1 Introduction to propolis

In recent years, technological advances in biomaterials have sparked considerable interest due to the extensive number of useful and valuable applications, such as tissue engineering, heavy metal removal from the environment, drug delivery, and food storage [1,2,3]. Propolis was reported as natural material extensively applied in traditional and alternative medicine and other bee products [4]. Propolis has been used as an effective anti-bactericidal, antiviral, and antifungal bio-product in treating human inflammations [5]. The composition of propolis varies depending on where and when it is collected and differs owing to the plant source [6]. Honeybees collect it from the leaf buds of different tree species, and it contains more than 160 identified components, among which phenolic compounds, mostly flavonoids, are the main components [7]. Propolis contains antioxidants that prevent oils and serum lipoproteins from oxidizing [8].

Propolis, bee glue, is a wax-like natural resinous material produced by bees by mixing plant resins with bees’ saliva, wax, and pollen to produce the last material which is utilized by honeybees as a protective coating for the inner walls of the beehive [9]. Figure 1 shows the chemical composition of propolis, which contains resins (50%), composed of flavonoids and phenolic acids; waxes (up to 30%), essential oils (10%), pollen (5%), and other organic substances (5%), are usually included. The raw propolis, aqueous extract, and ethanolic extract were proven antimicrobial reagents due to their polar phenolic substances, especially the flavonoid portion [10].

Fig. 1
figure 1

Chemical composition of propolis [11]

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Table 1 shows some phenolic compounds identified in propolis extract by gas chromatography-mass spectrometry [12]. However, a recent study showed that it contains more than 300 constituents. The biological activity is originated from effective substances such as flavonoids, terpenes, caffeic, ferulic, and coumaric acids and esters [13]. Figure 2 shows the chemical structure of the main bioactive compounds in propolis [14]. The antiseptic, anti-inflammatory, antioxidant, antibacterial, antimycotic, antifungal, antiulcer, anticancer, and immunomodulatory properties of propolis make it an important part of traditional medicine. Moreover, the free radical scavenging ability may consider an essential property of propolis for utilizing it in an encouraging manner [15].

Table 1  Compounds identified in propolis extract by gas chromatography-mass spectrometry
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Fig. 2
figure 2

Chemical structures of propolis bioactive compounds [14]. License Number 5446960510218, 13/12/2022, Elsevier

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There are diverse types of propolis owing to their color, geographic region, and extraction methods. The color of propolis changes from yellow to dark brown according to the location, season, bee species, and available plants for bee feeding [16].

Regarding the food industry, there are a few relevant obstacles to the widespread use of propolis. One of the biggest obstacles is propolis’s characteristic taste and flavor, which adversely affects the product’s sensory qualities. Because raw propolis contains high contaminants and is poorly soluble in water, raw propolis cannot be used directly in food products. Propolis must be extracted with solvents to increase the concentration of active ingredients [17]. The aim and the novelty of this review are to shed light and clarify the importance of propolis and how to use it as an additive to foodstuffs without affecting the properties and taste of the product.

2 Food packaging overview

Microbial contamination in food is primarily caused by collecting, shipping, and packaging. Many pathogenic bacteria are found on plants, including Escherichia coli and Staphylococcus aureus. As they are stored, they are susceptible to spoilage, resulting in fungi growth. Such products can be contaminated if they are not adequately cleaned or processed before consumption. Searching for bioactive materials will keep vegetables against the growth of pathogens and the spoilage caused by fungi [18]. The losses in the postharvest industry result from fungi that contaminate fruit and grow disease. Various fungicides are used to control postharvest fungi, such as inorganic substances and artificial chemicals. New alternatives should be explored to meet the increasing requirement for safe and nutritious food [19].

As a protective layer formed on food surfaces, edible coatings are thin sheets of organic materials such as proteins and polysaccharides. Utilizing natural extracts for food protection has received growing interest in constructing effective edible coatings as an appropriate substitute to reduce fungal pathogens in fruits during postharvest shelf life [20]. Propolis, a natural and safe compound, was investigated for food preservation due to its antimicrobial and antioxidant activities [21]. Propolis was being used as a natural additive in dairy beverages and fruit juices [22]. A review also described the antibacterial effect on other foods such as vegetables, fruits, eggs, and meat by Bankova et al. [23]. A growing interest in employing propolis for packaging methods planned to keep products fresh and optimize their shelf life has increased [24].

