Application of Natural Functional Additives for Improving Bioactivity and Structure of Biopolymer-Based Films for Food Packaging: A Review

The global trend towards conscious consumption plays an important role in consumer preferences regarding both the composition and quality of food and packaging materials, including sustainable ones. The development of biodegradable active packaging materials could reduce both the negative impact on the environment due to a decrease in the use of oil-based plastics and the amount of synthetic preservatives. This review discusses relevant functional additives for improving the bioactivity of biopolymer-based films. Addition of plant, microbial, animal and organic nanoparticles into bio-based films is discussed. Changes in mechanical, transparency, water and oxygen barrier properties are reviewed. Since microbial and oxidative deterioration are the main causes of food spoilage, antimicrobial and antioxidant properties of natural additives are discussed, including perspective ones for the development of biodegradable active packaging.


Introduction
Food packaging is important for the storage and transportation of products as well as ensuring their safety and quality by protecting from contamination and spoilage [1].Currently, the packaging material market is largely represented by oil-based plastics, the production of which has grown significantly worldwide [2].Plastics have a low biodegradability [3], and agricultural plastic waste reuse and recycling are very low [4].The widespread use of plastic leads to accumulation and adverse effects on the environment and human health [5].Therefore, there is a growing interest in biodegradable packaging materials [6,7].
The global trend towards conscious consumption plays an important role in consumer preferences regarding both the composition and quality of food and packaging materials, including sustainable ones [8][9][10][11].This opens up a new field of activity for researchers: the development of biodegradable active packaging materials with specified functional properties (for example, antimicrobial or antioxidant), which would help to reduce both the negative impact on the environment due to a decrease in the use of oil-based plastics and the amount of synthetic preservatives/antioxidants used in food products that have an adverse effect on human health [12][13][14][15][16].
The development of biodegradable active packaging is a research area of current interest [17,18].Over the past decade, many research projects have been developed within the framework of international funding programs, the most ambitious being Horizon 2020 and Horizon Europe.The projects focused on solving global problems and the topic of adaptation to climate change in the first place.This topic includes dozens of areas in which projects in the field of biopolymer packaging materials have a special place.Selection of component ratios (the ratio of biopolymer, plasticizer and other components) and determination of blend composition for improving structural, mechanical and other characteristics of the packaging material are intensively studied [19][20][21][22][23]. Immobilization of synthetic commercial substances, mixtures and/or mono-additives, such as antioxidants, acids, etc., in packaging matrices could improve biological activity but could be poisonous and hazardous to health [24][25][26].Therefore, natural biologically active substances of microbial, plant and animal origins are in high demand [27][28][29][30].This review also discusses relevant natural functional additives for improving bioactivity of biopolymer-based films.

Biopolymers for Food Packaging
The use of biopolymers has gained popularity in food packaging recently.From the perspective of environmental sustainability, it can be stated that biopolymers serve as environmentally friendly packaging materials [31].Biopolymers are categorized into three groups based on their production method and source of origin: synthesized from bioderived monomers, extracted from biomass and produced by microorganisms [32] (Figure 1).Natural polysaccharides (starch, cellulose, chitosan, etc.) and animal proteins (collagen, gelatin, etc.) are commonly utilized as packaging materials [23] due to their wide availability and the ability to create packaging materials with specific characteristics from them.
based plastics and the amount of synthetic preservatives/antioxidants used in food products that have an adverse effect on human health [12][13][14][15][16].
The development of biodegradable active packaging is a research area of current interest [17,18].Over the past decade, many research projects have been developed within the framework of international funding programs, the most ambitious being Horizon 2020 and Horizon Europe.The projects focused on solving global problems and the topic of adaptation to climate change in the first place.This topic includes dozens of areas in which projects in the field of biopolymer packaging materials have a special place.Selection of component ratios (the ratio of biopolymer, plasticizer and other components) and determination of blend composition for improving structural, mechanical and other characteristics of the packaging material are intensively studied [19][20][21][22][23]. Immobilization of synthetic commercial substances, mixtures and/or mono-additives, such as antioxidants, acids, etc., in packaging matrices could improve biological activity but could be poisonous and hazardous to health [24][25][26].Therefore, natural biologically active substances of microbial, plant and animal origins are in high demand [27][28][29][30].This review also discusses relevant natural functional additives for improving bioactivity of biopolymer-based films.

Biopolymers for Food Packaging
The use of biopolymers has gained popularity in food packaging recently.From the perspective of environmental sustainability, it can be stated that biopolymers serve as environmentally friendly packaging materials [31].Biopolymers are categorized into three groups based on their production method and source of origin: synthesized from bioderived monomers, extracted from biomass and produced by microorganisms [32] (Figure 1).Natural polysaccharides (starch, cellulose, chitosan, etc.) and animal proteins (collagen, gelatin, etc.) are commonly utilized as packaging materials [23] due to their wide availability and the ability to create packaging materials with specific characteristics from them.In the production of biodegradable food packaging, special attention is paid to starch.Starch is the second most abundant organic substance found in nature and serves as the main storage carbohydrate in plants [33].Starch is a good candidate for making biopolymer film due to its structure and crystallinity caused by hydrogen bonds, which help it be easily converted into a thermoplastic material [34].Most published works related to starch focused on wheat, corn, potato and rice starches due to their commercial importance [33].However, it is known that under specially adapted cultivation conditions, microalgae are capable of accumulating starch content up to 40-45% of dry weight [35], which makes them promising candidates for the production of this biopolymer.Quite promising biopolymers are polyhydroxyalkanoates (PHAs), which are biosynthesized by fermentation of sugars and lipids by a wide range of microorganisms [36,37].Besides being biodegradable, biocompatible and renewable, PHAs are known for properties such as high tensile strength, printability, good UV resistance, grease and oil resistance, making them suitable for the food packaging industry [36].
For many years, researchers have been developing active packaging films based on natural biopolymers.However, the competitiveness of these materials still lags behind petroleum-based plastics due to insufficient mechanical properties.These shortcomings can be overcome, and furthermore, functional additives can enhance not only the activity but also the physical and mechanical properties of the films.

Methods to Make Biopolymer Films Bioactive
The incorporation of bioactive compounds into packaging materials enables the development of biopolymer films with antioxidant [38,39], antimicrobial [40][41][42] and barrier properties [43,44], thereby enhancing the safety and quality of food products.Several techniques for integrating natural functional additives into film-forming materials have been documented in the scientific literature [45].Some of these methods include the following: -Incorporation of bioactive substances in the film during the production process by mixing them with a film-forming solution [40,46,47]; -Grafting bioactive compounds onto biopolymer chains [48,49]; -Functionalization by bioactive groups (carboxylic, phenolic, amino groups, etc.) [50], for example, by aminolysis [51]; -Enzyme immobilization [52,53]; -Encapsulation of bioactive compounds with the formation of micro-or nanoparticles.Subsequently, during the film production process, such particles are included in its composition by direct mixing with a film-forming biopolymer solution [44,[54][55][56][57] or by spraying them onto a biopolymer film [43,58].
When incorporating natural functional compounds into biopolymer materials, it is necessary to consider their compatibility as well as the concentration proportions between them [45,59].

