From Fields to Films: Exploring Starch from Agriculture Raw Materials for Biopolymers in Sustainable Food Packaging

Abstract

In the wake of escalating global concerns over the environmental impact of plastic pollution, there has been an unprecedented call for sustainable alternatives. The food-packaging industry, responsible for a staggering 40% of global plastic consumption, faces mounting challenges driven by environmental degradation and concerns about fossil fuel depletion. Motivated by these challenges, there is a growing interest in reducing reliance on traditional packaging and exploring eco-friendly solutions derived from renewable resources. Eco-efficient packaging, specifically derived from agricultural raw materials, emerges as a promising solution that aligns with ecological, economic, and social sustainability principles. Starch, abundant and versatile, emerges as a frontrunner among agricultural raw materials for biopolymers. Its inherent properties, including low cost, availability, biodegradability, and biocompatibility, make it a compelling choice. Starch-based bioplastics, with their potential to replace synthetic primary packaging materials, have gained traction due to their satisfactory mechanical and barrier properties. This review delves into the realm of starch-based films and coatings for food applications. It explores fundamental properties, advantages, and limitations, offering insights into potential improvements through various treatments or additive combinations. As technological advances drive the popularity of biodegradable starch-based packaging, this review aims to contribute to the ongoing discourse, providing a comprehensive overview and paving the way for more functional and widely applicable products in the ever-evolving landscape of sustainable packaging.

1. Introduction

In an era marked by heightened awareness of the detrimental effects of plastic pollution on our planet, there has been an unprecedented global call for action. The pervasive presence of plastics in our oceans, landfills, and ecosystems has catalyzed a collective recognition of the urgent need for sustainable alternatives. Since their discovery in the early 20th century, plastics have dominated different packaging sectors due to their versatility, ease of processing, low cost, lightweight nature, and satisfactory visual, mechanical, and chemical properties [1,2]. Until 2015, the global annual production of petroleum-based materials exceeded the mark of 300 million tons [3], reflecting an annual growth rate of 5% over recent decades [4]. Recent data indicate that in 2019, plastic production surged to approximately 370 million tons [2].

As highlighted by Estevez-Areco et al. [5], the food-packaging industry is responsible for consuming approximately 40% of the world’s plastic production. The widespread use of these materials, coupled with concerns about the limited availability of fossil fuels and the ecological issues in terrestrial and marine environments arising from the non-biodegradability of synthetic polymers [6,7], has spurred a growing interest in reducing consumption of traditional and disposable packaging. Concurrently, there is a concerted effort to develop alternative products from renewable and natural resources that can degrade more quickly after disposal. In this context, eco-efficient packaging stands out, produced using materials that respect the ecological, economic, and social premises of sustainability, with a focus on polymers derived from biomass [8,9]. Apart from being sourced from inexhaustible supplies, these materials appear to be capable of ensuring the quality of both fresh and processed food products [10,11,12].

There is a growing demand for the development of food packaging materials using an agricultural product matrix that involves utilizing raw materials derived from agricultural sources to create sustainable and eco-friendly alternatives to traditional packaging. The agricultural matrix, which encompasses various crops and their by-products, can be transformed into packaging materials through innovative processes. This approach aligns with the growing global commitment to reducing reliance on non-biodegradable plastics and mitigating environmental impact.

Biodegradable plastics are engineered to degrade over time through biological processes, yielding compounds that microorganisms can metabolize [13]. The adoption of bio-based materials in packaging presents promising alternatives to traditional petroleum-based plastics, supporting sustainability goals and minimizing environmental impact. Starch-based polymers, polylactic acid (PLA), cellulose-based films, polyhydroxyalkanoates (PHA), chitosan, and protein-based materials offer diverse options for creating biodegradable, compostable, and renewable packaging solutions [14,15].

Leveraging renewable resources and biodegradable properties, these materials provide versatility and functionality while combating plastic pollution. Embracing bio-based packaging represents a significant opportunity to transition to a more sustainable future. Particularly, biopolymers sourced from agricultural resources offer sustainable alternatives to conventional plastics, addressing environmental concerns related to food waste and non-biodegradable packaging materials [16]. These materials can be sourced from various crops and plants, presenting eco-friendly options for a range of applications. Polysaccharides, such as cellulose [17], pectin [18], and proteins, such as soy, gluten, and corn protein [19], are some examples of based biopolymers that are explored for applications in food packaging. The use of these agricultural raw materials for biopolymer production aligns with the growing demand for sustainable and renewable alternatives to conventional plastics. It also promotes circular economy principles by utilizing by-products and waste from agricultural processes. Cristofoli et al. [19] reviewed the advances in food packaging production from agri-food waste and by-products. This study critically examined the methods employed in processing and producing such biomaterials on a laboratory scale. The findings of this study underscore the need for a critical re-evaluation of current laboratory-scale methods for biomaterial production from food waste and by-products. Researchers continue to explore and innovate with these materials to enhance their properties and expand their range of applications.

Among many agricultural raw materials for obtaining biopolymers, starch emerges because of its cost, availability, high extraction yield, edibility, nutritional value, biodegradability, and biocompatibility [20]. Abundant in nature, it can be found in seeds, roots, and tubers of agricultural products, as well as in agroindustry by-products and residues, in order to promote the circular economy and contribute effectively to the bioeconomy [21]. Starch-based bioplastics are considered promising alternatives to wrap (films) or cover directly (coatings) different foodstuffs’ surfaces, replacing the synthetic primary packaging materials and guaranteeing food’s quality and safety due to the satisfactory mechanical and barrier properties (i.e., gases, UV light, moisture, and microorganisms) reached by some modifications of the starch matrix and/or combinations with other substances [22]. Hence, Dufresne and Castaño [23] emphasized that starch-based films and coatings are advantageous because of the possibility of processing in equipment used in conventional plastics industries, highlighting the competitiveness of new products in the packaging market.

Technological advances and the popularity of biodegradable starch-based packaging in recent years have encouraged the search for new matrices and methodologies for more functional, higher-quality, and widely applied products [24]. As such, this review aims to summarize and provide some insights into starch-based films and coatings for food applications, presenting general fundamental properties, advantages, and limitations, as well as possibilities to improve the characteristics of films and coatings by recurring to different treatments or adding substances.

2. Starch as a Biodegradable Matrix for Bioplastics

Starch is highlighted as the most widely used plant-based polysaccharide in the production of packaging for foodstuffs. In addition to the low cost because of the expanded offer, the benefits of its use are associated with high extraction yield, edibility, nutritional value, biodegradability, and biocompatibility [22]. Also, the possibility of converting to thermoplastic materials and processing them in equipment used in conventional plastic industries emphasizes the competitiveness of starch-based packaging on the market [23,25], so approximately 50% of the bioplastics currently commercialized are derived from it [26].