Propolis, which has been successfully employed mainly in the pharmaceutical business, was chosen as the active component for producing natural packaging materials [8, 25]. Coating techniques were employed to place active layers on plastic films and cellulose sheets to accomplish this goal. This technique showed the polyphenols’ gradual breakdown over time consequently extending the stability of the generated active coatings.

Biodegradable active polysaccharides are a promising green strategy for reducing widespread worries about environmental pollution and human health issues that evolved from using plastics [26,27,28,29]. For example, the creation of active films based on chitosan, made from discarded crayfish shells enhanced with bioactive extract (5–20%) of propolis, showed promising capabilities for food packaging applications. The results established that adding PS improved the films’ thermal stability and mechanical characteristics, such as their yield strength, stress at break, and tensile modulus. Moreover, it improved antibacterial and antioxidant functions. Overall, CS-based composite films appear to be a viable environmentally benign replacement for petroleum-based synthetic polymers, allowing food goods to have longer shelf lives due to their eco-friendliness [30]. Moreover, the addition of 10% ethanolic extract of propolis and 33% chitosan nanoparticles into edible film formulations provides pertinent information on edible propolis-chitosan nanoparticle films for strawberry preservation. Consequently, using these films in packaging applications in the future holds promise for extending the shelf life of food goods [31].

Mustafa, et al. prepared biodegradable active and intelligent films that would later be applied to food packaging. The results showed that increased PE content was associated with high anti-bacterial activity. The bacterial attack retaliation at higher PE concentrations and a color-change reaction were also seen in food rotting tests. The prepared films were examined on pasteurized milk to regulate their potential applicability. Both an anti-bacterial response and color change were evaluated to prevent and detect food spoiling using an active and intelligent food packaging system [32]. In the field of chicken kebabs preservation, propolis aqueous extract can inhibit the growth of bacteria in marinated chicken breast for 12 days at 5° C. The samples' shelf life was dramatically increased to 6 days by the addition of the propolis extract. The rise in pH and TVN might be controlled by propolis extract. The sensory characteristics of pre-cooked kebab chickens were also improved by using propolis aqueous extract; as a result, the odor alterations in the propolis extract-containing samples happened more gradually than in the control samples. Adding propolis extract up to 8% v/w had no discernible detrimental effects on the color and general acceptance of the samples. The propolis extract significantly improved the textural parameters of marinated chicken breast. These results showed that it is feasible to substitute chemical preservatives in ready-to-cook poultry products without compromising the goods' quality or shelf life or their appeal to consumers [33].

Khodayari, M. et al. added propolis ethanolic extract and Tanacetum balsamita essential oil to poly(lactic acid)/cellulose nanocrystal polymer sheets before being cast in a solvent. These films showed high antibacterial efficacies and long shelf life of cooked sausages by 50 days when kept in the refrigerator [34].

Due to its unique qualities, such as film-forming, barrier property, and antibacterial activity, propolis extract conjugated with chitosan in edible coating formulation could be employed as a food-grade composite for coating eggs. In addition, the formulation can maintain albumen quality, store HU at a high level, prevent pH from rising, stop water and weight loss, boost eggshell thickness and strength, and reduce microbial contamination [35].

Edible films based on natural cassava starch, beeswax, and ethanolic propolis extract were created effectively. Starch was added to produce larger thickness and water vapor permeability values. Beeswax and ethanolic propolis extract were added to natural cassava starch to adjust the microstructural in the starch molecules. When compared to edible films made using a different lipid source, obtained edible films had lower values for water vapor permeability and water solubility and were more soluble in acidic than alkaline solutions. The moisture content and vapor water permeability decrease with increasing beeswax concentration, which is crucial for applying edible films and coatings on fruits and vegetables. The addition of propolis to native films made of cassava starch showed antibacterial efficacy against Aspergillus niger, but it also diminished the films’ lightness, making them opaque and yellow-colored [36].

3 Propolis applications in food packaging

3.1 Films

Perishable foods, including meat, dairy products, and cooked leftovers, can benefit from adding chitosan to the packaging as an effective antimicrobial reagent for preserving the quality and extending the shelf life [37]. With its high polyphenol content and wide range of biological actions, propolis can be integrated into films as an effective reagent. Chitosan films containing various ratios of propolis extract were established. Additionally, combining chitosan and propolis decreases the water vapor/oxygen permeability index, which enhances the potential for using chitosan-based propolis sheets as effective ingredients for food packaging [38].

