btpr.3138.pdf

Received: 24 November 2020 Revised: 21 February 2021 Accepted: 22 February 2021 DOI: 10.1002/btpr.3138 REVIEW Yeast cells for encapsulation of bioactive compounds in food products: A review Elahe Dadkhodazade1 | Elham Khanniri1 | Nasim Khorshidian2 | Seyede Marziyeh Hosseini | Amir M...

Received: 24 November 2020 Revised: 21 February 2021 Accepted: 22 February 2021 DOI: 10.1002/btpr.3138 REVIEW Yeast cells for encapsulation of bioactive compounds in food products: A review Elahe Dadkhodazade1 | Elham Khanniri1 | Nasim Khorshidian2 | Seyede Marziyeh Hosseini | Amir M. Mortazavian | Ehsan Moghaddas Kia5 3 4 1 Student Research Committee, Department of Food Science and Technology, National Abstract Nutrition and Food Technology Research Nowadays bioactive compounds have gained great attention in food and drug indus- Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University tries owing to their health aspects as well as antimicrobial and antioxidant attributes. of Medical Sciences, Tehran, Iran Nevertheless, their bioavailability, bioactivity, and stability can be affected in differ- 2 Food Safety Research Center (Salt), Semnan ent conditions and during storage. In addition, some bioactive compounds have University of Medical Sciences, Semnan, Iran 3 Department of Food Science and Technology, undesirable flavor that restrict their application especially at high dosage in food Faculty of Nutrition Sciences and Food products. Therefore, food industry needs to find novel techniques to overcome these Technology/National Nutrition and Food Technology Research Institute, Shahid problems. Microencapsulation is a technique, which can fulfill the mentioned require- Beheshti University of Medical Sciences, ments. Also, there are many wall materials for use in encapsulation procedure such as Tehran, Iran 4 proteins, carbohydrates, lipids, and various kinds of polymers. The utilization of food- Food Safety Research Center, Shahid Beheshti University of Medical Sciences, grade and safe carriers have attracted great interest for encapsulation of food ingre- Tehran, Iran dients. Yeast cells are known as a novel carrier for microencapsulation of bioactive 5 Department of Food Science and Technology, Maragheh University of Medical Science, compounds with benefits such as controlled release, protection of core substances Maragheh, Iran without a significant effect on sensory properties of food products. Saccharomyces Correspondence cerevisiae was abundantly used as a suitable carrier for food ingredients. Whole cells Seyede Marziyeh Hosseini, Department of as well as cell particles like cell wall and plasma membrane can act as a wall material Food Technology, Faculty of Nutrition Sciences and Food Technology/National in encapsulation process. Compared to other wall materials, yeast cells are biodegrad- Nutrition and Food Technology Research able, have better protection for bioactive compounds and the process of microencap- Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran. sulation by them is relatively simple. The encapsulation efficiency can be improved Email: [email protected] by applying some pretreatments of yeast cells. In this article, the potential application Amir M. Mortazavian, Food Safety Research of yeast cells as an encapsulating material for encapsulation of bioactive compounds Center, Shahid Beheshti University of Medical is reviewed. Sciences, Tehran, Iran. Email: [email protected] KEYWORDS Funding information bioaccessibility, carrier, cell wall, Saccharomyces cerevisiae, stability Shahid Beheshti University of Medical Sciences 1 | I N T RO DU CT I O N them are 5–500 μm in diameter.2,3 Furthermore, microencapsulation of food ingredients can provide extended shelf life of the final prod- Microencapsulation has been as an efficient technology used in the ucts.1,4,5 Microencapsulation can change physical characteristics of food industry for about 70 years.1 Microencapsulation can be defined material to handle it easier; also, it can provide a diluted sample of as getting a core material surrounded by a wall material usually named original substance's concentration, in cases that we need to use that as shell, membrane, coating, carrier, matrix, or encapsulating material. substance in small amounts.5,6 It has been mentioned that for applying Size of microcapsules ranges from 5 to 5000 μm, but normally most of microencapsulation in food industry considering consumers requests, Biotechnol Progress. 2021;e3138. wileyonlinelibrary.com/journal/btpr © 2021 American Institute of Chemical Engineers. 