Plant Additives
Plants have received greater attention as they contain elevated concentrations of components that possess strong antioxidant activities and can lead to both reduction in nutrient oxidation and microbial spoilage [60,61].Essential oils and plant extracts have become the main alternative to synthetic additives [62].Emulsions, mono-antioxidants or plant wastes are also used as components of biodegradable films for the creation of active packaging.
There are several ways of essential oil production: pressing, fermentation, enflerage or extraction.For industrial production, the method of water steam distillation is most often used [66], especially for extraction from aromatic herbs and spices [67].Hydrodistillation involves the complete immersion of plant raw materials in water followed by boiling and allows isolating compounds insoluble in water [68].Hydrodiffusion extraction is a type of steam distillation, differing only in the way of steam introduction.It is fed from above the plant material.Hydrodiffusion extraction can also be produced under low pressure or vacuum [69].Subcritical water extraction applies water in a liquid state under conditions of a high temperature range (from 100 to 374 • C) at a critical pressure (1-22.1 MPa), which makes it possible to obtain bioactive compounds with minimal destruction and high activity [70].Using liquid carbon dioxide at low temperature and high pressure or hexane allows for higher yield of active components during extraction.However, this method is much more expensive [71].Innovative alternative extraction methods include ohmic hydrodistillation (electric heating), microwave hydrodistillation, solvent-free double-cooled microwave extraction, ultrasonic supercritical carbon dioxide extraction and ultrasonic extraction, which reduce the time and amount of energy consumed as well as improve the quality of the obtained essential oil [72][73][74][75][76][77].
Essential oils are introduced into biopolymer and other films by emulsification or homogenization as any lipophilic substance [89,90].Effectiveness depends on the type and concentration of oil, hydrophobicity, particle size and stability of the emulsion [80].The disadvantages of essential oils are susceptibility of active components to polymerization and oxidation during the shelf life from external (light, temperature, humidity, microbial contamination, etc.) and internal (acidity, water activity of food products, etc.) factors, which can disrupt their functionality [91].Ability to volatilize and break down during the packaging process (thermal effects, high shear rates) are also serious problems [92].
Essential oils affect organoleptics and change the transparency of edible films because they are poorly dispersed in water-based solutions [93,94].Addition of essential oil into the film leads to an increase in thickness, while pores and roughness may be observed [95][96][97].The solubility of films in water and swelling decrease due to an increase in the hydrophobicity of films and the formation of new intermolecular bonds [98].The changes in structural and mechanical parameters almost had a common tendency: a decrease in the tensile strength (TS) and an increase in elongation at break (EAB), which could be linked with uneven distribution of essential oils and insufficient density of the biopolymer matrix [99][100][101][102].Emulsifiers, plasticizers and surfactants that are rich in hydroxyl groups can be added to the film-forming solution (FFS) for better distribution of the components and to avoid the fragility of the film [103,104].Water vapor permeability (WVP) could also be reduced due to the uneven structure of the films [101,105].Color parameters are also changed (e.g., elevated yellowness (B*)), which are usually related to the native color of the essential oils [100,[106][107][108]. Antioxidant properties were also elevated and investigated by various standard methods, such as TEAC, ABTS, FRAP, DPPH and TBARS, to assess the degree of lipid oxidation [95,96,[98][99][100][101][102][103][104]107,108].Antimicrobial activity was also demonstrated against E. coli, S. enterica, B. cereus, S. aureus, S. Typhimurium, L. monocytogenes, P. aeruginosa, Candida albicans and parapsilosis, etc. [95,96,[98][99][100][101][102][103][104]107,108].Gram-negative bacteria were noted to be more resistant to essential oils due to the presence of an external complex and a dense lipopolysaccharide membrane surrounding the cell wall [109].

Emulsions
Emulsions are oil/water systems with surfactants [110].The application of emulsions, microemulsions and nanoemulsions can improve the functional characteristics of the film solution and increase the particle distribution [111].Active nano substances are able to bind with many biological molecules with greater efficiency, thereby increasing antimicrobial and antioxidant properties [112].Low thermal stability is one of the disadvantages of emulsions [104].
Surfactants have hydrophilic and hydrophobic properties and are added to emulsions to increase stability [104].As a component of films with emulsions, surfactants and emulgators can reduce surface tension; improve wettability and adhesion of coating solutions [113]; and reduce moisture loss [114,115].Water resistance and mechanical properties of the films can be improved by including essential oils and hydrophilic surfactants [116,117].However, surfactants can negatively affect the antibacterial activity of the active components [90].
Microemulsions are more transparent, homogeneous and thermodynamically stable [118].They are small droplets ranging in size from 10 to 100 nm and contain additional surfactants and/or solvents [94].The low interfacial tension allows increasing the reactivity of active substances (essential oils) by expanding the surface area and simplifying the preparation of microemulsion without spending a lot of mechanical effort [119].Nanoemulsions consist of particles with a diameter of 0.1 to 100 nm, have the same advantages as microemulsions, can improve physico-chemical properties of films and possess a less-pronounced effect on organoleptic characteristics [110].The advantages of nanoemulsions include higher kinetic stability and a larger surface area ratio, which reduce the release rate [120].Due to the bound moisture in nanoemulsions, they are considered self-preservative antimicrobials [121].However, they have a low stability in an acidic environment and require a large amount of energy for production [11].Pickering emulsions can be used as a stabilizer instead of surfactants [122].Compared with traditional emulsions, a solid layer of microand nanoparticles (silicon dioxide, clay materials, metal and metal oxide nanoparticles, calcium and carbon particles, etc.) is formed between the aqueous and oil phases [123].They are characterized by excellent stability and low toxicity compared to traditional emulsions [122] and could be carriers of essential oils [124] The addition of Pickering emulsion reduces the microstructural uniformity of the films and, consequently, negatively affects the structural and mechanical properties and vapor permeability.It can be solved by crosslinking [125,126].
Micro-, nanoemulsions and Pickering emulsions demonstrated different effects on the film's properties.Thus, addition of microemulsion of cinnamon bark and nanoemulsion of thyme (wild and domestic) increased the thickness of films [94,127].The distribution of film components is different and could lead to both roughness or smoothness [128][129][130].Mostly, moisture content (MC), water solubility (WS), TS, elastic modulus (EM) and WVP were reduced, while changes in EAB varied.Properties of films depended on the influence of hydrophilic and hydrophobic compounds [94].However, the elevation of TS and EAB has also been observed.In a study of nanoemulsion based on rutin introduction into pork gelatin, it is assumed that rutin can act as a crosslinking agent of the film [131].Barrier and mechanical properties of whey protein isolate (WPI) film were improved by Grammosciadium ptrocarpum Bioss.nanoemulsion [130].
Release control, reduction in light transmission and UV resistance are advantages of emulsion implementation [129,131,132].
Antioxidant properties were demonstrated based on ABTS, DPPH and FRAP results, as well as antimicrobial activity against S. aureus, E. coli, L. monocytogenes, S. enterica, etc., and reduction in CFU was also noted.

