about 0.6-0.7%.Whey proteins are composed of β-lactoglobulin, α-lactalbumin, bovine serum albumin, and immunoglobulins.These proteins are classified into major and minor components.As the main component, whey proteins vary in amount, the concentration of β-lactoglobulin in whey is about 58%, consists of 162 amino acids, and has a molecular weight of 18.4 kDa.αlactalbumin has a molecular weight of 14.2 kDa, 123 amino acids, and constitutes 12% of whey proteins.Bovine serum albumin is approximately 1.5%, while immunoglobulins are about 1% in whey.Minor components of whey include lactoferrin, protease-peptone components, lactoperoxidase, and milk fat globule membrane proteins (SINGH et al., 2009;KRUNIĆ et al., 2019).
Whey is generally obtained from two sources, which are known as sweet and acidic whey.Sweet whey is produced from rennet cheeses; acidic whey is usually made from acid-precipitated cheeses such as cottage cheese (RISNER et al., 2019).The commonly used whey protein products are whey protein concentrates, whey protein isolates, and native whey proteins produced from milk using microfiltration/diafiltration in combination with ultrafiltration techniques (KULOZIK; KERSTEN, 2002;POONIA, 2017).In addition, it is possible to produce native whey proteins from acid whey, sweet whey, lactosereduced whey, and demineralized whey by using other fractionation methods such as chromatography and precipitation.Protein concentration in whey concentrate is between 25-89%, whereas protein concentration in whey protein isolate is 90% or higher than 90% (GÜZELER et al., 2017;BOEVE;JOYE, 2020).
In addition, whey proteins are widely used in the food industry due to their functional and nutritional properties such as foaming, emulsification, hydration, and gelling (ALOĞLU; ÖNER, 2010;KEVIJ et al., 2019;KAUR et al., 2020).
Unlike caseins, whey proteins undergo thermal denaturation when heated at temperatures above about 65 °C and associate with each other through disulfide bond formation and hydrophobic attraction (FATHI et al., 2018).These functional properties of whey proteins make them suitable for capsule wall use.Bioactive molecules have hydrogel-forming abilities and surface activity properties to form encapsulation systems.

Microencapsulation and Nanoencapsulation Techniques
Coating of different food bioactive components by using micro/nanoencapsulation techniques play a critical role in protecting nutrients against adverse processing and storage conditions such as excessive humidity, high temperatures, certain pH values, light, and high oxygen levels.Moreover, these technologies can produce commercialized additives, ingredients, and supplements with a long shelf life that can be applied to food products, cosmetics, and pharmaceuticals.The encapsulation is used for the targeted/controlled release of bioactive compounds within commercial products or the human body (ASSADPOUR; JAFARI, 2019), another advantage of this technique.
Commercial microcapsules typically have a diameter of 3-800 µm, whereas nanocapsules vary between 10 and 1000 nm particle size.Nanoencapsulation is superior to microencapsulation with potential properties such as increasing bioavailability, improving controlled release, and enabling more precise targeting of bioactive compounds (EZHILARASI et al., 2013;FANGMEIER et al., 2019).The size of capsules containing bioactive ingredients affects the properties of functional foods prepared with encapsulated substances.The large capsules can adversely affect the texture of the food.On the other hand, if they are too small, they may not provide adequate protection for the bioactive components.The products formed after the encapsulation process have a micrometer diameter to the nanometer.It is called nanocapsule and microcapsule (YE et al., 2018;AHANGARAN et al

Microencapsulation and Nanoencapsulation studies with whey proteins
Technologically, whey protein-based systems have been used to encapsulate some bioactive ingredients, such as β-carotene, caffeine, epigallocatechin-3-gallate, bilberry extract, palm extract, and encapsulation of probiotics (FATHI et al., 2018).The important studies about microencapsulation and nanoencapsulation, which were carried out with whey proteins are summarised in Table 1.Tan et al., (2019) originally (WPI-Whey Protein Isolate) hydrolyzed (WPI) and gelled whey was used to encapsulate the pepsin enzyme.The study suggested that pepsin could be encapsulated, and its release controlled by combining WPI and gelled WPI in capsules or sandwich tablets (outer gelled WPI-pepsin layers covering the WPI pepsin layer).In another study, Rosolen et al., (2019) evaluated the production of Lactococcus lactis R7 microencapsulated with whey and inulin using the spray drying technique and the ability of microencapsulation to protect against adverse conditions.It was determined that the combination of whey and inulin used as encapsulation material protected bacteria against adverse conditions and showed potential for application as a coating material in foods.