1 of 12 https://doi.org/10.1002/btpr.3138 2 of 12 DADKHODAZADE ET AL. technological aspects, and economic efficiency are major factors.4,7 GRAS. Moreover, there are some criteria that are effective in the Therefore, it is crucial to find a low-cost carrier which needs simple selection of encapsulating agents such as functionality of the core technology to be used in encapsulation. Also, it should not be repel- material in the final product, concentration of the core material, mech- ling for consumers of the final product. anism of release, stability, and cost limitations.3 These substances Microencapsulation helps to protect useful and sensitive com- should provide high protection degree for the core against environ- pounds such as essential oils, vitamins, and antioxidants or to prevent mental conditions during processing and storage, not react with the undesirable interactions of some ingredients with each other besides core and be easy to work with even at high concentrations.12 Figure 1 protection of active ingredients not to be affected by environmental presents the most common wall materials used for encapsulation of conditions.8,9 In addition to the protection role, it can provide con- bioactive compounds in the food industry.16-18 trolled release of core substances in desired matrix or environment in a specific period of time, thus spontaneously preventing degradation. Microencapsulation may cause improved bioavailability of the core.10 3 | C O M M O N E NC A P SULA T I O N In that case, we can obtain maximum benefit of food ingredient (core M E T H O D S U S ED I N F O O D I N D U S TR Y material) in gastrointestinal tract (GIT) by slowly releasing the core from the capsules in GIT.11,12 Various encapsulation methods have been developed for encapsula- Many foods need to undergo some processes in their preparation tion of food ingredients; the most common types are shown in steps, such as cooking, roasting, baking, frying boiling, and so on. These Figure 2 and are explained as follow: processes may cause nutritional losses as many food components are susceptible to the processing conditions. Therefore, encapsulation of sensitive and unstable ingredients will help to protect them from harsh 3.1 | Spray drying processes. As sensory properties of food products are substantial, this technique can help to mask undesirable flavors or regulate color and Spray drying is one of the most popular techniques for encapsulation texture and produce final products with improved quality. in food industry and is a cost-effective, flexible, and fast process to In food industries, there are various encapsulating materials such produce powdered particles with a good quality.19 In spray drying pro- as proteins, lipids, starches, phospholipids, waxes, and some microor- cess, a solution-containing wall and core materials for encapsulation is ganisms such as yeast cells.2,13 Since yeasts are recognized as Gener- pumped into the heat chamber and rapid atomization of the solution ally Recognized As Safe (GRAS), they are used in human food particles occurs at high temperature by a spray nozzle. The atomized formulations abundantly. Many commercial strains of yeast are avail- droplets fall in the heat chamber of the spray drier and the droplets able for simple use. Among them, Saccharomyces cerevisiae has been are exposed to hot air flow with high temperature (160–220 C). used in bakery and brewing industries for many years.14 Therefore, the water from these droplets evaporates rapidly and they Yeast cells are key components of fermented foods like bever- are dehydrated. Then, dried end product is separated from the drying ages, bakery products, and cereals. In fermentation industry and pro- air with a proper outlet temperature.20 Spray drying is a simple and duction of metabolites via biotechnology, using yeast cells have been relatively easy method for industrial settings. However, it has some a major part of these processes; yeast cells play an important role in drawbacks for temperature-sensitive molecules (protein carriers) that alcohol production, manufacture of single cell proteins (SCPs) as a may degrade at high drying temperatures and nonenzymatic browning nutritional feed, production of many enzymes, and also wastewater can happen in the system.21,22 Also, high inlet temperatures could recycling. However, the bland taste, color, and low cost of yeast cells affect activity of chemical bioactive compounds as well as probiotic make them attractive in food industry. Yeast microcapsules (with any bacteria.23 Yeast cells are successfully applied as a carrier material by food ingredients) can be used in bakery and confectionary products, spray drying.24,25 In a study by Sultana et al. (2017), it was observed chewing gum, sauces, semi-ready foods, and cereals. Microcapsules that the inlet air temperature of 200  C had no effect on the amount can be made in tablet