The antimicrobial efficiency of chitosan-coated polypropylene blends alone and incorporated with ethanolic extract of propolis was assessed against various foodborne pathogens. The chitosan-treated film demonstrated a distinct spectrum of antibacterial action. Incorporating polypropylene into the coating at 10% (propolis resin/chitosan) improved antimicrobial action against all pathogens examined. The results propose that coating chitosan onto the food-contact surface of synthetic polymer films’ is a viable approach for producing antimicrobial packaging substance. Furthermore, the antimicrobial properties of propolis make it the ideal biomaterial for coatings and blends based on biopolymers [39].

By using chitosan, including propolis-ethanolic extract, as a coating biopolymer, fruit quality losses were minimized. In contrast to the control papayas, a decreased deterioration index and infection width were found, which resulted in a 2-day increase in shelf life [40]. Furthermore, in using propolis extract as a component for food preservation, a linear relationship between the zone of cellular growth inhibition and concentration was observed [39]. Table 2 summarizes some recent studied concerning packaging films with propolis additives.

Table 2 Packaging films with propolis additives
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3.2 Active and intelligent packaging

As part of the active packaging system, the food should be able to interact with it, for example, by releasing effective substances that afford protection against microbial spoilage. Propolis can be fully utilized to accomplish a long shelf life by utilizing its antimicrobial and antioxidant properties. During the paper production process, a large amount of active and free water molecules are generated by incorporating propolis extract into the matrix to the system’s equilibrium [48].

Active and intelligent food packaging films were developed based on polyvinyl alcohol and starch, as biodegradable polymers, incorporated with natural propolis extract additives (PE) up to 20% and anthocyanin from rosemary extract using boric acid as a cross-linker. The results proved the compatibility of films mixture with high mechanical strength and anti-bacterial activity. Films responded visibly by changing color and protected milk from spoilage [49]. Cellulose-based packaging materials, which contain additional chitosan/propolis complex, have exciting capabilities for the food packaging sector. The blends of cellulose/chitosan/propolis have been achieved in providing enough active polyphenols in paper production which release in contact with moist food to develop an antimicrobial action. The blending of propolis and chitosan improves the antimicrobial and antioxidant capacity paper and cellulosic packaging sectors [50, 51].

Food packaging research and innovation have focused on incorporating bioactive substances and ingredients. The use of bio-based packaging substances with antioxidant and antimicrobial properties is becoming increasingly popular since oxidation and contamination caused by microorganisms are the main concerns for food safety and quality [52]. As a promising biodegradable, effective food package, propolis shows excellent potential. In addition to being a valuable supplier of polyphenols with various biological activities, propolis is an effective active agent that can be used in film [38].

Promising trials have been carried out to improve the release of active materials at rates appropriate for a wide range of food packaging applications. Incorporating propolis into polylactic acid sheets controlled by polyethylene glycol and calcium bentonite was adjusted through the casting technique. In this case, the delivery system would be a very efficient way of delivering the active agents because some polyphenol acids would be released into the food. Other flavonoids, in contrast, stay in the polymer to become active at the food-polymer interface. The incorporation of propolis in the biopolymer may present a probable delivery method for food packaging sectors. Antimicrobial packaging contains additives that release gradually into the food to avoid microbial growth. As a result of their incorporation into the packaging materials, they are protected from oxidation or degradation reactions and remain active for the lifetime of the food item [53]. Incorporating propolis and yerba mate extracts into carrageenan-starch blends establishes a practical approach for improving new influential films with antioxidant properties. Food products can be preserved by preparing biopolymeric matrices that deliver bioactive compounds [54].

Promising composite materials consisting of cellulose nanocrystals (CNC) and polylactic acid were produced by combining Tanacetum balsamita essential oil and propolis ethanolic extract through a solvent casting technique. The antimicrobial effectiveness of the composite extends the shelf life of vacuum-packed cooked sausages to 50 days of refrigerated storage. Furthermore, the results showed that the formed composite materials with antimicrobial reagents such as propolis and essential oils might be a good platform for developing biodegradable packaging [34].

Active gelatin films were loaded with propolis extract in combination with clove and/or basil essential oil. By combining these components in gelatin, the content of total phenols was increased, a radical-sequestering function was enhanced, and antimicrobial properties were enhanced. The addition of these components in the gelatin matrix increased the content of total phenols and the sequestering activity of radicals and antimicrobial activity. These results indicate that these films may be suitable for food preservation with low moisture percentage and sensitivity to lipid oxidation. In addition, as a result of adding essential oil, the optical and UV/visible light barrier properties were improved, which may lead to better protection against lipid oxidation [55].