Extracts
Phenolic compounds are the main components of plant extracts that provide both antioxidant properties and antimicrobial activity [133][134][135][136].A number of factors affect their extraction from plant raw materials, such as solvent, selected method, duration and temperature of extraction and the ratio of extractant: solvent, particle size and affinity to solvent [137][138][139].Water, acetone, ethyl acetate, alcohols (methanol, ethanol, propanol), etc., and their mixtures are the most popular solvents [140].Purification of the crude extract is an important step and includes solid-phase extraction (the most popular method), matrix dispersion solid-phase extraction (allows eluating one or more classes and fractions of compounds) and liquid-solid extraction [141].Classical extraction methods such as conventional extraction (maceration), the Soxlet method, steam-and hydrodistillation are inexpensive but time-consuming processes with low selectivity and high consumption of solvents and energy [142].Modern effective extraction methods have been developed, including extraction with ultrasound, microwave, high pressure, high voltage electrical discharges, impulsive electric fields and supercritical fluids, taking into account profitability, energy conservation and environmental friendliness, as well as applicability on an industrial scale [143].New methods increase the environmental friendliness of extraction by reducing the use of aggressive organic solvents, reduction processing and purification steps and increasing the yield of more thermolabile compounds [138].
Extracts from rosemary, oregano, green tea, cloves, curcumin, oregano, cinnamon, ginger, thyme and citrus fruits (for example, lemon, orange and grapefruit) are the most well studied; among them, oregano and thyme extracts were classified as the most active, while citrus extracts could effectively inhibit the growth of microorganisms [144].The main bioactivity of a plant extract is the antioxidative effect as confirmed by elevation of DPPH, TEAC, etc., values; TBARS, myoglobin oxidation, etc.; and reduction.Several films with plant extracts affected the population of total aerobic counts, yeasts, molds and lactic acid bacteria and demonstrated antimicrobial activity against L. innocua ATCC33090, S. aureus and E. coli.
Distribution and affinity of the active component to the biopolymer affect the surface of the film.There are films with both a rough surface and a smooth one [145][146][147].Addition of plant extract reduced MC and WS [148,149].Swelling index (SI) could be elevated or reduced, depending on the added plant component, which may act as a crosslinker [147,149].A trend of the majority of the incorporated active ingredients is the reduction in TS and elevation of EAB [150].The combination of chitosan and quinoa protein extract enabled the elimination of plasticizers in the film production process.The resulting film exhibited a significant increase in EAB, while its water barrier properties indicated higher hydrophilicity compared to a chitosan film [151].In few cases, an increase in TS and a decrease or slight change in EAB may be noted in the formation of starch and gelatin films, where hydrogen bonds between the active component (phenolic compounds) and biopolymer molecules can be formed [146,152].There were no significant changes in WVP, however, in the study on films from soy concentrate and red pomegranate extract.The WVP decreased since polyphenols bind to the polar groups of protein chains, and they become inaccessible to moisture binding [148].Addition of plant extract also affects optical properties and transparency of films [147,149].
Individual plant compounds are actively used to improve the physico-chemical, structural-mechanical, barrier and organoleptic properties of biopolymer films as well as enrich them in active properties-antimicrobial and antioxidant (Table 1).The film thickness increased with the addition of individual plant compounds, which is explained by the higher content of solids in the packaging material [165,187,189].Interestingly, addition of monolaurin and eugenol to zein film led to the reduction in thickness due to the surfactive properties of monolaurin and good distribution in the FFS.Water contact angle (WCA) was decreased, and that may be related with partial moving of added substances to the surface, which affected the wetting [186].WCA was also reduced in the collagen films with curcumin [189].The surface and structure of the films were different depending on the binding or crosslinking and distribution of the active components.Some films had cracks and voids [165,182,183], while others were smooth and even [186,188].MC was reduced in active films [165,188].The values of WS, SI and WVP varied and depended on the nature of the introduced individual plant compounds and their affinity to biopolymer.Thus, pectin films with apple polyphenols demonstrated an increase in WS and IS, which was associated with the presence of hydrophilic groups in polyphenols.The observed decrease in WVP could correspond to the reduction in the mobility of pectin chains that decreased water vapor passage through the film [184].Sodium alginate films with thymol showed a decrease in WVP, WS and IS due to a two-stage crosslinking of the film with calcium chloride, and crosslinking of caseinate with tannins or collagen with phenolic acids led to the reduction in WVP, WS and IS [165,183,188].The addition of carvacrol in soy protein isolate (SPI) films caused an increase in WVP, presumably due to a decrease in the availability of protein-water interaction; while in starch films, WVP increased slightly [182,187].The values of TS and Young's modulus (YM) decreased with addition of individual plant compounds in films, while EAB increased [186,187].However, crosslinking or strong intermolecular interactions between the polymer and the additive without aggregation of the active compound led to an increase in TS and a slight change in EAB [183,184,189].Weak hydrogen bonds and hydrophobic interactions between collagen and phenolic compounds insufficiently improve TS and EAB [188].The addition of plant compounds affects the color of the films, decreases transparency and elevates the barrier properties against UV and visible spectra [182,183,187].