2.1. Starch Physicochemical Characteristics

Native starch is synthesized from glucose molecules produced by photosynthesis and accumulates in different organelles and tissues of roots, tubers, cereals, vegetables, and fruits. The structure, morphology, size, and chemical composition of starch granules depend on the botanical species [27,28]. They consist of amylose (20–25%) and amylopectin (75–80%), which are polymers of D-glucopyranose that are structurally and chemically distinct, as illustrated in Figure 1.

Amylose has a predominant linear structure with a molecular size ranging from 20 to 800 kg/mol. The main chain is formed by D-glucopyranose units connected by α-1,4 glycosidic bonds, and its hydrophobic helix allows a complex formation with phospholipids and free fatty acids. Amylopectin is highly branched, so its molecular weight is higher, ranging from 5000 to 30,000 kg/mol [28]. It differs from amylose by having α-1,6 glycosidic bonds at branch points [29].

The fractions of amylose and amylopectin vary according to the starch source listed in

Table 1. Amylose and amylopectin contents in different starch sources (reproduced from [26]).

Starch Source	Amylose (%)	Amylopectin (%)
Arrowroot	20.5	79.5
Banana	17.0	83.0
Cassava	18.6	81.4
Corn	28.0	72.0
Potato	17.8	82.2
Rice	35.0	65.0
Tapioca	16.7	83.3
Wheat	20.0	80.0

(reproduced from [26]), and these differences allow us to infer about their potential for plastic packaging formation and characteristics.

Because of the branched structure, amylopectin has greater solubility, so the greater the fraction of amylopectin, the greater the stability of starch gel in an aqueous medium as well as the film flexibility. Otherwise, a substantial fraction of amylose in starch can form more resistant and firmer films [12] with a reduced tendency to swell and solubilize [27,30] due to a higher content of hydrophobic molecules.

In terms of molecular organization, starch granules are composed of amorphous and crystalline regions in alternating layers formed by an association of amylose with large branches of amylopectin molecules and by linked short-branched amylopectin molecule species, respectively [27]. The crystallinity of starch granules generally ranges from 20 to 45%, depending on the ratio of these two polymers and, consequently, on the source and age of the starch [31].

Some molecular characteristics of the granules (i.e., composition, structure, and crystallinity) have a huge influence on starch properties. When isolated and purified, starch is characterized by a white color, does not have specific odors or flavors, and is insoluble in cold water or alcohol [26] due to the hydrogen bonds that hold the molecular structure. However, when heated to 65–90 °C in the presence of excess water or other solvents able to form hydrogen bonding (i.e., liquid ammonia, formamide, formic acid, chloroacetic acid, and dimethyl sulfoxide), starch granules soak up, promoting a break in the amylopectin matrix and a leaching of amylose through the intergranular space to the aqueous medium. Subsequently, the semicrystalline structure is disrupted, causing the swelling, loss of birefringence and molecular order, and solubilization of starch granules until an irreversible stage known as gelatinization [28,32]. In addition to the molecular characteristics of starch granules, gelatinization is dependent on processing conditions such as water availability, time, and temperature [27]. Alongside that, the higher gelatinization temperature observed in starches indicates a heightened ability to endure swelling and rupture [33].

Rheological properties also affect the functionality of starch granules and are related to the stability of starch products. The major parameters of starch rheology when considering commercial applications like bioplastic production are paste viscosity, texture, transparency, shear strength, and the tendency of retrogradation [27]. In general, the viscosity of starch suspensions increases as the granules swell. After gelatinization, with a decrease in the system temperature, amylose molecules and intermediate materials suspended in the media reassociate, forming crystalline zones, typical of the retrogradation phenomenon. The higher the retrogradation, the higher the gel opacity [12].

2.2. Starch Extraction and Transformation into Biodegradable Plastics

As a ubiquitous carbohydrate abundantly present in various agricultural products, starch offers a compelling raw material for the development of eco-friendly polymers. The next topic delves into the intricate process of starch extraction and its subsequent transformation into biodegradable plastics, emphasizing its potential as a sustainable solution to mitigate the ecological impact of conventional plastics.

2.2.1. Starch Isolation from the Matrix

Isolating starch from other chemical components does not involve specialized processes or complex techniques. The methods used for starch extraction vary according to the botanical origin of the matrix and have to be suitable in terms of starch purity, properties, and yield.

According to Wani et al. [34] and Farshi et al. [32], starch extraction methods are classified into wet milling and dry milling. The wet process is generally applied on a laboratory scale to obtain high-purity starch and involves milling or grating, fiber separation, starch suspension in water, separation by decantation or centrifugation, and flour drying. In roots and tubers, the simplicity of the process is justified by the tissue structure of the raw materials and their low content of lipids and proteins. On the other hand, some types of starch require additional efforts to be isolated, especially when they are associated with other macromolecules such as proteins and fibers (as in fruits, cereals, and legumes). In these cases, the most commonly used techniques for starch extraction apply chemicals (i.e., citric acid and ethyl alcohol) or enzymes [35,36,37].

At an industrial level, commercial starch extraction is achieved by the conjugated use of mills and an air classification system to separate starch from the protein matrix. It has been reported that this technique decreases the gelatinization temperature and increases the apparent amylose content, cold water solubility, and transparency. Alongside that, the purity of starch obtained is lower than that achieved by wet milling due to a lower capacity to remove most of the protein impurities [34].

2.2.2. Starch-Based Bioplastics Manufacturing Methods

Starch has a great film-forming ability, especially because of its amylose fraction. Generally, starch bioplastics have desirable features for food packaging. They are strong, isotropic, odorless, tasteless, and colorless [38,39].

The transformation of starch into biodegradable plastics can be carried out in two different ways, namely casting (wet way) and melt or thermoplastic processing (dry way) [28,29,30,31,32,33,34,35,36,37,38,39,40,41]. Both techniques breakdown the semi-crystalline structure of the granules and use plasticizers in order to increase the flexibility of bioplastics by reducing the retrogradation of starch over time.

The casting method, represented in Figure 2a, is characterized by the gelatinization of amylose and amylopectin in excess of water (>90% w/w), plasticizing agents (i.e., polyols, low molecular weight sugars, urea, or oils extracted from oilseeds), and heating the solution to temperatures higher than the gelatinization temperature of the starch (between 65 °C and 90 °C), with subsequent degassing and drying of the formed filmogenic suspension [28,42]. Despite being a low-cost method, its application on an industrial scale is rarely used because of the low yields [43].