Whey protein Nanoencapsulation
It has been stated that curcumin nano-encapsulated with whey protein may be a potential application that should be considered for clinical applications.

Flaxseed oil/protein hydrolysate Gellan gum-WPI Microencapsulation/ Emulsification
It has been reported that microgels obtained by encapsulating 1.5% whey protein isolate, 0.56% calcium chloride solution, flaxseed oil (15%), and protein hydrolyzate are sufficient to encapsulate bioactive compounds to be released in the small intestine and pass through the stomach without deterioration.Kuhn et al., (2019)

Gallic acid
Pectin-whey protein Nanoencapsulation /spray-drying From the obtained nanoencapsules, it has been revealed that the pectin-WPC complex has the same resistance to precipitation and creaming as Tween 80.
Garlic extract Chitosan-whey protein isolate

Microencapsulation/ Coacervation
The phenolic compound retention efficiency for the encapsulated garlic extract powders ranged from 51% to 61%.Tavares et al., (2019) Grape skin extract Whey protein concentrate (WPC) Microencapsulation/S pray-drying By using whey protein as a carrier agent in grape skin extract, a powder with high anthocyanin retention was obtained after spray drying, showing the potential application in food products.

Microencapsulation/ Emulsification
During covalent bonding and heat treatment between proteins/peptides in hydrolyzed whey protein and maltodextrin; A performance-enhanced component was created during the heat treatment of the model baby food emulsion.

Lactobacillus acidophilus and blackberry juice
Gum Arabic (GA), maltodextrin (MD), and whey protein concentrate (WPC) Microencapsulation/ Spray-drying After encapsulation, total phenolic compounds (TPC) and total monomeric anthocyanin content (TMAC) were higher at 98.4±1.0%and 99.0±1.0%,respectively, when the GA-MD mixture was used as the encapsulation agent.The viability of LA was higher when WPC was used (93.3±0.9%)As a result, the highest protection against oxidation and microencapsulation efficiency is greater than 90%.Gallardo et al., (2013).
Orange peel oil WPC, low methoxyl pectin (LMP), and MD solutions Nanoencapsulation Optimum nanocomplex suspensions containing orange peel oil were formulated at three different pH values (3, 6 and 9) and freeze-dried into powder.Analysis of the size and zeta potentials of the nanocomplexes, the encapsulation efficiency of the smallest particles formed at pH = 6.At pH = 3, 6 and 9, the encapsulation efficiency of the powders was 88%, 84% and 70%, respectively.

Palm fruit feeds Whey protein isolate (WPI) Nanoencapsulation
The study aimed to encapsulate the aqueous extract of palm kernel as a rich source of phenolic compounds.It has been claimed that protein-protein and polyphenol-protein interactions are attenuated at higher extract/WPI ratio.A faster initial release of carotenoids was observed from whey protein matrices than phenolics.Encapsulation of RPW showed a protective effect against pH changes and enzymatic activities during digestion and contributed to increased bioavailability in the gut.Vulić et al., (2019) Resveratrol Gum Arabic-whey protein

Microencapsulation/ Emulsification
The study in which a mixture of gum arabic (GA) and whey protein (WP) was used showed that the stabilized emulsions had >50% encapsulation efficiency for resveratrol.