Waste and By-Products
Peel, pulp, husk, seeds, bark, cake, pomace, etc., are available and constitute about 30-50% of the total plant weight.The waste and by-products contain biologically active substances, including phenolic compounds, flavonoids, anthocyanins, polyphenols, tannins, etc., which may contribute to the antioxidant and antimicrobial potential of the packaging.Taking into account economic issues, increasing the waste implementation and reducing the impact on the environment are quite attractive [198,199].Waste processing to obtain active compounds is carried out by classical extraction using water and organic solvents and their mixtures [200].
Tomatoes are a widespread crop.Tomato pomace consists of seeds, pulp and skin and is often used as feed.It is a rich source of nutrients and biologically active compounds such as carotenoids, sugars and fibers [201,202].Grape seed extracts are rich in flavonoids (catechin and epicatechin, epicatechin-3-O-gallate, procyanidins).Naringenin and hesperidin, ascorbic acid and various organic acids also demonstrate antimicrobial properties.Red grapes are rich in anthocyanins, whereas phenolic compounds dominate in white grapes [203][204][205][206]. Grape pomace, comprising the peel and seeds, is a by-product of wine production and is notably rich in antioxidants, including quercetin and its derivatives [207].The peel and seeds of the pomegranate are an agricultural waste.The inedible part amounts to about 50% of the total fruit weight and is a rich source of phenolic compounds, tannins, anthocyanins and flavonoids [194,206,208].Grapefruit seed extract contains a large number of polyphenolic compounds such as flavonoids, catechins, epicatechin, procyanidins and organic acids (citric, ascorbic), which have antioxidant and antimicrobial activity [209,210].The olive cake is one of the by-products that is generated when processing olive oil and can be a source of pectin, phenolic compounds, carotenoids and other compounds [190,211].Olive mill wastes serve as a source of various bioactive compounds with antioxidant and antimicrobial properties.These wastes contain nutrients, anthocyanins, flavonoids, polysaccharides and phenolic compounds [212].Onion husk represents the main waste component in onion processing (up to 60%) and contains a large number of biologically active phenolic compounds, flavonoids, etc. Purple onion husks contain quercetin and anthocyanins, while yellow ones contain more quercetin and its glycosides [191,[213][214][215][216]. By-products produced during corn harvest (straw, stems, leaves, ears and husks) are a good source of dietary fiber, functional oligosaccharides and phytochemicals.Corn husk has a high cellulose content (30-50%); therefore, its derivatives, such as nanocellulose, can be obtained from it [192,217,218].Licorice is widely used as a natural sweetener in the food industry.The main active components of licorice are glycyrrhizin and its derivatives isolated by aqueous extraction.During the extraction process, waste rich in flavonoids is often discarded [196,219].The nut processing industry produces a large number of by-products (shells, peels, etc.) rich in phenolic compounds [193].Watermelon seeds are a potential source of polyphenols, saponins, alkaloids and flavonoids [195].
Plant waste and by-products can be used for the production of polymer films or as a source of active components of biopolymer films (Table 1).Changes in the mechanical, physical and barrier properties of the films with plant waste are observed mainly due to the interaction of biopolymer with active plant components [191,192].Their addition to films led to an increase in thickness [190,191,197].It was reported that the density of the films decreased, probably due to the better particle distribution in the film matrix.Channels and cavities correlated with an increase in corn husk fiber [192].Hydrogen bonds between the SPI and the waste extract probably led to the formation of small pores and the roughness on the surface of the film [196].WS and MC are also reduced with addition of plant waste [191,193,197].An increase in SI and MC of whey protein with melanin films is associated with a greater availability of hydroxyl groups due to the interaction of the main components [195].Elevation in WVP of sodium alginate film with red onion husk extract and gelatin film with tomato pomace oil extract could be linked with an increase in the free volume of the matrix [191,197].Films with a homogeneous structure and good dispersion of the components, on the contrary, had a significant decrease in WVP.Changes in the film structure could lead to WVP variability [190,192,196].Increase in TS and slight changes in EAB could be linked with the formation of a dense intermolecular structure between chitosan and microparticles of olive waste, and with an increase in concentration, the structure was destabilized [190].In low methyl pectin with corn husk fibers at ratio 5.0 g/100 g of pectin, an increase in TS was also noted [192].The films based on whey proteins had strong hydrogen bonds between melanin and the polymer matrix, which also affected the reduction in the water vapor transmission rate (WVTR) and WCA [195].Gelatin films with licorice residue extract also had a stable structure with a strong interaction between flavonoids and protein molecules [196].The addition of pecan nutshell or hazelnut skin extracts partially improved the resistance to water by decreasing the solubility and increasing the WCA, improving the UV light-blocking properties in starch films [193].The addition of plant waste and by-products affects the color of the films, decreases transparency and elevates the barrier properties against UV and visible spectra [190][191][192][193][195][196][197].
Plant waste and by-products mainly contain phenolic compounds, which are more effective against oxidative processes, confirmed by elevation of DPPH, FRAP, ABTS, radical scavenging activity, etc., of films [190][191][192][193][195][196][197]220].Biopolymer films with by-products have great potential, as issues of the waste disposal and improvement of the characteristics of film materials are being resolved.