However, casting offers advantages such as simplicity, low equipment costs, and versatility in producing thin films and coatings. Solution casting, for example, allows for precise control over film thickness and composition, making it suitable for applications requiring uniformity and transparency. Furthermore, it was noted that films produced via the wet process exhibit lower mechanical resistance, higher moisture content, increased water vapor permeability, greater water solubility, and enhanced hydrophilicity compared to those manufactured through the dry process [44].

In contrast to casting, the dry process is considered more efficient, rendering it suitable for large-scale processing. However, a notable disadvantage is the high equipment costs [45,46]. The melt processing uses the application of pressure, shear forces, and heating of the starch solution and plasticizers at high temperatures (above the glass transition temperature of the molecule) to break down amylose and amylopectin. Melt casting, is well-suited for bulk production of thicker materials like sheets and containers. After controlled drying, the bioplastic obtained has rheological properties comparable to conventional thermoplastics, which makes it possible to use extrusion, thermoforming, and injection molding technologies, as illustrated in Figure 2b,c, available on the market [1,29].

Thermoplastic processing methods like extrusion, injection molding, and compression molding offer advantages in terms of scalability, efficiency, and versatility in shaping complex geometries.

Extrusion, for instance, enables continuous and versatile production, making it ideal for large-scale manufacturing of starch-based products with the possibility to incorporate biocompounds [47]. Injection molding is suitable for high-volume production of intricate parts with tight tolerances and can be used in conjunction with the extrusion method. Additionally, compression molding is commonly used due to its low energy requirement and rapid formation [48]. In the dry process, the twin-screw extruder emerges as the most commonly utilized type of extrusion for starch-based plastics. Additionally, compression molding has been widely explored to produce bilayer films involving the incorporation of at least one layer of starch, according to Siqueira et al. [45].

The selection of the most suitable method depends on factors such as desired product characteristics, production volume, cost considerations, and processing requirements. It has to be highlighted that all processes are directly affected by the combination of temperature and time, especially during starch gelatinization. It is reported in the literature that these parameters may vary with amylose and amylopectin chain length, but there is no temperature–time binomial defined for specific starch sources, although a complete disruption of hydrogen bonds (which maintains the crystalline structure of starch) is essential to determining the physical, mechanical, and barrier attributes of bioplastics [33]. Thakur et al. [49] quote that as the developed bioplastics are often used in the preservation of foodstuffs, only water, ethanol, or a combination of these solvents is suitable for the solubilization of starch. In addition, all components of the film-forming solution must be safe for the consumer’s health, including food quality regulations such as the “Generally Regarded As Safe” (GRAS) statute and the regulations applicable to the food product in question [50].

3. Starch-Based Films and Coatings as Food Packaging

As the primary packaging for food, starch-based bioplastics are applied to maintain or improve the quality and safety of the packaged foodstuffs during storage. Like regular packaging materials, as water and gas barriers, they may prevent the dehydration of fresh products and the loss of crispness in dry products, control the senescence of fruits and vegetables, reduce the oxidation of some food components, delay the loss of aroma and flavors, as well as carrier compounds such as antioxidants and antimicrobials [28,40,51,52].

Depending on their thickness, bioplastics can be used to wrap or coat food, as illustrated in Figure 3. The primary methods for producing starch-based films include casting, which involves a wet process, as well as molding and extrusion, which are dry processes [45], wherein all the materials undergo spatial rearrangement to form a gel structure [32].

Casting is a wet process that involves solubilization, casting, and drying. Firstly, excess water is boiled along with starch to achieve gelatinization. Subsequently, the film is allowed to dry, either through natural evaporation or by using drying equipment (30–40 °C) under relative controlled humidity (30–85%), and a clear starch film is formed after it has been cast onto flat dishes [45,53]. According to Liu et al. [46], the wet process is primarily utilized at the laboratory scale due to its time-consuming nature.

Films with a maximum thickness of 200 μm are applied as wraps for different food products [29], and very thin films are used as coatings, being dried and dispersed directly on the food surface by immersion or spraying [42,54]. Particularly in the latter, the properties of the film-forming solution must be defined considering the methods used for its coverage and the characteristics of the food’s surface to be covered. For good adherence and uniformity of application, food products coated by immersion must be submerged in solutions with high viscosity; however, if the dispersion is carried out by spraying, the solutions must be low viscous. In addition, fruits and vegetables with a smooth surface need solutions with low surface tension, while those with rough and irregular surfaces need formulations enriched in plasticizers to guarantee the coating’s integrity [40].

Most of the research carried out in the scope of obtaining starch-based films and coatings focuses on the use of conventional sources such as corn, rice, potatoes, beans, and cassava, but there is a notable trend towards the use of new matrices, namely some starches that are not predominant in the diet or extracted from agro-industrial by-products (

Table 2. Films and coatings developed by casting from unconventional starch sources.

Starch Source	Plasticizer	Gelatinization Conditions	Processing Conditions	Bioplastic Characteristics	Reference
Pine nuts (Araucaria angustifolia) seeds	Glycerol	80 °C and 30 min	Room temperature and 24 h	Edible film	[55]
Babassu (Attalea spp.) mesocarp	Glycerol	81 °C and 30 min	35 °C and 10 h	Active film 1	[36]
Yam (Dioscorea spp.)	Glycerol	185 °C	40 °C and 48 h 50 °C, 3 h + 70 °C, and 1 h	Edible film	[56,57]
Mango (Mangifera indica L.) seeds	Glycerol + sorbitol	NR	Immersion and 30 s	Edible coating	[58]
	Glycerol	90–95 °C and 30 min	23 ± 2 °C and 48 h	Active film 1	[12]
	Glycerol + sorbitol	90 °C	45 °C and overnight	Edible film	[59]
Amazon turmeric (Curcuma longa L.)	Glycerol	95 °C and 15 min	40 °C and 8 h	Active film 1	[60]
Arrowroot (Maranta arundinacea)	Glycerol	85 ± 2 °C and 5 min	25 ± 5 °C and 24 h	Active film 1	[61]
Jackfruit (Artocarpus heterophyllus L.)	Glycerol	70 °C	Immersion and 1 min	Edible coating	[62]
Loquat (Eriobotrya japonica) seeds	Sorbitol	95 °C	25 °C and 10 h	Edible film	[63]
Ulluco (Ullucus tuberosus Caldas)	Glycerol	95 °C	8 °C and 168 h	Edible film	[64]
Job’s tears (Coix lachryma-jobi L.)	Sorbitol	80 °C and 20 min	25 °C and 16 h	Active film 1	[65]
Pumpkin (Cucurbita máxima)	Glycerol	95 °C and 30 min	60 °C and 24 h	Edible film	[20]
Quinoa (Chenopodium quinoa) seeds	Glycerol	95 °C and 30 min	60 °C and 24 h	Edible film

NR = Not reported; ¹ Films with antioxidant properties.