Polylactic acid films containing different contents from propolis extract, as an active agent, showed antioxidant effect on dry meat sausage. These films offer active packaging that may extend meat products’ shelf life [56].

3.3 Coatings

3.3.1 Edible coatings

Food packaging often uses edible coatings as they are economical and environmentally friendly. These coatings consist of thin films of hydrophilic and hydrophobic materials, such as polysaccharides (e.g., sodium alginate) and proteins (e.g., sodium caseinate), and non-polar materials (e.g., vegetable oils and resins), that can be applied to a wide variety of foods, fruits, and vegetables [57].

In addition to preserving food, edible coatings improve the flavor and texture of meat products. Due to their acceptable influences, it is possible to use these biopolymers as the main ingredient for the next generation of packaging. For example, edible coatings based on gelatin containing propolis were established and utilized for raspberries to prolong their shelf life. The presence of propolis extracts altered the mechanical property of the films to become more flexible edible sheets but still colored with lower transparency. In addition, the tested fungus was significantly inhibited by the active films [57].

The impact of dipping poultry meat in a propolis and chitosan coating supplemented with Zataria multiflora essential oil was assessed. The chitosan enriched with propolis and Zataria multiflora essential oil showed a great antibacterial and antioxidant influence against some bacteria and may improve the chemical and organoleptic properties. This combination was suggested as an active packaging material because it extends the shelf life of chicken breast meat to more than 2 weeks. Various trials have been carried out to evaluate the synergistic antimicrobial and antioxidant properties through mixing propolis and chitosan against food spoilage microorganisms and lipid oxidation [58, 59].

The natural antioxidant and antibacterial properties of chitosan and propolis may effectively extend the shelf life of Nemipterus japonicus. For example, chitosan containing propolis delayed the growth of total bacteria and decreased refrigerated fillets’ deterioration. In addition, chitosan combined with propolis may successfully reduce lipid oxidation and protein decomposition. Chitosan and propolis as antioxidants and antibacterials were presented as promising materials for maintaining the storage quality of Nemipterus japonicus and expanding its shelf life [58]. The chitosan coating with propolis improves food’s microbial, chemical, and sensory quality, enhances shelf life, and maintains its quality through synergistic effects [37].

The edible coating has been reported as a promising technique for fruit or vegetable protection, enhancing its shelf life, keeping the product against pathogens, and hindering spoilage. The incorporation of nanoparticles into edible coatings improves their mechanical and antimicrobial properties and consequently improves the shelf life of food [60]. Moreover, incorporating propolis into chitosan coatings enhanced the protection of fresh-cut broccoli [31].

Edible films based on hydroxypropyl methyl cellulose with different concentrations of propolis were evaluated. The incorporation of propolis improves the water vapor permeability and gives rise to more rigid, less flexible, deformable, and colored films with reduced gloss and transparency. The formed composites showed a distinguished antifungal property and a superior inhibition of A. niger. The properties of hydroxypropyl methyl cellulose films containing propolis improved the water barrier properties. Moreover, the presence of propolis maintained the antifungal activity of this bioreagent; as a result, it may be applied to regulate the fungal degeneration in foodstuffs [10].

There is a strong odor and unpleasant taste to propolis, and consequently, its encapsulation in edible films for food preservation can regard as another way of its consumption. Edible coatings based on hydroxypropyl methyl cellulose containing propolis were established and applied to inhibit weight loss and browning of muscatel table grapes. Moreover, these coatings improve gloss and microbial safety and control the growth in oxygen utilization through cold storage. In addition, propolis incorporation enhanced the grapes’ color luminosity [8].

Cassava starch, beeswax, and propolis-based edible films showed lower water vapor permeability than films made with another lipid source. The amount of beeswax and moisture content decrease when the beeswax concentration increases, which is essential for utilizing edible films and coatings on fruits and vegetables. Although adding propolis to films exhibited antimicrobial activity against A. niger, it reduced their transparency, resulting in opaque and yellow-colored films [36].

Silver nanoparticles were made and conjugated to Aloe vera gel using propolis extract and microwave heating. Several bacterial and fungal strains were tested against the coating to determine its effectiveness as an antibacterial and antifungal. Food commodity packages can last longer by incorporating antimicrobial, edible coatings that have desirable barrier properties. It has been shown in several studies that rice by-products and propolis can be used for the preparation of edible coatings [61, 62].

