Food packaging is any wrapper whose function is to protect food from physical, chemical, and biological contamination and preserve its quality [15]. Physical contamination is any external material (e.g., bumps or pieces of glass, plastic, and wood) that are is part of the food and that is normally associated with unhygienic conditions during the preparation, production, storage, and distribution of food products. In contrast, chemical contamination can occur from the addition of food additives (e.g., flavors, colors, and sweeteners) or other chemicals (e.g., antibiotics, sanitizers, pesticides, and lubricants) during processing, food preparation, and storage. Biological contamination is related to any micro-organisms (e.g., Salmonella sp., Clostridium sp., and Escherichia coli) or harmful fauna (e.g., rats, mice, and cockroaches) that produce toxins (e.g., aflatoxins, citrinin, and alternariol) or cause consumer illness [16,17].

The increase in the demand for food in the market stimulated the innovation of food packaging to improve the characteristics of traditional and active packaging that were used until a few years ago. Subsequently, packaging with new characteristics was conceptualized, or so-called intelligent packaging. This type of packaging is made up of a system influenced by the physicochemical properties, temperature, exposure time, or enzymatic reactions of foods that monitor, generate, and display the information [21]. Intelligent packaging uses chemical sensors or biosensors to monitor food quality, including ripeness, freshness, temperature, oxygen levels, moisture, or other gases [18].

Active packaging is more studied than intelligent packaging since there are many extracts and essential oils extracted from natural sources that have an antioxidant or antimicrobial nature and can be added as a biological additive [22]. Nevertheless, active packaging and intelligent packaging are not mutually exclusive since both can work synergistically together [23]. There are even authors who contradict the idea of using the terms intelligent packaging and smart packaging as synonyms because they establish that smart packaging is active–intelligent packaging in which the characteristics of both are added [18].

Biodegradable films are solid matrices with a thickness of less than 0.3 mm [24] which are formed with biopolymer material [25,26] using casting, extrusion, or electrospinning techniques [27]. Biodegradable films are considered active packaging as their protective function includes the addition of bioactive compounds [2]. Biodegradable films present greater benefits than conventional packaging since in addition to meeting the main objectives of food passive packaging (i.e., protection against mechanical, chemical, and biological damage), they can also reduce UV light interaction [28], control the absorption of gases (e.g., oxygen, ethylene, carbon dioxide, and water vapor) [28,29], and control the release of bioactive components (e.g., antioxidants, antimicrobials, and flavors) [30,31,32]. These objectives create benefits, including the reduction of lipid oxidation and the increase in the nutritional value of food and its shelf life [33,34].

The formation of biodegradable films is carried out due to the interaction between polymers (i.e., polysaccharides, lipids, and proteins), and polysaccharides are the most widely used biopolymers for biodegradable films due to their accessibility [35]. The main natural sources of polysaccharides are plants (e.g., cellulose, starch, and pectin), animals (e.g., chitin, chitosan, and hyaluronic acid), algae (e.g., alginate, agar, and carrageenan), fungi (e.g., glucans and pullans), and bacteria (e.g., dextran, xanthan, and gellan) [35]. According to the Scopus database, more than 50% of biodegradable film reports are based on plant polysaccharides, with cellulose being the most widely used polymer [36]. This is justifiable because it is the most abundant polysaccharide in nature, it is inexpensive, and it is obtained using simple methods, such as alkaline hydrolysis [37]. Chitosan and chitin (ca. 30%) are the most used animal polysaccharides for the generation of biodegradable films [36], and their extraction is based on the demineralization, deproteination, and distillation of residues from the shells of crustaceans [38]. These animal polysaccharides are appreciated due to their antimicrobial activity caused by their cationic characteristics [35]. In contrast, algae polysaccharides represent around 11% of the natural polymers reported for the generation of biodegradable films [36]. Alginate stands out because its extraction is traditionally carried out from brown algae using hydrolysis acid–alkaline [39]. Less than 10% of the rest of the studies report biodegradable films based on fungi and bacteria [36]. This is because bacteria and fungi need strictly controlled conditions of temperature, substrate, and exposure times so that the production yield is high [40]. However, the production of a polysaccharide by fermentation or by culture cannot be compared with the extraction yield of a polysaccharide from a plant or an animal.