Microbial Biologically Active Substances
Microbial antimicrobial substances can act as natural preservatives preventing or minimizing microbiological spoilage of food products [221].Various Gram-positive and Gram-negative bacteria produce bacteriocins [222].Bacteriocins are low-molecular-weight (rarely more than 10 kDa) thermally stable active peptides that exhibit pronounced antimicrobial activity against various types of microorganisms [223].According to APD3, among 3146 natural antimicrobial peptides, 383 of them are bacteriocins [224].Bacteriocins are usually named depending on the genus of producing strain.Thus, lacticin and nisin are produced by Lactococcus spp., enterocin by Enterococcus spp., pediocin by Pediococcus spp., leucocin by Leuconostoc spp., etc. [225].
Among Gram-positive microorganisms, lactic acid bacteria (LAB) attract special attention and represent a diverse and health-promoting group of bacteria [226].LAB have been used for canning and fermenting of various food products [227,228].The use of LAB strains and/or their metabolites as bioconservants contributes to the effective suppression of bacterial growth [229].Nisin, pediocin, lacticin, enterocin and bacteriocin-like inhibitory substances (BLISs) are LAB metabolites [229].LAB and their metabolites are of particular importance and classified as GRAS (generally recognized as safe) [225].LAB bacteriocins are generally widely used as food preservatives and exhibit inhibitory activity against closely related and unrelated microorganisms [230].
Bacteriocins possess antimicrobial activity against pathogenic and spoilage bacteria, which justifies their biotechnological potential.Broad-spectrum bacteriocins with ability to inhibit the growth of pathogenic microorganisms belonging to another genus, such as Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, etc., are of great interest [231].Bacteriocins often have synergies with other treatments and can be used as components of hurdle technologies to extend food shelf life [228].The particular interest of bacteriocin implementation in various food industries is explained by their lack of odor and color and, therefore, not affecting the organoleptic characteristics of food products [232].In addition, bacteriocins can be easily cleaved by proteolytic enzymes such as trypsin and pepsin, which makes them safe for human consumption [230].Based on chemical structure, molecular weight, biochemical properties, spectrum of antimicrobial activity and mechanism of antimicrobial action, bacteriocins are divided into three main classes: heat-stable bacteriocins containing lanthionine (class I); small, heat-stable bacteriocins not containing lanthionine (class II); and large heal-labile antimicrobial proteins (class III) [226].
Class I bacteriocins include several groups: lantibiotics, lipolantins, thiopeptides, botromycins, linear azole-containing peptides, sactibiotics (sactipeptides), lasso peptides, cyclic bacteriocins with a «head-to-tail» connection and glycocins [233].Lantibiotics are the most studied group.Lantibiotics are post-translationally modified low molecular weight antimicrobial peptides (less than 5 kDa) containing lanthionine and/or methyllanthionine residues [234].Based on the molecular structure, three types of lantibiotics can be distinguished-AI, AII and B corresponding to bacteriocins of linear, combined and globular conformation.AI-type lantibiotics include nisin, epilancin 15X and microbisporicin [233].Nisin is the most popular bacteriocin with GRAS status and approved for use as a food additive.Nisin has been widely used as a food preservative for more than sixty years [12].Nisin is a thermally stable polypeptide with molecular weight of 2-4 kDa produced by certain Lactococcus lactis strains and exhibited antimicrobial activity against a wide range of Gram-positive microorganisms, including Enterococcus, Staphylococcus, B. cereus, Lactobacillus, Leuconostoc, L. monocytogenes, C. botulinum, C. sporogenes, Micrococcus and Pediococcus.However, nisin demonstrates a weak inhibitory effect or its complete absence against Gram-negative bacteria, yeast and molds; therefore, it is advisable to use it with preservatives based on sorbic acid [235,236].The low effectiveness of nisin against Gram-negative microorganisms is associated with the inability of nisin to penetrate the outer lipopolysaccharide (LPS) membrane of the bacterial cell [237].At the same time, a number of studies have shown that nisin is an inhibitor of both vegetative cells and spores [238,239].Since nisin is non-toxic, thermally stable and odorless, it is commercially used as preservative in various food products, including dairy and meat products, eggs, vegetables, fish, beverages and cereal-based products [240,241].
Class II bacteriocins are heat-stable, lanthionine-free peptides with a molecular weight of less than 10 kDa and divided into three subclasses-IIa, IIb and IIc [231].Class IIa includes pediocin, sakacins, leucocin, carnobacteriocins, etc., and are called pediocin-like peptides with conserved N-terminal sequence Tyr-Gly-Asn-Gly-Val [228].This subclass is of great interest due to its high antimicrobial activity against Listeria monocytogenes [242].Pediocin PA-1 is the most widely studied bacteriocin of subclass IIa [243] and produced by Pediococcus spp.[242].Pediocin is a cationic molecule with a low molecular weight (2.7-10.0kDa) [244] with a wide spectrum of action, especially against L. monocytogenes, and is used as a food preservative [243,245].Pediocin can be produced by several bacteria of this genus, the main of which are Pediococcus pentosaceus and Pediococcus acidilactici [242].It also was reported that pediocin could be also produced by P. damnosus, P. cellicola, P. parvulus, P. stilesii, P. Inopinatus, P. claussenii and P. Ethanolidurans [244].Pediocin has thermal stability and also retains activity in a wide range of temperatures and pH [246].Enterocin is produced by Enterococcus faecium and demonstrates high antimicrobial activity [245].Enterococcus faecalis (strains L2B21K3 и L3A21K6) produce bacteriocins with high antimicrobial activity against L. monocytogenes [247,248].Cultivation media with enterocin remain active against L. monocytogenes for 90 days [247].Strain E. avium DSMZ17511 demonstrated high antimicrobial activity against L. monocytogenes [249].
The studies on the use of bacteriocins as antimicrobial agents included in the biodegradable films have been published, especially concerning nisin with GRAS status and a wellstudied pediocin.The inclusion of bacteriocins in the packaging film has an advantage over dipping or spraying, which lead to the reduction in antimicrobial activity as a result of reaction with food ingredients or a decrease in their concentration due to migration into food products [12].
Films with nisin and pediocin demonstrated an inhibitory effect against pathogenic microorganisms L. innocua, L. monocytogenes, etc. [250][251][252][253].However, some authors reported that an increase in the concentration of nisin did not lead to an increase in antimicrobial activity against microorganisms [254,255].There was no inhibitory effect of nisin against Gram-negative bacteria, such as E. coli, S. typhimurium and P. aeruginosa [254,256,257].A decrease in TS and YM in tapioca starch films was seen probably caused by a change in the structural modification of the starch in the presence of nisin.Antimicrobials may disrupt the association of biopolymer chains, reducing the number of inter-chain hydrogen bonds.High WVP is associated with the hydrophilic nature of polysaccharides used in films [258].In some cases, EAB was elevated in gelatin films with nisin that could be explained by the presence of sodium chloride (NaCl), nisin filler, which may reduce the electrostatic repulsion between molecules and lead to a denser microstructure of the film matrix [255].Improved mechanical properties of starch-chitosan films with the inclusion of nisin could be linked with transverse bonds formed between nisin and chitosan [259].The addition of pediocin in a moderate concentration contributed to changes in mechanical properties of cellulose films, which indicates the possible interaction of pediocin with the cellulose matrix, which has become more rigid [252,253].
The introduction of bacteriocins into edible films leads to moderate changes in their mechanical and barrier characteristics and elicits a pronounced antimicrobial effect (Table 2).Changes in mechanical properties may be related to the interaction between chains of antimicrobial agents that can easily penetrate the film matrix.Increased and then decreased the load at break.An increase in thickness in a dose-dependent manner.
Antimicrobial activity against L. innocua and L. monocytogenes.

Animal Biologically Active Substances
Active packaging with antimicrobial properties is one of the most promising [263].Antimicrobial packaging can be prepared by incorporating synthetic or natural antimicrobial agents into films or by direct coating.Currently, plant and microbial substances with antimicrobial properties are most widely used as active components for inclusion in films [264][265][266][267]. Animal antimicrobial substances have been less studied.However, they have pronounced antimicrobial potential [268] and may become good candidates for active packaging.Many of animal antimicrobial compounds belong to enzymes, glycoproteins and antimicrobial peptides [268,269].