3.3.2 Eggs coating

Despite their excellent protein content, eggs are a perishable product. Various methods can preserve food, including applying protein coatings combined with antimicrobial agents, such as propolis. An evaluation of the effect of rice protein coatings combined with propolis on the interior feature and eggshell breaking strength of fresh eggs through storage below 20 °C for a long time was conducted. By treating eggs with rice protein and propolis, the quality of eggs was preserved for a longer time than without treatment. At concentrations of 0, 5, and 10%, the propolis solution was added to the rice protein solution. Eggs have been successfully extended in shelf life using rice protein and propolis as coatings [61].

Propolis has been studied for its effects on egg weight loss, hatchability, chick performance, and reduction of the bacterial activity happening on eggshells. Results showed that propolis could be used as an alternative to chemical disinfectants for hatching eggs without adversely affecting quail chicks’ hatchability and performance. Customers have considered propolis to be a safe alternative preservative agent. During storage, propolis-covered table eggs improved the interior egg quality. As a result of this study, propolis may render hatching eggs safe, non-toxic, and effective [63]. In addition, propolis extract protects the internal egg quality parameters when applied to shell surfaces [64].

Combining propolis extract with chitosan in an edible coating formulation can afford a food-grade composite with exceptional features such as film-forming, barrier properties, and antibacterial action, which could be used as a food-grade coating for eggs. An eggshell coated with chitosan-propolis extract may maintain albumen properties, avoid pH fluctuations, maintain weight and thickness, and reduce microbial contamination [35].

3.3.3 Fruits coating

Using chemical fungicides can be detrimental to human health and the environment, while they cannot provide physical protection. In long-term storage, physiological and biochemical losses and phytopathological agents result in significant fruit deterioration [57]. Many different agricultural products have the potential to be contaminated by Aspergillus flavus. Fruits are protected against humidity, oxygen, and solute transition by bio-coating. The bio-coating is intended to be consumed with fruit, so it needs to be made from natural materials, such as propolis. Results showed that fruit treated with 0.50% propolis was most promising. According to the study, 0.50% propolis inhibited ripening and increased biosynthesis of nutritional components such as total flavonoids and antioxidants. The quality of dragon fruit was significantly altered when treated with different amounts of propolis extract [65].

Nanoparticles of chitosan and propolis at a concentration of 40% showed significant inhibition on the spore germination and, mainly, on the aflatoxin creation of A. flavus [66]. By reducing weight loss, increasing fruit firmness, preventing fruit browning, and reducing decay incidence, biomaterials maintained postharvest quality in loquat fruit. If treated with 0.5% propolis extract, loquat fruits can be stored for 35 days without deterioration [67].

Using natural polymers as antimicrobial substances have been reported as promising method to reduce contamination [68]. A pullulan coating containing either 5 or 10% propolis was evaluated for its impact on cherry tomatoes during refrigerated storage. Mixing propolis with the pullulan coatings improved the antimicrobial properties and increased their activity while lowering cherry tomatoes’ weight loss and maturation time. Microorganisms were diminished, and the ripening process was delayed owing to propolis; thus, the shelf life was extended. Tomatoes did not taste or smell differently after being coated in propolis while enhancing the skin’s brightness, making coated cherry tomatoes more appropriate for inspectors [69].

The effect of propolis coating on tomato preservation and the best concentration to use were investigated by applying different concentrations of propolis extract to tomatoes. Applying 10% propolis as bio-coating decreased the rate of weight loss and preserved fruit firmness [70]. Egyptian propolis was evaluated to reduce tomato bacterial wilt produced by Ralstonia solanacearum under greenhouse and field conditions [71]. Moreover, propolis decreased the respiration rate of sweet cherry; decreased weight loss; delayed the decline of titratable acid, soluble solids, and fruit hardness; and slows the loss of fruit vitamin C. Propolis keeps cherry fruit fresh for a long time [72].

Propolis was evaluated as a bio-coat of the tangerine by dip process for a short time [57]. Wax inside propolis offers hydrophobic properties that allow propolis to be fixed on various surfaces, decrease direct contact of fruit with air, and control fruit’s respiration and transpiration rate [73]. Propolis has been applied as a postharvest technique for the local tangerine cultivar Garut. According to physicochemical tests, propolis coating preserved fruit firmness, diameter, and vitamin C levels. In addition, propolis lowered decaying processes 20% longer than the control, with a 10% concentration being best for application [74].