Additives, such as plasticizers, crosslinkers, or bioactive components, improve their characteristics and properties [25,26]. In the compilation made by Suderman et al. [41], it was stipulated that the most used plasticizers in biodegradable films are glycerol, sorbitol, xylitol, and fructose because they influence the microstructure and consequently improve mechanical (e.g., brittleness and flexibility), physicochemical (e.g., solubility), thermal (e.g., thermal decomposition), and barrier (e.g., gas absorption) properties. However, the interaction between polymer and plasticizer depends on the nature of both. For example, Sanyang et al. [42] concluded that adding plasticizers (i.e., glycerol and sorbitol) to the formulation of sugar palm starch films reduced brittleness and water absorption and increased solubility and moisture. Kaewprachu [43] reported higher elongation, moisture, and water vapor permeability in fish protein films by adding plasticizers (i.e., glycerol, sorbitol, and polyethylene glycol). The use of lipids in the formulation of biodegradable films has been carried out only in composite films, including some lipids (e.g., oils, waxes, and resins) mixed with polysaccharides and/or proteins, because their hydrophobic nature hinders the formation of cross-linking [44]. For example, Hassan et al. [45] formulated sugar palm starch/chitosan films with olive oil and noted that the lipid acted as a plasticizer that improved the elasticity and brittleness of the biodegradable films and stabilized the thermal and barrier properties. Additionally, Da Silva E Silva et al. [46] noted an increase in mechanical strength and a decrease in water vapor permeability when buriti oil was added to fish gelatin films.

Biodegradable films can use crosslinking agents, such as stimuli (e.g., pH and electrical charges) or components (e.g., ions and enzymes) to generate physical, chemical, or enzymatic changes and improve the interaction between polymeric components [47,48,49,50,51,52]. Chitosan is an acetylated polysaccharide that necessarily needs a cross-linking agent (an acid such as acetic, formic, or lactic acid) [53] to acidify its medium and increase its protonation [20] so it can interact with other molecules and eventually form biodegradable gels and films [54]. In amino polysaccharides or proteins, it is common to use genipin as a crosslinking agent because it produces nucleophilic reactions between amino and carboxylic groups in a neutral-acid medium [55] so they can generate biodegradable films due to intermolecular interactions [56]. Other protein cross-linking agents are enzymes (e.g., transglutaminases) because they can catalyze isopeptide bonds and improve the three-dimensional network of biodegradable films [57,58]. In contrast, the use of radioactive waves (e.g., electron beam, gamma radiation, and ultraviolet light) in starches can cause hydrolysis and linear restructuring of the chains, which then cause an increase in the hydrogen bonds and the crystallinity of the film [59,60].

In addition, biodegradable films may contain bioactive substances or components (molecules that can affect health) [61] extracted from natural sources (e.g., plant extracts, natural oils, or essential oils) which have an antimicrobial [62], antifungal [63], antioxidant [64], or probiotic effect [65]. However, regardless of the additives, polysaccharides (e.g., starches, gums, celluloses, agars, and pectins) are the most widely used polymers in the formulation of biodegradable films due to their hydrophilic nature, accessibility (i.e., sources and costs), and characteristics (e.g., non-toxic, biodegradable, and bioactive) [35].

Foods are susceptible to spoilage due to physical, enzymatic, chemical, or microbiological effects, which accelerate maturation and senescence and consequently modify product quality [66]. Food quality is based on sensory characteristics and its nutritional and functional properties which allow their acceptability. For direct consumers, sensory characteristics, such as color, appearance, texture, shape, size, odor, and taste demarcate the degree of product acceptability [67]. Therefore, packaging is important as it protects and maintains food quality from post-harvest until it reaches the consumer.