Enzymes
Antimicrobial enzymes are widespread in nature and play a crucial role in protecting organisms from a bacterial attack [270].They have the ability to directly attack microorganisms, inhibit biofilm formation, destroy biofilm and/or catalyze reactions that lead to the formation of antimicrobial compounds [271].Antimicrobial enzymes are used in certain technologies.For example, liquids with antimicrobial enzymes are used to clean surfaces [272].Enzymes can be incorporated into polymer materials or cover them to prevent microbial colonization.The compositions may contain one or more enzymes or enzymes in combination with other antimicrobial agents [271].
Lysozyme was the first enzyme whose primary amino acid sequence was determined and whose structure was determined using X-ray crystallography [273].Although lysozyme is traditionally associated with bird eggs, especially domestic chickens, it is widespread in nature and found in many sources, including some vegetables, insects, plants and fungi [274][275][276].Lysozyme was detected in human colostrum [277], mammalian milk, saliva, mucus, blood, tears [21], macrophages, leukocytes, monocytes and neutrophilic granulocytes [273].Lysozyme plays an important role in immune response to infections and inflammation [278].Lysozyme derived from chicken egg protein (EC 3.2.1.17)has a bacteriostatic and bactericidal activity, mainly against Gram-positive bacteria.The mechanism of action is the cleavage of the β-1,4 bond between N-acetylmuramic acid and N-acetylglucosamine peptidoglycan chains of the bacterial cell wall [279].Lysozyme has no activity against Gram-negative bacteria due to the presence of an outer membrane surrounding peptidoglycan chains [280].However, Gram-negative bacteria can become sensitive to lysozyme in the presence of detergents and chelators such as ethylenediaminetetraacetic acid (EDTA), which can destabilize the outer protective membranes, making peptidoglycan molecules available for the action of the enzyme [279].Lysozyme also exhibits antioxidant activity [281].Lysozyme-C derived from chicken eggs was legalized as a food enzyme for use in food preservation [273].Lysozyme is actively used to control the growth of microorganisms in foods such as cheese and wine and can be used as a preservative in other food systems [282].Lysozyme serves as a good model of an ideal food preservative in many ways: it is an innate component of the human immune system and, therefore, should have low toxicity [277,282]; acts catalytically and can be used in low concentrations in food [283]; specific to bacterial peptidoglycan, does not react with human tissues, and also has certain properties of resistance to heat and low pH, etc. [284].Lysozyme use in food packaging materials can extend the shelf life of non-sterile or minimally processed foods by preventing a microorganism's growth [284].It has been shown that poly-(l-glutamic acid) nanofilms with egg lysozyme inhibit the Microcccocus luteus growth [285].Edible pectin antimicrobial film technology capable of controlling the release of lysozymes is studied.The presence of pectinases enhances the release of lysozymes, which confirms the expediency of using the developed edible antimicrobial film to protect food from lysozyme-sensitive microorganisms, especially those that produce pectinolytic enzymes [279].Lysozyme addition to the film-forming solution contributed to the antimicrobial activity of films and affected the mechanical properties.Thus, lysozyme addition to low methoxyl (LM) pectin led to an increase in YM and a slight decrease in EAB [279], while addition to jackfruit seed starch strongly affected YM, EAB, TS and WVP [280] in a dose-dependent manner.
Lactoperoxidase (LP) is a hemoprotein presented in milk, tears and saliva [286] and is the most common enzyme in cow's milk [287].The peroxidase activity associated with cow's milk was first demonstrated by Arnold in 1881, and a protein called lactoperoxidase was isolated by Theorell and Akeson in 1943 [273].The interaction of lactoperoxidasethiocyanate-hydrogen peroxide forms the so-called lactoperoxidase system (LPS), in which hydrogen peroxide serves as a substrate for LP during the oxidation of thiocyanate (SCN−) and iodide ions, which leads to the formation of highly reactive oxidants [286].The association of lactoperoxidase with microbial growth inhibition was first demonstrated by Wright and Trammer (1958) [288], whereas the characterization of the entire LP system, including enzymes and substrates, was carried out later [289].In addition, the LP system has hexokinase and glyceraldehyde-3-phosphate dehydrogenase activities [290], which can contribute to the antimicrobial action of the system [273].The LP system has the ability to suppress bacteria, fungi, parasites and viruses and is thus considered a natural broad-spectrum antimicrobial agent [291].It has been shown that during pasteurization, milk loses about 75% of LP activity, while purified LP becomes unstable after 15 min [273].Thermal denaturation of LP in milk, whey, permeate and buffer begins at about 70 • C, and the concentration of calcium ions affects the thermal sensitivity of LP [292].The thermal stability of lactoperoxidase is lower in an acidic environment (pH 5.3) and may be associated with the release of calcium from the molecule [293].LP is deactivated during storage at pH 3 with partial denaturation at pH < 4, while at pH values up to 10, enzyme deactivation does not occur [293,294].The adsorption of LP on certain surfaces can cause a significant decrease in activity [273].The use of the LP system as a natural preservative in food products, in particular in dairy, has increased significantly after the introduction of industrial processes for the isolation of LP from milk and whey [293].The LP system's addition to biodegradable films enhanced antimicrobial activity and did not significantly affect barrier properties, but can affect the mechanical ones.Thus, LPS with combination with chitosan extended the shelf life of cooled fish [295], while incorporation in defatted soybean meal-based (DSM) films led to antimicrobial activity against S. typhimurium [296].Shokri et al. investigated the effectiveness of the LP system in combination with whey protein to create edible food coatings, and the shelf life was increased to at least 16 days in the presence of LP system [297].The enzyme LP may be a good candidate for the inclusion into biopolymer films and coatings to extend the shelf life of food products [294][295][296][297][298][299][300].

Glycoproteins
Glycoproteins are proteins in which carbohydrates (glycans) are covalently bonded to proteins [301].The proportion of glycans ranges from two to thirty percent or ranges from fifty to sixty percent or more of the total mass of the molecule [302].These molecules have many properties such as biodegradability, biocompatibility, non-toxicity, antimicrobial and adsorption properties; therefore, they have a wide range of applications.
Lactoferrin (LF) is also called lactotransferrin or lactosiderophilin [268].LF is an ironbinding bioactive glycoprotein of the transferrin family, which contributes to the control of iron in biological fluids.LF is found mainly in milk, on the surface of mucous membranes (for example, in intestinal epithelial cells) and mammalian exocrine secretions such as saliva, tears and seminal fluid, as well as in secondary granules (vesicles) of polymorphonuclear neutrophils or lymphocytes [303,304].Human and pig's milk contain significantly higher concentrations of lactoferrin (almost ten times) than cow's milk [273,305].Nevertheless, the highest concentrations of LF are present in the colostrum of cattle; at the same time, an increase can also be observed in milk after a mastitis infection [273].
LF plays an important role in many physiological mechanisms, such as the adsorption of metal ions in the intestinal tract [306], promoting digestion and assimilation of micronutrients and macronutrients from milk [307], suppression of myelopoiesis [308], protection of the intestinal flora of young animals from enteropathogenic bacteria [309], protection from mastitis [310], immunoregulatory function (i.e., contribution to the pre-immune innate protection of mammals) and opsonic activity [273].LF has antioxidant properties and demonstrates a wide antimicrobial spectrum, including antibacterial, antifungal, antiprotozoal, antiviral and antitumor properties [268,311], and LF addition in films could affect barrier and mechanical properties (Table 3).Did not exhibit significant inhibitory effects against E. coli and L. monocytogenes. [312] 1 mL of LF (in PBS)/10 mg bacterial cellulose (BC)