4 Propolis applications in food and feed

4.1 Propolis encapsulation

Encapsulation technology can overcome the limits of environmental sensitivity and low solubility of bioactive substances. Moreover, encapsulation is an appropriate method to control the active substance into polymer chains and, thus, support a continuous release of the effective substances. The customers’ suitability is reduced toward foods containing propolis as an ingredient because of its bitterness and astringency, which provide strong and unpleasant flavors [15]. As a result, the bitter taste of propolis that hinders its applications in the food area could be overcome [8]. Therefore, encapsulation of propolis has been reported as suggesting method for developing active delivery systems that can maintain propolis polyphenols active for an extended period. An encapsulation process effectively prevents the loss of natural active ingredients and keeps them stable until consumed [24].

The main benefit of propolis could be achieved from its extract. Therefore, alcoholic propolis extract has been investigated as a food additive. The encapsulation could be a practical approach to overcoming crude propolis problems. Sodium alginate was used to encapsulate the ethanol extract of propolis. Beads were examined in simulated gastric and intestinal solutions for release properties. The process of microencapsulation involves entrapping materials or compounds inside another so that they are immobilized, produced, and functionalized. Microparticles are made up of two parts, the core material, such as bioactive substances, like propolis, and the shell. One of the most essential features of microcapsules is their ability to release core materials at the right time and place. The encapsulation of ethanolic extract of propolis was planned to improve antifungal efficiency through film or coating growth. Zein is proposed as an encapsulating matrix to keep the ethanolic extract of propolis by utilizing the anti-solvent methodology [75].

Incorporating propolis extracts containing a high percentage of polyphenols into polymeric matrices will improve their stability and bioavailability. Also, this technique may reduce its strong odors and flavors [76]. Furthermore, the encapsulation may enhance the delivery techniques, presenting the prolonged and regulated release of food components. Propolis ethanol extract was encapsulated with biopolymers like gelatin, casein, and chitosan using different techniques. Moreover, the encapsulation properties of these methods are lower than 80%. Other techniques which apply particular circumstances like high temperature may be destructive for effective propolis substances. Ionic gelation, which is cheap and does not require toxic solvents, could be an alternative to encapsulate propolis ethanol extract without using toxic solvents and reach high encapsulation efficacy. This technique has microencapsulated the active substances of ethanol-based propolis extract with alginate matrices. The prepared capsules were presented as a promising method for consuming propolis in a powder form free of alcohol.

Moreover, the capsules will exhibit application in food manufacturing as food constituents. Alginate beads, a biopolymer used as food additives, have been created by the ionic gelation technique with slight alterations. Sodium alginate was mixed with propolis extract to form a homogeneous solution during this technique. As part of the preparation of propolis-alginate beads, the solution was injected into a calcium chloride solution through a syringe. The prepared propolis-alginate beads were dried for ethanol elimination to obtain consumable alcohol-free propolis capsules. The release profile showed that active propolis ingredients could achieve the upper part of the large intestine leading to a growth in the bioavailability of these components [76].

Alginate beads encapsulated jabuticaba peel, and propolis extracts were explored for preparing a novel natural colorant antioxidant additive. The ionotropic gelation conducted the alginate encapsulation by dripping into the calcium chloride solution. The authors demonstrated that encapsulation of anthocyanins (from jabuticaba) and phenolic compounds (from propolis extracts) were sustained onto alginate hydrogel beads. These results suggest the possible applications of these beads as an oral delivery system for supporting natural healthy food/beverage colorants additive [77]. In foods where it is incorporated, propolis can be encapsulated in nanoemulsions to reduce its effect on organoleptic properties. As a result, these systems promote the applications of bio-based materials as nutrients by decreasing their taste impact and improving their antimicrobial properties [78]. Furthermore, emulsions loaded with propolis extract have been utilized to increase their properties for various applications [15, 79, 80].

Dairy proteins were emulsified with polysaccharides to co-encapsulate and protect bioactive nutrients. For example, whey protein isolate/propolis/alginate beads were designed at pH 7.0 for stabilizing α-tocopherol–contained emulsions, the active component of vitamin E.