or powder forms, keeping the core materials of encapsulated ethyl hexanoate with dried S. cerevisiae cells by spray safe and release them by hydration.14 Also, in pharmaceutics, cells of drying.26 Ruphuy et al. encapsulated curcumin and ibuprofen drugs in S. cerevisiae have been used for microencapsulation of acyclovir and yeast glucan particles by spray drying and investigated the effect of berberine.2,15 This article reviews the encapsulation potential of yeast initial solid content and atomizing droplet size on encapsulation effi- cells for bioactive compounds in the food industry. ciency (EE). Their research indicated that encapsulated drugs in com- parison with the micronized crude drugs had faster dissolution rates. In addition, higher amount of initial solid and larger atomizing droplet 2 | COMMON ENCAPSULATING size increased EE.24 In another study, the stability of encapsulated D- M A T ER I A L S US E D I N F OO D I N D U S TR Y limonene and ethyl hexanoate in S. cerevisiae and maltodextrin using spray drying was evaluated. The authors announced that yeast cells Several ingredients can be utilized as coating materials for entrapment had higher retention capability for both types of flavor and oxidative of liquids, solids, and gases with different properties.1 These sub- products of flavors were formed in the spray-dried yeast powder less stances should be certified for food applications and included as than maltodextrin powder.18 DADKHODAZADE ET AL. 3 of 12 Wall materials Polysaccharides Yeast cells Proteins Lipids Gums: Carbohydrates: Others: Alginate Starches S. cervisiae Plant based: Animal based: Waxes: Phospholipids Guar Maltodextrin Milk proteins Beeswax Fractionated fats Pectin Dextrins, Chitosan Y. lipolytica Soy Proteins Glycolipids Xanthan Cellulose and their Corn Proteins Egg proteins Carnauba wax Mono- and di- Gum arabic derivatives Pea Proteins glycerides FIGURE 1 Common wall materials for entrapment of bioactive compounds in microcapsules.7-14 Microencapsulation techniques Chemical Physical/mechanical Interfacial Phase polymerization Coacervation Liposome Spray drying separation Solvent Extrusion formation evaporation Emulsification Fluidized-bed Emulsification coating FIGURE 2 Types of encapsulation methods used in food industry 3.2 | Extrusion and are solidified to capsules by chemical or physical process.28 Beads produced by this technique may have various sizes, from micrometers Extrusion technology is a basic encapsulation technique for micro- to millimeters. The capsules with larger size are dispersed more diffi- organisms, because the process can be performed at low tempera- cult than smaller capsules in the food. Therefore, the large particles 27 ture in aerobic and anaerobic conditions. The extrusion process are unfavorable in foods such as chocolate and condensed milk.29 In involves extrusion of a biopolymer solution and bioactive substances general, the effective factors on size and shape of the particles include through a needle, which droplets are formed at the end of the needle needle diameter and flow rate of the encapsulating material.30 4 of 12 DADKHODAZADE ET AL. Different polymers can be utilized by this technique. Grosso et al. processes due to their resistance to heat resulting in higher stability of reported the improved survival of probiotic bacteria (Lactobacillus aci- flavor until the time of consumption. It seems that flavor encapsula- 31 dophilus and Bifidobacterium) by encapsulation in calcium alginate. tion in yeast cells can solve concerns about flavor loss during high Also, some authors mentioned that encapsulated cells have more temperature processes of food production as well as long lasting resistance to the acidic environments and thermal condition than free release.42 cells and encapsulation by this technique improved their stability in It has been mentioned that using yeasts as a coating in encapsula- acidic media. Large-scale production by this method is difficult and tion is highly cost effective because of simple process.14 However, leads to low productivity. The size of particles is large and it is another using fresh culture of yeast may increase expenses, but the procedure issue, which makes it unsuitable for industrial application.13 of encapsulation is very much simpler than other carriers without need of buying and using additional materials. Microorganisms (S. cerevisiae) were recognized as a carrier in encapsulation process in 3.3 | Coacervation early 1970s.43 It has approximately 5 μm diameter in average cells.44 Some other strains that have been used for microencapsulation are Coacervation is a modified emulsification method with up to 99% Torulopsis lipofera, Saccharomyces bayanus, Endomyces vernalis, and encapsulation yield. In this method, bioactive components are added dairy yeasts like Candida utilis and Kluyveromyces fragilis14. S. cerevisiae 13 to a polymer solution and spherical droplets are formed. According can be considered as an ideal, applicable, and well-known container in to Beikzadeh et al., after adding omega-3 fatty acids to S. cerevisiae encapsulation technique used for microencapsulation of many bioac- cells and β-glucan, the amount of loading capacity for yeast cells was tive compounds. In a study by Karaman,45 plasmolysed (PYC) and non- higher in comparison with β-glucan. 