Nanoencapsulation
/Multiple emulsification A primary saffron water extract in oil (W/O) microemulsion containing 10% (w/w) saffron extract was reemulsified to prepare W/O/W multiple emulsions.Stabilized using 0.25 mass fraction and protein (whey protein concentrate (WPC))/polysaccharide (pectin).With the sequential adsorption of WPC/pectin, good encapsulation efficiency and efficiency for crocin, picrocrocin, and saffron, smooth surfaces in final powders were obtained.Anthocyanins were microencapsulated in a whey protein isolatechitosan matrix in a 78% yield.
According to Tavares et al., (2019), complex coacervates were freeze-dried by complex coacervation method to obtain microencapsulated garlic extract microparticle powders using whey protein isolate (WPI)/chitosan (CH) and gum arabic (GA)/CH combinations as wall materials.Encapsulation with complex coacervation followed by freezedrying preserved the heat-sensitive phenolic compounds found in the garlic extract.As a result of the study, it has been shown that microparticles have the potential to be used as an ingredient in the preparation of food products such as soups and bakery products.Ghasemi et al., (2018) investigated the volatile compounds of chemically unstable D-lime in the presence of air, light, humidity, and high temperature.Therefore, it was subjected to nanoencapsulation with a whey-pectin mixture at different pH values (3, 6, and 9).In the study, the production of nanocapsules loaded with Dlimonene was 0.5% pectin content; 0.75; 1, and whey protein content was studied with 4; 6; 8 %.The study aims to produce an optimized nanocomplex based on viscosity, color, and stability.The researchers determined that the encapsulation efficiency was about 88%.As a result of the study, the optimum whey concentrate-pectin nano complex containing Dlimonene was used in cakes, biscuits, fruit juices, etc.They argued that it could be used in products and that the aroma of this product can be used in this way.
The study of Reddy et al., (2019) aimed to nanoencapsulate coffee bean oil roasted by nanospray drying (NSD).They characterized the structural properties and thermal behavior of the roasted coffee oil capsule obtained from the NSD technique by comparing it with the encapsulation obtained by the conventional spray drying (CSD) process.From the particle size measurement based on dynamic light scattering, they found that the average particle diameter of the nanospraydried capsules was 304.9 ± 99.4 nm.Conventional spray dryer has been shown to produce heterogeneous particle size distribution and micron-sized capsules, and image analysis shows that nanocapsules are approximately 11 times smaller than microcapsules.NSD showed that the coffee oil nanocapsules have a more uniform particle size distribution than their microencapsulated counterparts.
In a study in which the pressurized gas (EAPG) assisted emulsion electrospraying method was performed for the first time to encapsulate bioactive eicosapentaenoic acid (EPA) rich oil in whey protein concentrate (WPC), submicron droplets of EPA oil are encapsulated in WPC spherical microparticles that are approximately 5 m in size.At the end of the research, oils enriched with 80% PUFA at room temperature with emulsion EAPG technology were provided with thermal stability and oil protection without affecting the bioactivity of EPA oil.It is stated that these capsules can be used as personalized medicines or nutraceuticals (ESCOBAR-GARCÍA et al., 2021).D-limonene is a volatile compound commonly used in food flavoring chemically unstable to light, air, humidity, and high temperatures.
In another study in which they obtained the aqueous extract of palm kernel by desolvation with ethanol, they aimed to encapsulate the nanoparticles in whey protein as a rich source of phenolic compounds.It has been stated that the obtained extract-charged particles can be added to beverages without impacting the taste and appearance of the beverages (BAGHERI et al., 2013).Adsare; Annapure, (2021) studied the coconut with a spray-dried technique and mixing whey powders, coconut milk whey, and gum arabic mixture (0. 5, 10, or 15%) with/without curcumin, they obtained different combinations.As a result of the study, they stated that the prey drying process is suitable for the microencapsulation of curcumin, and coconut whey can be used as an alternative encapsulation agent for encapsulating bioactive compounds such as curcumin.
In a study performed by Esfanjani et al., (2015), it was shown that pectin and maltodextrin were able to produce nanoemulsions containing picrocrocin, safranal, and crocin using whey protein concentrate.Fioramonti et al., (2017) found that a multilayer emulsion of flaxseed oil with maltodextrin and whey protein isolate provides >90% encapsulation efficiency, 0.14-0.33water activity.
In nanoencapsulation experiments performed at three different ratios, 70:30, 50:50, and 35:65, it was observed that curcumin's bioavailability has increased and prevented colon cancer by using whey protein.In this study, it was stated that whey protein, which is used to improve the biological activities of curcumin and provide stability for more extended periods, will have the potential to be considered for clinical applications in future studies (JAYAPRAKASHA et al., 2016).In a study using the spray drying method, whey protein concentrate (WPC) and whey protein concentrate admixture of microencapsulated curcumin (TWPC); WPC and TWPC, without changing the technological properties of curcumin, showed a spherical, irregular particle morphology with agglomeration points (GOMES et al., 2021).In another study on curcumin, Adsare; Annapure (2021) investigated both spraydried coconut whey powder and curcuminenriched coconut whey powders for physicochemical properties.As a result, the capsule efficiency for encapsulation in a powder containing 5% whey, coconut milk, and gum arabic 92% with a spray drying efficiency of 66.72% supplied the best conditions in this process.
Due to the increasing awareness of functional food products, it has focused on encapsulating probiotic bacteria with bioactive compounds.Many studies have stated that the co-encapsulation of bioactive compounds and probiotic bacteria in a single product provides synergistic health benefits and improves the adhesion of probiotic bacteria to the intestinal wall.In a study encapsulated in a single whey protein isolate (WPI) -gum Arabian (GA) complex microcapsule with a combination of tuna fish oil (T) and Lactobacillus casei (L), Co-microcapsules (WPI-L)-T-GA) and microcapsules containing L. casei (WPI-P-GA), powdered using spray and freeze drying, and the oxidative stability of Tuna oil in spray-dried auxiliary capsules compared to freeze-dried ones calculated higher.On the contrary, it showed lower probiotic viability (56.19%) (ERATTE et al., 2015).Co-encapsulation of the probiotic strain Lactobacillus casei ssp.with black currant extract resulted in encapsulation efficiency of 87.38% and 95.46%, respectively, when using inulin, whey protein isolate, and chitosan as coating materials (Enache et al., 2020).