In a different technique, the propolis can be finely dispersed into polymeric nanoparticles and then sprayed with chitosan microspheres to form solid dispersion matrices to improve its solubility in an aqueous solution [81]. Microencapsulations of gum arabic and maltodextrin were also applied for propolis encapsulation. Approximately 92% of α-tocopherol and 72% of propolis were effectively encapsulated in sunflower oil drops stabilized by whey protein isolate/propolis/alginate matrices [82].

Polysaccharides have been investigated as a promising polymer for drug delivery applications [83,84,85,86]. A mono-pore filter device was used to design chitosan-containing propolis beads, which allow polyphenols to be encapsulated without being heated, shattered, or subjected to toxic solvents. In addition, as a natural antimicrobial delivery system, the beads could limit the expansion of pathogenic/spoilage bacteria in food products [24]. Table 3 demonstrates a valuable study concerning propolis encapsulation.

Table 3 Encapsulation methods used in the protection of the propolis bioactive compounds [R2]. License Number 5446960510218, 13/12/2022, Elsevier
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4.2 Spray-drying

Propolis extract has been spray-dried utilizing gum arabic and octenyl succinic anhydride starch as transporters. This method maintained the antioxidant action of propolis and permitted propolis production as a powder. In cold water, spray-dried propolis dispersed quickly and was stable throughout storage at room temperature. It also had low hygroscopicity and was highly stable. This method has increased the application of propolis in many modern applications, especially in the food sector. Recently, the increasing attention in some food industries to discover bio-additives has expanded the attempts to obtain bioactive substances from biomaterials and improved stable and valuable derivatives. Spray-drying has been presented as a promising technique that may decrease strong taste and aroma. Pharmaceutical and food industries use this method to keep products from environmental circumstances, increase product shelf life, and mask nasty flavors [24]. Spray-dryer was used for efficient propolis encapsulation to create a natural food ingredient with antioxidant activity. Figure 3 shows micrographs of propolis microcapsules [87].

Fig. 3
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Micrographs of propolis microcapsules. A magnified 1800 × ; B magnified 4000 × [87]. License Number 5460740119380, 2/1/2023, Elsevier

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4.3 Preserving food

The probable function of propolis as a food additive has yet to be established, but it has an unpleasant taste that can alter food texture and taste. The addition of 0.1% water extract of propolis on fresh Shibuta (Barbus grypus) fillets through frozen storage expanded the product’s shelf life by around 1 week. In contrast, propolis’s 0.5% water extract caused a considerable shelf life expansion of the Shibuta fillets by around 2 weeks compared to the control sample. Therefore, the water extract of propolis was presented as an accepted preservative for fresh fish products [88]. Propolis extract was proposed as a natural preservative for food in a nanoemulsion, which prevents the degradation and masking of the propolis off-flavor. Despite thermal stress and centrifugation, the nanoemulsion retained all biological properties evaluated for free extracts [89]. According to several researchers, the minimal addition of propolis extract for acceptance sensory of food products is 0.50% [58].

The antimicrobial impact of propolis on foodborne yeasts and its procedure as a biological approach for preserving soft foods against microbial spoilage was examined. The study also highlights the ability of propolis extracts to discourage the growth of checked yeast. The extract of propolis can be used as an antifungal agent against spoiled fruit juice yeasts in small quantities [90].

The efficacy of propolis action for decreasing anthracnose growth on Kent mango fruit and comparing its efficacy to chitosan action was developed. Using propolis alone or in conjunction with other treatments can extend the shelf life of fresh fruits and vegetables [91].

Ethanolic extract of propolis actions at 4.5% preserved the quality of ‘Hindi-Besennara’ mangos during shelf life and was proposed as a natural option to synthetic chemicals. The hydrophobic mixtures of propolis extracts can form a biodegradable semipermeable film on fruit surfaces that may reduce water loss and gas exchange in different products. Propolis has several characteristics that might account for the lower weight loss observed in propolis-treated fruit compared to controls when applied at medium and high rates [92].

4.4 Propolis as a food ingredient

Propolis has been used as a structuring agent to gel pomegranate seed oil, at a 5% concentration, as a limited replacement of the fat phase in chocolate spread [93]. Orange soft drinks flavored with propolis extract were made. Its antioxidant activity, microbiological stability, and color changes were assessed and compared to orangeade holding potassium sorbate. Soft drinks containing propolis extract displayed improved antioxidant activity and phenolic content compared to those including potassium sorbate. The authors suggested that the drinks holding propolis extract, as a bioactive reagent, can stay at a wide temperature range, for more than 16 weeks, without exhibiting quality and microbiological deterioration [94].