), combined with active compounds (i.e., antioxidants) with beneficial properties for human health and the preservation of food quality.

3.1. Starch-Based Bioplastics Physicochemical Properties

Biodegradation is affected by several factors, such as polymer morphology and structure. Concerning the former, amorphous regions within polymers are more susceptible to degradation once they are more far apart from each other, compared to the crystalline regions. As for the latter factor, polymer structure plays a pivotal role, particularly through the presence of hydrolysable linkages. Those polymers that have both hydrophilic and hydrophobic regions are more prone to degradation than those containing only one of these regions [66].

In general, starch films are known for their hydrophilic nature, satisfactory organoleptic properties, and absence of toxicity [11,67]. However, its functionality and potential uses are closely related to the starch source and its amylose and amylopectin fractions, crystallinity, gelatinization temperature, and the type and concentration of the plasticizer used in its manufacture [68,69]. It is a consensus that the higher the amylose content, the greater the gelling capacity of the polymer and, consequently, the formation of films and coatings. Basiak et al. [70] evaluated the effects of different sources of starch on the physicochemical properties of edible films. It was observed that solutions with high concentrations of amylose generate films with good mechanical and barrier properties, which favors their application in foods with high water activity, such as cheeses, fruits, and vegetables. It is also concluded also that the granulometry of starch crystals and the morphology of the developed films are directly related to their thickness, permeability, opacity, and mechanical properties.

Hydrogen bonds are responsible for the low mobility of starch molecules and, consequently, for the typical lower flexibility of these bioplastics when compared to conventional synthetic plastics [8]. This limitation can be fixed through the addition of plasticizers and organic substances incorporated in different concentrations into the starch gel to improve the film’s mechanical properties.

Muscat et al. [71] observed the behavior of films made from starches with high and low levels of amylose, using glycerol and xylitol in different concentrations and gelatinizing the starch under different temperatures. Films with a lower concentration of plasticizers (15%, d.b.) showed a brittle appearance even when the filmogenic solution was drying. However, high concentrations of xylitol (30 and 40%, d.b.) enhanced the film’s phase separation. Regarding mechanical properties, amylose-rich starch films showed greater tensile strength and less elasticity than the others. Also, the higher the concentration of plasticizers applied to both films, the lower the tensile strength and the greater the elongation at break. So, the films prepared from the combination of glycerol + 20% xylitol (d.b.) provided the best water vapor barrier properties and reasonable mechanical properties.

Other issues to overcome are water solubility and the retrogradation phenomenon in bioplastics. To obtain more stable materials, many reinforcement compounds can simply be added to the starch matrix, and/or the starch can undergo a series of physical, chemical, enzymatic, and genetic modifications [11,69,72].

In the analysis of various starch types, parameters such as structure, morphology, and degree of crystallinity are studied by Dome et al. [73].

However, it is essential to establish a direct correlation between these physicochemical properties and the performance of the corresponding bio-based products. Understanding how variations in starch structure, morphology, and crystallinity impact factors such as mechanical strength, thermal stability, barrier properties, and biodegradability is crucial for optimizing the formulation and production of bio-based materials. Therefore, future research efforts should focus on elucidating these relationships to facilitate the development of high-performance bio-based products with tailored properties.

3.2. Functionalization of Starch-Based Bioplastics

The functionality and compatibility of starch-based materials can be improved, eliminating the flaws found in native starches and turning them into excellent raw materials for making films and coatings for food. The incorporation of various compounds into the starch matrix facilitates the modification of physicochemical properties in starch products. This encourages interactions that positively impact their plastic behavior, particularly in terms of gelatinization, rheology, mechanical properties [68], and unique features.

As it requires improvements in physical, mechanical, and barrier properties, the native starch used in making edible films and coatings is generally modified through physical and chemical techniques and/or combined with several substances (i.e., lipids, other polysaccharides and biopolymers, natural fibers, reinforcing agents, and functional compounds).

3.2.1. Changing Properties of Native Starch for More Films and Coatings

From the modification of starch molecules by physical and chemical methods, the low mechanical resistance, thermal decomposition, the great tendency to retrogradation, and the strong hydrophilic behavior are worked on, improving the performance of these bioplastics and matching them to the non-biodegradable plastics.

Physical Modifications Induced in Starch

Most physical modification techniques are related to technologies used by the industry for food preservation. They can combine temperature, humidity, pressure, shear, and irradiation to obtain native starch particles with lower granulometry and greater solubility in water at room temperature. As they do not use chemical or biological agents, they are environmentally friendly, non-toxic [27,74], and do not interfere with the starch’s biodegradability [75].

Among the most widespread methods, the use of ultrasound stands out because of its good performance, short reaction time, and moderate conditions of use [35]. In addition to microstructural changes in the granules’ morphology and crystallinity [76], the high-frequency electrical vibrations can reduce the viscosity of the starch paste and its gelling capacity, while the thermal stability and retrogradation are improved [11]. Zhu [77] mentioned that through ultrasound, it is possible to improve the dispersion of starch for the bioplastic films’ production and also benefit their transparency, structure, and resistance to humidity. Brodnjak et al. [78] evaluated the properties of rice starch films pre-treated with ultrasound and found that electrical vibrations triggered positive effects on morphology, tensile strength, elongation, water vapor permeability, and film solubility. The modification of sweet potato starch resulted in films with similar characteristics, as studied by Liu et al. [79].

It should be pointed out that the modifications observed depend directly on the frequency of the electric waves, the temperature, the process time, and the properties of the native starch in modification, related to its botanical source and the concentration of the work suspension [27,35,80].

Physical methods involving energy irradiation are highlighted by significant improvements in terms of potential cost and reduced toxicity. Microwave irradiation is also able to alter the functionality of native starches. By controlling humidity and temperature and through the penetration of heat, the rearrangement of amylaceous molecules is facilitated. Therefore, variations in gelatinization, solubility, swelling capacity, and rheological behavior are promoted according to the characteristics of the matrix used and the processing conditions applied [81]. In general, starches pre-treated by microwave irradiation tend to be potential raw materials to make coatings and to form opaque gels [11]. Zhong et al. [82] applied microwave irradiation to corn starch and obtained films with good tensile strength, low elongation, low water solubility, and reduced transparency.