BC nanofibers
The WVP was not altered.
A decrease in YM and TS, a slight decrease in EAB.
The shelf life of coated shrimp samples was extended by three days when stored at 4 • C due to a reduction in free fatty acid content, total volatile base nitrogen, lipid oxidation and carbonyl content.
Bacterial cellulose films with bovine LF significantly inhibit E. coli and S. aureus growth, but are characterized by a decrease in mechanical properties [313].Combination of LF and lysozyme in cellulose-based food packaging [316] demonstrated wider antimicrobial activity.
Ovotransferrin (OTF, also called conalbumin) is an iron-binding monomeric glycoprotein that makes up at least 10-12% of the total solids of egg whites [319].OTF isolation and purification can be performed using solvent fractionation and chromatographic methods (ion exchange chromatography or metal affinity chromatography) [320].OTF has a high affinity for iron [321]; therefore, stoichiometric balance of iron affects the OTF [273].Saturation of OTF with iron reduces its effectiveness against many Gram-negative bacteria [322].However, OTF remains effective against Gram-positive bacteria, including lysozyme-resistant strains, at 30-39.5 • C, regardless of the presence or absence of iron [323].Alkaline pH and elevated temperature (~40 • C) enhance the antimicrobial activity of OTF [323].On the other hand, OTF is thermosensitive, and 80% of the activity is lost when heated to 70-79 • C for 3 min or 60 • C for 5 min [324].OTF is considered to have mainly a bacteriostatic activity, although there is evidence of a biocidal effect against a wide range of bacteria such as E. coli, Klebsiella spp., Proteus spp., Pseudomonas spp.and S. aureus [273].It is reported that OTF prolongs the lag-phase and reduces the growth rate of many Gram-positive and less sensitive Gram-negative microorganisms [320].Among Gram-positive bacteria, Bacillus spp.and micrococci are the most sensitive to OTF [273].An inhibitory effect has also been observed against Candida spp.[325].Despite the negative effect of iron saturation on the OTF antimicrobial activity, it is reported that the complex of OTF with other metal cations increases its antimicrobial effectiveness [326].Biopolymeric film made of κ-carrageenan with OTF could extend the shelf life of chilled chicken breast (Table 3); however, the addition of EDTA was recommended to enhance the antimicrobial effect [314].OTF addition to gelatin demonstrated poor mechanical characteristics, but with pronounced antimicrobial activity against E. coli, F. psychrophilum, S. putrefaciens and P. florescens [315].
Avidin is another glycoprotein isolated from the protein of various bird eggs.Avidin is a positively charged glycoprotein with a mass of 66 kDa and can also be found in egg jelly of invertebrates [327].Discovery of the antibacterial molecule streptavidin produced by Streptomyces spp.(avidin analog 60 kDa) showed a similar primary structure compared to avidin and confirmed suspicions that avidin has antimicrobial properties [273].Although the antimicrobial activity of avidin has not been established, it has been suggested that the compound is involved in antimicrobial responses based on streptavidin production by Streptomyces during the formation of an antibiotic system and supported by the initiation of avidin production at a site of injured tissue in chickens [328].It is assumed that the production of avidin and its secretion by macrophages are induced during inflammation and cellular damage and as such may constitute a host protection factor against bacterial and viral infection [329].Miller and Tausig (1964) showed an increased amount of avidin in chicken tissues after intraperitoneal and intravenous administration of E. coli that confirmed the opinion that avidin is aimed at combating microbial infection [273,330].It has been hypothesized that due to the high affinity of avidin for biotin, it can act as an antimicrobial agent, making biotin inaccessible to microorganisms that need it [331].It has been shown that avidin inhibits in vitro yeast and bacterial growth [327].