Fish sausage is a ready-to-eat/ready-to-cook material made from chopped fish meat. Fish meat is minced and combined with additives, then stuffed into casings, and fried. Using propolis extract to improve the quality of smoked carp (Cyprinus carpio) sausages stored for 9 weeks was studied. Propolis extracts added to carp sausages for 9 weeks significantly decreased the total aerobic mesophilic and psychrophilic bacteria counts compared to control samples. No mold or yeast was identified in any fish sausages during the entire storage period. Aqueous propolis extract positively influenced smoked carp sausage’s chemical and microbiological properties after 9 weeks in the refrigerator [95].

The preparation and description of unique useful nanostructured lipid carriers (NLCs), including β sitosterol, were considered. Transmission electron microscopy results demonstrated spherical particles ranging around 100 nm, proving the probability of these formulations generating valuable foods. In addition, the formation of stable NLCs with long-term physical and oxidative storage stability has been demonstrated utilizing propolis wax and pomegranate seed oil as solid lipid and liquid lipid matrix [6]. Table 4 demonstrates some more recent studies concerning application of propolis as a food ingredient.

Table 4 Propolis as a food ingredient
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4.5 Propolis as a feed ingredient

The total antioxidant capacity and physicochemical properties of meat were assessed next to adding various amounts of propolis in broiler chickens’ diets. Propolis in the chickens’ diet can reduce oxidative compounds without changing their physical and chemical properties [100]. A variety of bio-products are being used in the dietary supplementation of vitamins, fatty acids, carotenoids, immunostimulants, hormones, and adjuvants, with propolis standing out. The use of propolis as a dietary supplement has been recognized in various animal products [101]. Propolis was added to the diets to increase the production performance of different fish types. Propolis is thought to have antimicrobial and antioxidant properties that enhance intestinal health, digestion, absorption, and growth.

Moreover, various minerals and vitamins in the propolis improve digestive cofactors and enzyme activity, enhancing absorption and digestion of nutrients with a subsequent increase in fish weight. Propolis enhances the growing operation and food absorption, decreases microbial activity, and develops the immune response and disease resistance of several grown fish variety. As a result, the water, ethanolic extract, and crude propolis are reported as bio-additives utilized in a low-dose manner.

Fish become healthier and more productive when propolis is applied, giving an excellent ability for utilization in aquaculture production. Lastly, fish consumption may have health benefits [101].

5 Future perspectives, challenges, and limitations

Since propolis is a natural, renewable, and safe product, expanding its use in the future is inevitable and necessary. Therefore, a prosperous and promising future for propolis applications in packaging and food is expected, especially after the many research that allowed and recommended its use. However, the expansion of its use as a food additive is hindered by its bitter taste, which allows it to be used only in small proportions. This problem could be overcome with modern research that starts to provide propolis in an acceptable form of encapsulated product or composites to overcome the unpalatable taste and smell.

6 Conclusion

Propolis has excellent potential for extending the shelf life and improving the quality of several food products. Propolis can prevent negative changes in food’s physical and chemical characteristics to keep food quality. However, the challenges that limit the widespread use of propolis as a food additive are represented in its unpalatable bitter taste and flavor, which negatively affects the food’s sensory qualities, texture, taste, and flavor. As a result, more interest has been paid to using propolis extracts on a product surface or in the form of edible films containing propolis. The incorporation of propolis into polysaccharide-based films enhanced their water vapor barrier and antifungal properties. As a biodegradable packaging material, it can protect the quality of food products, mainly minimally processed fruits and vegetables. Because it contains many bioactive ingredients, propolis has a significant potential to extend the shelf life of a wide range of food products. In addition to being a preservative, it can also be used to prevent adverse physical and chemical changes. As a result of its antioxidant and antimicrobial properties, propolis extract delayed the oxidation and growth of lipids in aqueous smoked carp sausage. Propolis wax could be a novel ingredient in the formulation of lipid nanoparticles. By combining propolis with essential oils, the content of total phenols was increased, and the radical-sequestering function was enhanced; as a result, the antimicrobial properties were enhanced as well. The addition of propolis enhanced the water vapor barrier and antifungal activity of polysaccharides-based film, which can be helpful as a biodegradable packaging material to maintain the quality of food products, particularly for coatings fruits and vegetables.