Gamma irradiation has also been applied to the modification of biomass polymers. It is characterized by inducing chemical reactions of macromolecules’ degradation with their subsequent oxidation in the presence of atmospheric O₂, leading to the formation of carbonyl and carboxyl derivatives [11,83]. The functional groups formed by chemical reactions induced in macromolecules give modified starch a lower molecular weight, reduced viscosity, and greater solubility, among other satisfactory film-making properties. Cieśla et al. [84] and Cieśla et al. [85] confirmed in their studies that films made with potato starch treated with gamma irradiation showed better hydrophobic and mechanical resistance properties, in addition to greater elongation. Similar results have been reported by Li et al. [86] for corn starch films and by Akhavan et al. [87] in composite films of potato starch, PVA, and ZnO.

Some physical modification of native starches occurs through hydrothermal processes, emphasizing heat–moisture treatment (HMT) and annealing. The first method consists of heating the starch granules at high temperatures (84–140 °C) and in low moisture conditions (10–40%) for a variable period [88]. The observed changes involve increases in gelatinization temperature, thermal stability, and tensile strength, as well as a reduction in swelling capacity and solubility. Furthermore, Shah et al. [11] mention that HMT contributes to a greater film-forming capacity. Some recent studies have been carried out by Majzoobi et al. [89] with rice starch, by Rafiq et al. [90] with horse chestnut starch, and by Indrianti et al. [91] with sweet potato starch. All authors found better mechanical properties and greater hydrophobicity in the developed films.

Similarly to the HMT, annealing is associated with a physical reorganization of the starch granules and their partial gelatinization in excess of water [27]. Like other heat treatments, the effects observed by the modification involve a reduction in swelling capacity and solubility, although the water absorption capacity is variable and affects the film formation process [11].

Starch Modifications by Chemical Treatments

In some cases, it is difficult to develop functional and thermostable starches from physical modification, so chemical treatments must be used. Chemical modifications perform significant changes in the structure of D-glucopyranose units by the insertion of functional groups in the polymer chain.

Guarás et al. [75] mention that these reactions are conditioned by factors such as the composition and structure of the starch granule (i.e., amylose and amylopectin ratio and its molecular structure, presence of lipids and phospholipids, morphology, etc.), the type of reagent used, and the conditions of the reaction medium. In addition, the effects observed on the morphological, thermal, mechanical, and rheological properties of starch depend on the method or combination of methods used for the modification and the degree of modification. It is common for multiple modification methods to be used successively to improve the texture, formation, and adhesion power of films and their hydrophobicity [92].

Cross-linking is the most widespread method for reducing the water absorption and solubility of native starch. Through the formation of ethers or esters between the hydroxyl groups of the linear and branched chains, the starch granules are stabilized [8,93], and with the increase in molecular mass, the polymer becomes more resistant to water and mechanical forces. Shah et al. [11] reported that starches with a higher degree of cross-linking exhibit a greater water absorption capacity while maintaining their viscosity and texture.

Citric acid has also been used as a cross-linking agent in recent studies because of its multi-carboxylic structure and antimicrobial effect in edible and bioactive films [94]. Gutiérrez et al. [95] reported that the films of cassava and yam starch modified by cross-linking with sodium trimetaphosphate (STMP) showed greater tensile strength and greater elongation when compared to films made with native starch from the same tubers. In addition, Yıldırım-Yalçın et al. [96] used STMP and citric acid to modify corn starch and form edible films, verifying significant reductions in films permeability to water vapor and O₂, water solubility, swelling capacity, and elongation with the usage of both reagents. Satisfactory properties were also observed by Dai et al. [97] in edible films of cross-linked cassava starch.

Despite the technological advantages, cross-linking reactions can hinder or even prevent starch gelatinization, which limits its use in the formation of films and coatings. To overcome this limitation, it is common to associate this method with other physical or chemical modification techniques [11].

The substitution of hydroxyl polar radicals in native starches by functional groups of interest involves the formation of ethers or esters from the reaction with different chemical agents. In general, substituted starches are less susceptible to retrogradation and crystallization, have lower gelatinization temperatures, and have a greater water absorption capacity. In addition, the gels formed by the gelatinization of substituted starch granules are more transparent but less firm [92]. However, the flexibility, mechanical strength, and barrier properties of the films can be improved depending on the treatment applied. Shaikh et al. [98] evaluated the effects of acetylation (with acetic anhydride) and hydroxypropylation (with propylene oxide) of millet starch to make edible films and found that hydroxypropylated starch films had greater transparency, water solubility, and flexibility, while those developed with acetylated starch showed a significant reduction in hydrophilic character. A similar behavior was observed by Colivet and Carvalho [99] in films of acetylated cassava starch, which presented a greater contact angle and less water vapor permeability than those made with native cassava starch, highlighting the hydrophobic character developed by the treatment.

In addition to hydroxypropylation and acetylation, esterification with octenyl succinic anhydride (OSA) demonstrates great improvements concerning the water resistance of starch-based films [67,100] and is also able to emulsify and stabilize emulsions [92]. Li et al. [101] observed that by modifying sweet potato starch with OSA, it is possible to develop edible films with less solubility and water permeability, greater elongation, and oil permeability. Taking advantage of the emulsifying power, in a more recent study, the same authors also improved the hydrophobicity of these films by incorporating oregano essential oil, transforming them into bioactive films [86,102]. Similar results were obtained by Gao et al. [103] when working with composite films of modified corn starch and soy oil.

Oxidation reactions are commonly employed for starch modification, resulting in products that find widespread use as a matrix in the formulation of food coatings due to their excellent adhesion properties and the ease with which films can be formed [75,92]. Agents such as sodium hypochlorite and hydrogen peroxide are able to increase the interaction between polymer chains, so films made from oxidized starches tend to have greater tensile strength and lower elongation [11,104]. Furthermore, the presence of carbonyl and carboxyl groups in the polymer chains limits the interaction between amylose molecules and, consequently, reduces retrogradation [105] and increases the barrier properties [106]. Biduski et al. [107] confirmed that oxidized starch triggered greater rigidity in the sorghum starch films developed in their study. In addition, Fonseca et al. [108] and Oluwasina et al. [109] also observed significant effects in reducing the solubility and water permeability of potato and cassava oxidized starch films, respectively.

The modification by acid hydrolysis involves the partial breaking of the glycosidic bonds between the amylose and amylopectin molecules, changing the structure and properties of the polymeric chain without damaging the starch granules. As a result of depolymerization, there is a reduction in the molecular weight of the polysaccharide, as well as in the swelling capacity and in the tendency to retrograde. On the other hand, water solubility, gelling power, film-forming ability, and adhesion are improved [27,92,107]. Such effects were observed by Zhang et al. [110] when studying the behavior of acid-hydrolyzed pea starch. The authors also reported an increase in the tensile strength and water vapor permeability of these films. The hydrophilic character was also enhanced in corn starch films developed by Hernández-Jaimes et al. [111].