Histones and Antimicrobial Peptides as Potential Agents for Inclusion into Biopolymer Matrices
Histones or histone-derived fragments have antimicrobial activity in vertebrates, from fish to humans.The antimicrobial activity of histones was first demonstrated in 1958 for histones A and B purified from calf thymus and exhibited activity against various Gram-positive and Gram-negative bacteria [332].
Fish antimicrobial histone proteins have been found in skin mucus or liver tissue: H2B-like proteins in catfish skin [333], H2A in trout skin [334] and H1 in Atlantic salmon liver [335].Pat et al. found high levels of histones H2A, H2B, H3 and H4 in the hemocytes of the Pacific white shrimp Litopenaeus vannamei and demonstrated their activity against Micrococcus luteus [332].
A mixture of histones (H1, H2A, H2B, H3, H4 and H5) extracted and purified from chicken erythrocytes has antimicrobial activity against various Gram-negative and Grampositive planktonic bacteria and Gram-positive bacterial biofilms [336].Jodoin and Hincke reported that histone H5 isolated from chicken erythrocytes has a powerful broad-spectrum antimicrobial effect against Gram-positive and Gram-negative planktonic bacteria (MIC range: from 1.9 ± 1.8 to 4.9 ± 1.5 micrograms/mL), including vancomycin-resistant Enterococcus and methicillin-resistant S. aureus and anti-biofilm activity against L. monocytogenes и P. aeruginosa biofilms [337].Histones can be isolated from chromatin by acid extraction [338].Due to the pronounced antimicrobial activity, histones could be attractive as antimicrobial agents in active food packaging.Nevertheless, the issues of their use as active components of food packaging need to be experimentally confirmed.
Antimicrobial peptides (AMPs) are identified in almost all species, from bacteria to humans, and have a wide range of antimicrobial activity against bacteria, fungi, viruses and eukaryotic parasites [339,340].AMPs form an important part of the "innate" resistance of the host organism, acting as the first line of defense against infection.It is important to note that AMPs are considered to have a completely different mechanism of action from clinically used antimicrobial agents [341].The main mechanisms responsible for the antimicrobial activity of AMPs are associated with the permeability of target membranes and the subsequent leakage of cells, inhibition of RNA, DNA and protein synthesis as well as a decrease in cell viability [289].There are studies on the inclusion of bacterial and plant AMPs into biopolymer films for active packaging [245,342], but few studies concerning animal ones.
According to APD3, among 2463 AMPs from animals, 373 from mammals, 619 from arthropods and 146 from fish were annotated [224].Animal AMPs are numerous and include such classes as defensins, cathelicidins, hepcidins, histatins and lactoferricins (derived from lactoferrin) [343].Defensins and cathelicidins are one of the most widely expressed in mammals [344,345].Synthesis of recombinant AMPs with a known or bioinformatically calculated sequence for their further use is quite popular compared to their extraction from native animal tissues.These technologies are in high demand, but obtaining the recombinant mammalian AMP presents some difficulties.The studies on new AMPs are more widespread than the investigation of the effective AMP isolation, e.g., from insects [346] and invertebrates [347].The issues of native peptides' extraction, in particular AMPs, are quite complex, while isolation and practical application of protein hydrolysates are more studied.Protein hydrolysates are studied as food preservatives and include porcine blood protein hydrolysate [348], gelatin hydrolysate from blacktip shark skin [349] and fish collagen hydrolysate [350].Integration of protein hydrolysates into edible films and coatings was used to suppress the growth of microorganisms [351] (Table 3).Polypeptide fraction is used without purifying specific peptides, and the activity of these fractions can be not only antimicrobial, but also antioxidant, antifungal, etc.
The issue of using extracted and purified endogenous animal AMPs as active components of biopolymer packaging materials is not well discussed.However, some AMPs may be promising candidates for inclusion into the biopolymer matrix.Thus, pleurocidin from the skin of winter flounder Pleuronectes americanus [273] demonstrated activity against Gram-positive S. aureus, L. alimentarius и L. monocytogenes and Gram-negative E. coli, S. typhimurium и Vibrio spp. as well as against yeast and mold fungi.This broad-spectrum activity points to the potential of this antimicrobial peptide as a food preservative [268,352].There are quite a lot of studies on insect AMPs.Thus, cecropins B and P1 showed elevated inhibitory activity against E. coli, which is found in milk, meat and vegetables [346].Peptide Hf-1 isolated from the larvae of Musca domestica (Diptera:Muscidae) demonstrated bactericidal activity against E. coli, P. aeruginosa, S. typhimurium, S. dysenteriae, S. aureus and B. subtilis [353].Jelleine-1 from royal jelly of honey bees has a strong antimicro-bial activity against food-borne pathogen L. monocytogenes by both pore formation and effect on DNA; the formation of biofilms was also significantly reduced [354].Persulcatusin is an antimicrobial peptide of the Ixodes persulcatus that showed the highest activity against methicillin-resistant S. aureus without visible damage to the mammalian and human cells [355].Thus, pronounced antimicrobial activity made AMPs potential agents for the inclusion into the biopolymer matrices for the development of promising active packaging materials to slow food spoilage and increase their safety and shelf life.

Organic Nanoparticles
Various organic, inorganic and combined nanoparticles (NPs) are used in the development of effective food packaging [356].The inorganic NPs are the most variable and include transition and alkaline earth metals, non-metals, metal oxides, nanoclay and graphene oxide and are commonly used in food packaging materials [357].Biopolymer organic nanoparticles/nanobeads are easy to prepare and highly stabile in biological fluids and during storage [358].Organic nanoparticles are different in types: micelles, dendrimers, liposomes, nanogels, polymeric NPs and layered biopolymer [359].The most used organic NPs in food packaging are nanocellulose (NC), chitosan NPs and starch NPs; nanofibers, nanoplatelets, nanotubes and nanowires can also be used [357].
NC can be isolated from plants or synthesized by bacteria.NC produced from plants can be classified into two types: cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs), while NC produced by many species of bacteria is the bacterial nanocellulose (BNC) [360,361].NC lacks antimicrobial and bioactive properties [362]; therefore, NC is usually used as a reinforcement agent for bio-based films [363].The most common strategy used for biopolymer composite synthesis based on BNC is in situ technique, which involves the addition of materials (e.g., sodium alginate, carboxymethylcellulose (CMC), gelatin, agar, pectin, starch) to the culture medium at the beginning of the BNC production process [364].Chitosan can be synthesized into NPs (ChNPs) via many methods such as ionic gelation, reverse emulsion and polyelectrolyte complexation [365].One of the most investigated properties of chitosan is its antimicrobial effect embracing from food to agriculture applications [366].In addition, ChNPs can enhance mechanical strength of biodegradable plastics [367] (Table 4).Starch nanoparticles (StNPs) demonstrated strong reinforcing effects, a positive impact on barrier packaging and could be prepared by hydrolysis, emulsion, ultrasonication, self-assembly, nanoprecipitation, etc. [365].Starch itself does not have antibacterial [368] properties and could demonstrate antioxidant action due to loading various phenolic compounds [369,370].Protein-based NPs can be natural or synthesized and obtained via natural self-assembly, chemical or physical [365,371,372].Protein-based NPs are used in food packaging to enhance the strength and barrier properties such as water barrier properties [356].However, due to unique properties, protein-based NPs are excellent carriers of bioactive substances as a component of active packaging [373].Encapsulation into lipid-based, polymeric-based and nanoclay-based NPs can protect and control the release of active compounds and can enhance the performance of biopolymeric matrices [374].Therefore, organic NPs are often used not only as reinforcing agents, but as a carrier of antioxidants, antimicrobials, inorganic NPs, etc., for active packaging development [66,[374][375][376][377][378].

Conclusions
Polymer packaging allows to increase the shelf life of products and to reduce or eliminate exposure to light and heat, additional contamination and excessive development of microorganisms, thereby reducing product oxidation and microbial spoilage.The growing concern about the environmental pollution associated with the widespread use of plastic packaging requires the search of alternative renewable resources that are biodegradable for the sustainable production of biopolymers as a packaging material.Biofilms are mainly based on hydrophilic polysaccharide and protein polymers, which may include lipid components to increase hydrophobicity.In addition to the edible/biodegradable packaging development, research in this area has led to the creation of active and intelligent packaging.Active packaging provides reduction in microbial, oxidative and enzymatic spoilage, possible contamination, weight loss and changes in color and integrity of products during storage.The use of active additives in the packaging provides a number of advantages compared to direct introduction into food-the use of a lower concentration of active substances, controlled release and a decrease in stages of technological processing of products.Addition of plant, microbial, animal and organic nanoparticles into bio-based films is extremely relevant due to safety and direct activity.

Table 1 .
Application of plant additives in food biodegradable packaging.
gelatin of pork skin/sorbitol (2 g:30 g/100 g of gelatin)Less uniform structure.An increase in TS and EAB.A decrease in WS, WVP, EM and glow.Changes in color.

Table 2 .
Application of bacteriocins in food biodegradable packaging.

Table 3 .
Animal biologically active agents used in food biodegradable packaging.

Table 4 .
Organic nanoparticles used in food packaging.