32 In addition, the reported loading plasmolysed S. cerevisiae yeast cells (NPYC) were used as capacity for thymol and carvacrol of Zataria multiflora Bioss. essential microcarriers for encapsulation of thymoquinone (black cumin seed oil encapsulated in S. cerevisiae cells were 44.53 and 30.88%, respec- oil). The results indicated that bioactivity of thymoquinone was tively and no significant difference was observed in antibacterial activ- protected better in PYC and the PYC samples showed the lowest deg- 33 ity of essential oil after encapsulation. Encapsulation by radation ratio of thymoquinone (52.63%) during 8 days storage. In coacervation can be achieved with simple and complex methods. In a another study, Dadkhodazade et al. investigated the ability of simple process, only one polymer such as alginate, gelatin, and pro- S. cerevisiae cells for encapsulation of cholecalciferol (vitamin D3). teins is used, while in complex method, two or more colloidal solu- They reported that the spray dried and plasmolysed yeast cells tions are used. The complex coacervation is more suitable for showed the highest EE (76.10 ± 6.92%) at initial vitamin D3 concen- encapsulation of hydrophobic compounds.34,35 Coacervation has high tration of 2.5 mg per gram of yeast cells.25 Cell wall and its eukaryotic value for encapsulation of functional compounds, such as polyphe- structure and plasma membrane made it special as a physical barrier nols. However, the experimental parameters need to be carefully against environmental components like oxygen or free radicals and 22 controlled. light radiation.30,37 Cell wall properties can result in sustained release of core in a way that dry yeast cells are a good protector of core material.5,30 Two parts of yeast cells can be used for encapsulation, 4 | YEAST CELLS AS ENCAPSULATING namely, cell wall and plasma membrane. Nguyen et al. explored stabil- MATERIAL IN FOOD PRODUCTS ity of Hibiscus sabdariffa extract (anthocyanin source) encapsulated in cells of S. cerevisiae. They optimized the process and an EE of 27% Yeast cells are natural micro-containers for microencapsulation of was obtained. Storage stability of encapsulated pigments was studied both fat-soluble and water- soluble food ingredients.6,11 Firstly, it was in water and buffer (pH 1.5) at different time and temperatures. The mentioned that water soluble flavors can pass the yeast cell and results showed that the stability of microparticles was higher in sam- remain in it as a core material.36 Then, it was implied that fat soluble ples with heat treatment compared to those without heat treatment. substances can be entrapped in yeast cells with more than 70% lipid It was related to enzymatic activity of yeast cells when cells were not content.37 Finally, AD2 Ltd (1987) found that cells with low lipid con- subjected to heat treatment. On the other hand, acidic pH had an tent ( autolyzed > pulsed Diffusion coefficient (Deff) assessment 67 pressure homogenization electric field treatment Ascorbic acid Water soluble Enzymatic hydrolysis EY 101.90 ± 5.5%, Adding maltodextrin in some emulsion 60 samples Cholecalciferol Oil soluble Plasmolysis by NaCl Max EE 76.10 ± 6.92% 25 Probiotic bacteria Water soluble Physical destruction through milling EE 88.33% Probiotics was coated by two layer of calcium 52 chloride, the third coating was cell wall and another calcium chloride layer. Purslane seed oil Oil soluble Plasmolysis by NaCl EE 60.27% Carboxy methyl cellulose (CMC) was used as 39 second coating. Berbrine Water soluble — LC 78% 15 Resveratrol Oil soluble Plasmolysis by NaCl EY 4.52% 10 Limonene Oil soluble Plasmolysis (Patent EP0453316A1) 42 Menhaden fish oil Oil soluble Autolysis with ethyl acetate Control 32.6 ± 2.8 In addition of yeast cell coating, there is an 6 Enzymatic hydrolysis with b-glucanase -Autolysis 39.4 external coating of hydroxypropyl -Autolysis with ethyl acetate 44.6 methylcellulose (HPMC) -Hydrolysis with Glucanex R200 36.3 -Combination of autolysis and hydrolysis 45.3 Chlorogenic acid Water soluble Plasmolysis by NaCl Max EE 12.6% 40 (CGA) Limonene Oil soluble Plasmolysis (Patent EP0453316A1) EY 