CONCLUSIONS
Based on the numerous health benefits of bioactive compounds, the production of functional food products with the application of bioactive compounds has increased significantly in recent years.Therefore, encapsulation applications are crucial for preserving and stabilizing bioactive compounds.Micro-/nanoencapsulation methods are widely used in the food industry.
The delivery of any bioactive compound to various sites in the body is directly affected by its particle size.The encapsulation method is used to protect bioactive compounds from adverse environmental factors such as high temperatures, high oxygen levels, high humidity, exposure to light, and certain pH values, from storage conditions and for controlled release.Nanoencapsulation can potentially increase bioavailability, improve controlled release, and enable more precise targeting of bioactive compounds than microencapsulation.The coating materials used in the encapsulation of bioactive components work in different ways structurally, thus they change their protection capabilities.The effectiveness of any coating material depends on the strength of these structures and their ability to form encapsulation.The main criteria for choosing a wall material for encapsulation are the application of the encapsulants, the bioactive properties of the core, and its cost.
Whey proteins, one of the most important by-products of dairy technology, have an important place in the food industry with their important functional and nutritional properties.It is particularly suitable for creating encapsulation systems for bioactive molecules due to their surface activity and hydrogel-forming abilities in encapsulation applications.
The use of whey proteins in micro/nanoencapsulation is an important technology due to its biological, physicochemical, and technological properties.Moreover, whey proteins are dietary supplements containing all essential amino acids, have high bioavailability, and have a wide range of commercial use.Using whey proteins as a capsule material for encapsulating food ingredients by micro/nanoencapsulation techniques is becoming increasingly common.This reduces the use of whey as a waste material and enables these proteins to show their functional properties as coating material.Therefore, encapsulation applications are of great importance in this respect.At the same time, more research is needed on how the stability of whey proteins against digestive enzymes and their bioavailability may be affected.

Figure 2 .
Figure 2. Simulation of emulsification with whey Source: made by the authors, 2023.