3.2.2. Effect of Lipid and Polysaccharide Incorporation into the Film-Forming Solution

The fat’s addition aims to reduce the permeability and solubility rates of starch bioplastics. It is carried out by mixing the lipids (i.e., emulsions, essential oils, and waxes) in the film-forming solution during gelatinization or by applying lipophilic layers on or between the starch layers, in concentrations depending on the desired functionality for the film or coating. Restrepo et al. [112] incorporated essential oils of citronella and rosemary in the form of nanoemulsions in the banana starch film matrix. They observed that these lipids, in addition to reducing the solubility of the films in water, had a plasticizing effect and played a role in greater transparency and elasticity, characteristics desired by the food industry. Basiak et al. [113] developed biofilms composed of intercalated layers of wheat starch and rapeseed oil, verifying a decrease in their permeability to water vapor and O₂. It should be pointed out that the preparation of multilayer packaging is not widely used for food preservation because of the tendency of the layers to degrade over time, resulting in a heterogeneous structure with holes and fissures [52].

The incorporation of other polysaccharides has also been widely addressed for the manufacture of starch-based composites as a result of the improvements promoted in the thermo-mechanical properties of bioplastics, reducing their solubility in water and maintaining biodegradability [37].

Ali et al. [114] used cellulose and starch crystals to compose edible cornstarch films, verifying their influence on the microstructure, mechanical properties, and processing conditions of the new composites. It was observed that there were no changes in the structure and geometry of the corn starch granules. Also, the tensile strength and Young’s modulus of the films increased with the addition of both polysaccharide crystals, while the elongation at break decreased, indicating optimized films with the supplementation of reinforcing agents. Films containing cellulose crystals showed greater thermal stability, easier processing, and better mechanical properties [115]. In addition, the starch crystals showed greater protection against UV radiation, suggesting the success of their use as packaging materials for food products. Similarly, Tibolla et al. [116] achieved similar results by incorporating cellulose nano-fibers extracted from banana peel in films developed from banana starch.

Despite the advantages presented, these crystals fail in terms of gas and moisture permeability, which are relevant factors when considering food packaging. To address this limitation, various proteins, such as collagen, gelatin, corn zein, alginate, and agar, have been investigated.

Chen et al. [117] reinforced films of corn starch modified with laver, a material consisting of cellulose fibers and enriched in protein. As a result, it was found that, in addition to improving the mechanical properties of the film, when laver is added to the hot filmogenic solution and incorporated under shear forces, there is a significant reduction in water vapor permeability. Fakhouri et al. [51] developed and evaluated different edible coatings based on corn starch, gelatin, and plasticizers (glycerol or sorbitol) in grapes stored for 21 days under refrigeration. The results obtained showed that the addition of gelatin significantly increased the mechanical resistance of the coating and its permeability to water vapor, revealing less weight loss post-harvest, which favors the use of this type of coating for the preservation of fruits and vegetable quality. Pellá et al. [118] also check the effects of the incorporation of gelatin and casein in starch-based coatings used in guavas. The authors highlighted the low water vapor permeability as one of the main factors in maintaining the quality of the fruits after 9 days of storage.

3.2.3. The Reinforcement of Starch-Based Films and Coatings with Nanoparticles, Biopolymers, and Clays

The reinforcement of starch films with organic or inorganic nanoparticles, biopolymers, and clays is also an alternative to improve barrier properties. It should be pointed out that metallic compounds are generally used to minimize the spread of microbiological contaminants and, because of their low toxicity, can be added to food packaging [24,119]. Peighambardoust et al. [120] evaluated films composed of starch and silver nanoparticles (Ag), zinc oxide (ZnO), and copper oxides (CuO). It was found that the combination resulted in a synergistic effect in improving the mechanical and antimicrobial properties of the film. Similar results were found by Jayakumar et al. [121] when developing films composed of jackfruit starch and polyvinyl alcohol (PVA), incorporated with ZnO and some phytochemicals.

These composite films and some composite coatings have a bioactive character, which adds even more value to these bioplastics and their uses in the food industry, since the raw materials involved in their processing allow the food and its packaging or coating to interact in a way that prolongs shelf life and/or guarantees the microbial safety of the product [122]. The functions and technologies of active bioplastics in foodstuffs include humidity control, the elimination or absorption of gases (i.e., O₂ and carbon dioxide—CO₂), and the application of antimicrobial and antioxidant agents [123].

Nieto-Suaza et al. [124] developed a bioactive film composed of banana starch, aloe vera gel, and curcumin, a highly hydrophobic substance that leads to reduced permeability to water vapor, increased tensile strength, and reduced elongation at break. Similarly, Iamareerat et al. [125] obtained an antimicrobial film for meat products by combining cassava starch, cinnamon essential oils, and clay particles (sodium bentonite). Also, Kang et al. [65] made an antimicrobial film from the incorporation of clove essential oil into Job’s tear (Coix lachryma-jobi L.) starch, and Piñeros-Hernandez et al. [126] achieved the same characteristics by mixing cassava starch and rosemary extracts.

To conclude, it is evident that the functionalization of starch-based bioplastics presents significant challenges. Additionally, the chemical modification processes involved in functionalization can raise concerns regarding environmental impact and biodegradability, potentially undermining the eco-friendly nature of these materials. Addressing these challenges requires careful consideration of the entire life cycle of these materials, from production and functionalization to disposal and end-of-life management. It is important to acknowledge that, like traditional petroleum-based plastics, some bio-based plastics also lack recyclability. Consequently, there is a growing sentiment advocating for the selective use of bioplastics tailored to specific needs. Nonetheless, it is imperative to balance these environmental drawbacks of bioplastics with the detrimental effects of conventional plastics.

4. Application of Starch-Based Bioplastics in Food Preservation

Films and coatings cast in a laboratory environment have specific properties that may vary when these bioplastics are applied to wrap or cover food products. According to Thakur et al. [49], in a commercial approach, starch-based films and coatings stand out because of their good mechanical, optical, and efficient CO₂ and O₂ barrier properties, but the effects of these materials in food preservation must be evaluated from case to case. Several studies report positive effects on the shelf-life extension of fruits, vegetables, cheese, meat, and fish products when starch-based films and coatings are applied. The pros observed recently are presented in the next sections.

4.1. Fruits and Vegetables

Considering fresh fruits and vegetables, starch-based films and coatings are applied to improve the retention of color, flavors, acids, and sugar compounds, guaranteeing the maintenance of quality during shipping, storage, and commercialization [51].

Table 3. Starch-based films and coatings applied to fresh fruits and vegetables.