26.7% 75 Orange peel and Oil soluble Pretreatment by sodium azide Max EE 40% 38 peppermint oil 5 of 12 6 of 12 DADKHODAZADE ET AL. FIGURE 3 A schematic structure of yeast cell S. cerevisiae cell wall is composed of 10 nm layer of mannoproteins digestion and encapsulated curcumin released in intestinal compart- which are highly glycosylated and a network of 1, 3-β glucans, and ment without any changes in the cell walls.53 1,6-β glucans are connected to a thin layer of chitin under them. The The amphiphilic nature of cell wall due to the presence of man- thickness of the cell wall is about 70–100 nm, it consists approxi- noproteins made it a bio-emulsifier. Manos and polypeptide chain mately 15–25% of cell's dry mass.41,44 β-glucans and chitin stand for showed hydrophilic and hydrophobic properties, respectively.54 Dif- 41 cell rigidity and mannoproteins provide cell porosity. Cell permeabil- ferent strains of baker's yeasts have been used to extract man- ity can be increased by implying chemical treatments. Any modifica- noproteins to be applied in food products.55-57 Dikit et al. used tions that affect mannoproteins and disrupt disulfide bonds and S. cerevisiae KA01 isolated from palm wine and the emulsifier obtained hydrophobic linkages can change porosity.48 from this strain had potential application in salad dressing. The As Zelotnik et al. reported, in aqueous solution, small polar mole- extracted mannoproteins could be used at pH 5–8 and extreme condi- cules or nonpolar ones can pass through the cell wall easily, but the tions of temperature and salinity in food industry.55 Also, there are restrictive factors are the size of molecule and also polarity properties studies which used Yarrowia lipolytica (Y. Lipolitica) to extract emulsi- of the cell. Only molecules with molecular weight of less than 620 Da fier.58,59 Amaral et al. named the extracted bio-emulsifier “Yansan” with a limited molecular radius of 0.81 nm dimensions can freely pass which had high emulsification activity and formed a stable water in oil through the cell wall.49 It has been proved that yeast cell wall has anti- emulsion in pH range of 3–9.59 Yeast cell by-products have been used mutagenic and antigenotoxic activity associated with free radical scav- in microencapsulation process. According to Marson et al, Maillard enging properties of the yeast cell wall. Also, β-D-glucan can conjugates of hydrolyzed yeast cell debris of Saccharomyces pas- potentially prevent lipid peroxidation and inhibit the oxidative dam- torianus were a good choice of encapsulation carrier for ascorbic acid ages of DNA.50 In a survey, the preventive effect of yeast cell wall on by spray drying process. Enzymatic hydrolysis led to degradation of cancer cells in a mice was confirmed.51 proteins and enhanced cell wall porosity and promoted rupture of Besides using whole yeast cell in microencapsulation, cell wall can yeast cells. β-glucans as main functional ingredients of cell wall in be used as a carrier by itself. Mokhtari et al. used alginate micro-beads encapsulation process were remained after hydrolysis.60 Hamza et al. for encapsulation of probiotic bacteria (L. acidophilus and B. bifidum) used glucan mannan lipid particles of S. cerevisiae cell wall for encap- followed by coating by cell wall of S. cerevisiae. Then, they were added sulation of humic acid. As yeast cell component could show biological to grape juice and the juice properties was assessed during storage degradation of mycotoxins effects, these microparticles help detoxifi- time. Results demonstrated that coating of bacteria with yeast cell cation of aflatoxin B1 in SGF.61 Vélez-Erazo et al. encapsulated sun- had a positive effect on survival of L. acidophilus, but had no effect on flower oil in spent brewer's yeast (as by product) and also evaluated B. bifidum. Also, it caused some changes in color of juice and its tur- emulsifying ability of these yeast cells. They used enzymatic protein bidity.52 Young et al. (2020) evaluated bio-accessibility of curcumin hydrolysis of yeast cells and applied the concentrated hydrolyzed pro- encapsulated in native cells (S. cerevisiae) and yeast cell wall particles tein as emulsifying agent. Their findings showed that higher protein during simulated gastrointestinal digestion. They mentioned that yeast concentration led to more stable emulsion. Also, spent brewer's yeast cell wall particles indicated faster intestinal release after gastric could enhance oxidative stability of the loaded oil.62 DADKHODAZADE ET AL. 7 of 12 4.2 | Plasma membrane from the cell and more space is provided for loading of core mate- rial.68 Many compounds have been used for plasmolysis such as some There is an inner layer surrounded by cell wall (