Food Product	Polymers	Main Additives	Packaging Material	Main Results	Reference
Bananas	- Rice starch (3%, w/w) - ι-carrageenan (1.5%, w/w)	- Sucrose ester fatty acids (2%, w/w) - Glycerol (1%, w/w)	Edible coating	Delayed ethylene biosynthesis and chlorophyll degradation; reduced respiration rate and weight loss; retention of fruit firmness for the first 6 days. The shelf life was extended for 12 days.	[127]
Bananas	- Cassava starch (30%, w/v)	- Clove essential oil (0.8%, w/v)	Active coating (antifungal properties)	Reduced mass loss, soluble solids content, and titratable acidity in all varieties studied.	[128]
Strawberries	- Corn starch (7%, w/w) - Chitosan (2.5%, w/w)	- Glycerin (0.5%, w/w) - Cinnamaldehyde (VC)	Active film (antibacterial properties)	Reduced soluble solids content, titratable acidity, and weight loss rate. The shelf life was ex-tended for 11 days.	[129]
Red Crimson grapes	- Corn starch (NR) - Gelatin (NR)	- Sorbitol (NR)	Edible coating	Reduced weight loss and improved appearance after 21 days of storage under refrigerated conditions.	[51]
Fresh-cut apples	- Rice starch (15%, w/v) - Fish protein (85%, w/v)	- Pink pepper phenolic extract (6%, w/v) - Glycerol (25%, w/w)	Active coating (antioxidant properties)	Reduced enzymatic browning for 12 days of storage.	[130]
Cherry tomatoes	- Corn starch (0.465%, w/w)	- Aloe vera gel (0.465%, w/w) - Glycerol (0.07%, w/w)	Active coating (antifungal properties)	Reduced fungal incidence and weight loss after 14 days of storage.	[131]
Guavas	- Cassava starch (2%, w/v) - Chitosan (2%, w/v)	- Lippia graciliis essential oil (VC) - Glycerol (VC)	Active coating (antibacterial properties)	Delayed ripening process; reduced browning and titratable acidity; inhibition of bacteria growth and color development after 10 days of storage at room temperature.	[132]

NR = Not reported.

summarizes the main achievements of recent studies performed in this area. Some authors did not provide information about the concentration of the polymers and additives used.

Considering that, Thakur et al. [127] spread rice starch-ι-carrageenan edible coatings blended with sucrose fatty acid esters over the surface of whole and unpeeled bananas. It was observed that the coating was able to control the O₂ transmission rates, the ethylene production during ripening, and the weight loss of the fruits. Moreover, an improvement in firmness and a slower emergence of browning and spotting in banana peel were seen, prolonging the post-harvest fruits’ shelf life by 12 days. Similarly, Sousa et al. [128] evaluated the quality of different banana varieties coated with a film made with cassava starch and clove essential oil during 8 days of storage. The composite starch-based film provided a reduction in mass loss, total soluble solids, and total titratable acidity in all samples studied, contributing to a delayed senescence process.

The incorporation of bioactive compounds has led to the development of more effective starch-based films and coatings. Adding antioxidants, anti-inflammatory, and antimicrobial agents to the filmogenic matrix may alter the properties of films and coatings, reducing the need for preservatives and enhancing the quality of food products. Wang et al. [129] stated that films made with corn starch, chitosan, and cinnamaldehyde were able to keep the fresh effect on strawberries, slowing down the physiological changes, maintaining the nutritional value, and extending the shelf life of these fruits for 11 days.

An improvement in appearance and reduced weight loss were also pointed out by Fakhouri et al. [51] for Red Crimson grapes coated with a corn starch and gelatin mixture after 21 days of storage under refrigerated conditions.

Romani et al. [130] tested composite films made with rice starch, fish protein, and pink pepper phenolic extract on fresh-cut apples. It was observed that the antioxidant compounds inhibited the activity of peroxidase, preventing the enzymatic browning of apple slices for 12 days of storage.

Ortega-Toro et al. [131] developed coatings for cherry tomatoes using corn starch and aloe vera gel. Alongside a massive retardation in fruits’ weight loss after 14 days of storage, the results showed the antifungal capacity of aloe vera gel, which can be a natural, non-toxic alternative to synthetic fungicides in the preservation of fruits and vegetables. Similarly, Aquino et al. [132] applied coatings made with cassava starch, chitosan, and Lippia gracilis Schauer essential oil to guavas. The shelf-life study indicated an inhibition of bacteria growth during storage at room temperature for 10 days, no significant differences in total soluble solids content, a lower titratable acidity, and a delay in fruit color changes with ripening.

4.2. Dairy Products

Starch-based films and coatings with antimicrobial and antioxidant agents have also been used in dairy product preservation and packaging. Mei et al. [133] coated Mongolian cheese with a chestnut starch-chitosan-perilla oil solution and observed its effects on the product after 30 days of storage. The coating’s efficiency was proven as the samples analyzed had lower moisture transfer rates and lower relative weight loss, as well as a delay in the growth of bacteria and fungi. Similarly, Yang et al. [134] observed the antimicrobial and antioxidant effects of a film composed of foxtail millet starch and clove leaf oil on Queso Blanco cheese’s quality. It was noted that there was a decrease in the population of Listeria monocytogenes after 24 days of storage and a significant reduction in lipid oxidation, expressed by a drop in the concentration of thiobarbituric acid-reactive substances. Also, Ollé Resa et al. [135] evaluated the effectiveness of composite films made with tapioca starch, natamycin, and nisin to maintain the microbiological stability of Port Salut cheese under refrigeration. The authors concluded that the film inhibited the growth of yeasts and molds and also controlled the growth of psychrotrophic bacteria originally present in the product.

To prevent lipid oxidation, Perazzo et al. [136] applied cassava starch films incorporated with green tea and palm oil extracts as the primary packaging for butter. The results showed oxidative protection with a decrease in the peroxide index of the samples after 45 days of storage; however, it is recommended to incorporate the antioxidant additives in low concentrations.

4.3. Fish and Meat Products

Preservation of meat, fish, and derived products must be achieved by controlling their exposure to O₂ and CO₂ and, consequently, reducing some deterioration phenomena such as microbial proliferation and lipid and protein oxidation, which lead to quality decay in terms of flavor, color, texture, and nutritive value [137]. Alongside the gas barrier provided by starch-based films and coatings themselves, a higher level of protection against degradation can be achieved with the incorporation of natural antimicrobials and antioxidants in the filmogenic solution. The main positive effects of fish and meat product preservation can be observed in

Table 4. Starch-based films and coatings applied to fish and meat products.

Food Product	Polymers	Main Additives	Packaging Material	Main Results	Reference
Rainbow trout fillets	- Quinoa starch (4%, w/v)	- Sage oil (2%, w/w) - Lemon oil (2%, w/w) - Glycerol (2%, w/w)	Active film (antimicrobial and antioxidant properties)	Reduced microbial load and lipid oxidation after 15 days of storage.	[138]
Beef	- Potato starch (0.025%, w/v)	- Green tea extract (5%, w/w) - Butylated hydroxytoluene (5%, w/w) - Glycerol (0.006%, w/v)	Active film (antioxidant properties)	Decreased metmyoglobin formation and lipid oxidation.	[139]
Pork meatballs	- Cassava starch (5%, w/v)	- Glycerol (2%, w/w) - Cinnamon essential oil (2.5%, w/w) - Sodium bentonite nanoclay (0.75%, w/w)	Active film (antimicrobial properties)	Inhibition of microbial growth until 96 h of storage below FDA limits.	[125]
Raw beef fillets	- Corn starch (6%, w/v)	- Glycerol (50%, w/v) - Cooking gum (2%, w/v) - Cinnamon essential oil (3%, w/v) - Clove essential oil (3%, w/v)	Active film (antimicrobial and antioxidant properties)	Reduced microbial load; improved meat color stability after 15 days of refrigerated storage.	[140]
Fresh Frankfurt sausage	- Tumeric starch (35%, w/w) - Gelatin (50%, w/w)	- Glycerol (15%, w/w)	Active film (antimicrobial properties)	Maintenance of physicochemical attributes (pH, texture profile, moisture, and color); reduced microbial growth during a 30-day storage period at 5 °C and 10 °C.	[141]
Shrimp	- Sweet potato starch (50%, w/v)	- Glycerol (2%, w/w) - Thyme essential oil (VC)	Active coating (antimicrobial and antioxidant properties)	Reduced microbial growth, melanosis, oxidation, and loss of firmness of shrimp samples during 8 days of storage at 4 °C.	[142]

. Some authors did not provide information about the concentration of the polymers and additives used.

Alak et al. [138] evaluated the microbiological and chemical effects of films made from quinoa starch and sage or lemon essential oils in the preservation of rainbow trout fillets. After 15 days of storage under refrigerated conditions, the authors observed that the single use of quinoa starch films was effective in decreasing the microbial load, although composite films containing sage essential oil promoted a stronger barrier against all bacterial species analyzed. In addition, the films made with lemon essential oil were the most effective in preventing lipid oxidation.

Similarly, Nisa et al. [139] reported an improvement in the oxidative stability of fresh beef wrapped with potato starch films incorporated with butylated hydroxytoluene and green tea extract. In the same way, Iamareerat et al. [125] used composite films made with cassava starch, cinnamon essential oil, and sodium bentonite nanoclay in pork meatball conservation. It was pointed out that the new packaging material significantly inhibited microbial growth until 96 h below the FDA limits for foods. Similar results were observed by Radha Krishnan et al. [140] for beef fillets coated with an emulsion of cassava starch and clove and cinnamon essential oils and Tosati et al. [141] when using a coating blend of turmeric starch and gelatin for sausages.

As noted, starch-based biodegradable films are pivotal in food preservation, acting as protective barriers against moisture and oxygen to mitigate oxidation and microbial spoilage. Additionally, these films incorporate antimicrobial agents to disrupt microorganism growth and function as antioxidants to prevent lipid oxidation, maintaining food quality and freshness while ensuring safety through their antibacterial properties [143].

Furthermore, advancements in bioactive and intelligent starch-based films offer enhanced preservation capabilities, with bioactive films reducing microbial reproduction and intelligent films monitoring food freshness. Incorporating plant extracts, essential oils, and nanoparticles further improves film properties, with potential for applications like pH-responsive warning signals in fish products [144].

Understanding these mechanisms facilitates the development of tailored starch-based biodegradable films optimized for various food packaging applications, promoting effectiveness and sustainability. Future research should explore additional biologically active starch-based films to expand their utility in food preservation.

5. Conclusions

The widespread use of synthetic materials is resulting in serious ecological problems because of their non-biodegradability. Among the effects observed, it is highlighted the pollution of the aquatic environment and the accumulation of microparticles in marine animals, which can, in the long term, compromise human health as a result of their toxicity. For the packaging industry, a strategic solution focuses on the development of sustainable new products that can challenge the traditional polymeric matrixes found on the market.

In the context of food packaging and preservation, starch has captured the interest of the scientific community. However, only a limited number of studies address the optimization of starch extraction processes to ensure desired molecular properties and improved extraction yields. Furthermore, the majority of studies have focused on starch matrices derived from cereals, tubers, and fruits commonly used as dietary staples. Future research endeavors should prioritize exploring unconventional sources, including residues and by-products from agricultural processes.

It is common to add glycerol and sorbitol as plasticizers in the starch-based filmogenic solution to improve films’ flexibility, but there are few records about the addition of natural extracts for this purpose, so it may be investigated in future work. Moreover, the starch source may have a minority of constituents that can improve the hydrophobicity of the starch-based bioplastics. Priority should be given to the extraction and incorporation of these compounds in the film-forming solution for extensive use of the matrix.

Most studies have been observed to concentrate on the preservation of fresh fruits and vegetables. This emphasis arises from the fact that these foods generally require less extensive protection against water vapor and other gases. However, the barrier properties of the bioplastics developed recently are continually improving to meet the needs of different markets, and although the vast majority have not yet been tested on food, the results obtained in laboratory tests suggest their potential use as a substitute. traditional plastic packaging.

The versatility of starch, derived from agricultural sources, has positioned it as a frontrunner in the quest for sustainable materials. Its low cost, wide availability, high extraction yield, edibility, nutritional value, biodegradability, and biocompatibility make it a particularly attractive candidate for eco-conscious initiatives. This exploration into starch-based biodegradable plastics not only addresses the urgent need for environmentally friendly alternatives but also aligns with the broader global commitment to fostering a more sustainable and circular economy.

This paper addresses some of the major challenges raised by the vast subjects proposed. However, there are additional areas that warrant discussion. For instance, exploring the utilization of by-products generated during starch extraction and processing, such as starch slurry waste or agricultural residues, to develop value-added products for sustainable food packaging presents a significant opportunity. Furthermore, incorporating nanomaterials like nanocellulose, nanoclays, or nanofibers into starch-based biopolymers could enhance their mechanical strength, barrier properties, and antimicrobial activity, thereby improving performance while reducing material usage and environmental impact. Additionally, promoting consumer awareness and acceptance of starch-based biopolymers as sustainable alternatives to conventional plastics for food packaging is crucial. Educating consumers about the environmental benefits, recyclability, and biodegradability of these materials can encourage widespread adoption and stimulate market demand.