3.1 Scanning electron microscopy and particle size
The morphology of starch granules, including their shape and size, is a fundamental aspect that determines various properties and industrial applications. The configuration of the granules significantly influences aspects such as gelatinization, water absorption capacity, swelling, solubility, and film formation [13]. Figures 2 and 3 present the SEM results and particle size analysis of starches from unconventional sources.
The starch granules of Talisia floresii Standl predominantly exhibit a spherical and uniform shape with an average diameter of 18.7 µm. The uniformity in the shape and size of these starch granules favors the formation of homogeneous films, which translates into excellent mechanical properties and biodegradability, making them ideal for biodegradable packaging. Additionally, the small and spherical granules of this starch gelatinize at lower temperatures due to a greater surface area relative to volume, facilitating water absorption and the dissociation of crystalline structures. This gelatinization behavior is advantageous for industrial applications requiring high processing temperatures.
Furthermore, the small granule size offers a high-water absorption capacity and gel formation, making it ideal as a gelling and thickening agent in food products such as soups, sauces, desserts, and dairy products. These products require stability and consistency, characteristics that can be provided by this type of starch. The granule size of Talisia floresii Standl starch is similar to that reported for other starch sources [14]. These results are comparable to those found in quinoa starch, which has an average particle size of 10.55 µm and polyhedral-shaped granules [15]. The similarity in the shape and size of the granules suggests that both starches could have similar functional properties, such as the ability to form stable gels and high water absorption capacity.
The SEM provides detailed insights into the morphology of Melicoccus bijugatus starch granules. The granules predominantly exhibit oval shapes, with smooth and uniform surfaces, averaging a diameter of 11.8 µm, with no evidence of fissures or fractures. This size offers several advantages, including a greater water absorption capacity due to its high specific surface area compared to larger granules. A higher specific surface area increases the contact area with water, allowing for more efficient interaction between water molecules and the granule surface, facilitating absorption. It has been reported [16] that starches with this granule size typically exhibit an internal structure with pores and channels, enhancing their water retention capacity. This porosity allows uniform water entry into the granule, increasing its absorption capacity. The hydration of amylose and amylopectin chains causes the granules to swell, resulting in volume increase, which is crucial for applications requiring gel formation or solution thickening.
The high specific surface area of Huaya starch allows significant water absorption due to its porous structure and swelling capacity, making it beneficial for various industrial applications. These properties enhance the texture of food products, facilitate controlled drug release, and contribute to bioplastic formation. Additionally, the oval and uniform shape of the granules promotes the formation of films with good mechanical properties and biodegradability, useful in the packaging industry. This morphology is similar to achira starch (Canna edulis), which exhibits an average particle size of 20.12 µm and elongated, smooth granules [17]. Both starches could be suitable for applications requiring a smooth texture and easy dispersion in water, such as in food and pharmaceutical products.
Ramón starch granules display an oval to spherical shape with an average diameter of 14.2 µm. The granules show a smooth and uniform surface, with no evidence of porosity or fissures. Reports in the literature consistently show the morphology of Brosimum alicastrum Swarts starch granules to be oval and spherical, with granule sizes ranging from 5 to 20 µm [12]. The smooth surface of the granules is also a common finding, suggesting a uniform structure that can positively influence the functional properties of the starch, such as swelling capacity and solubility. This size and morphology are similar to mung bean starch (Vigna radiata), which has an average particle size of 17.22 µm and spherical granules [18]. The similarity in structure suggests that Ramón starch could share functional properties with mung bean starch, such as good gel formation capacity and thermal stability.
The similarities in morphology reported by different authors indicate that environmental conditions and extraction methods have minimal impact on the morphological characteristics of Ramón starch granules. This highlights the stability of these characteristics, which is beneficial for industrial applications, as it allows for more precise prediction of starch behavior in various applications.
Starch granules from Enterolobium cyclocarpum predominantly exhibit round to oval shapes with an average diameter of 30 µm. Additionally, a smooth surface without significant fractures is observed, indicating high structural integrity. These results contrast with sago starch, which has an average particle size of 28.89 µm and rounded, smooth granules [19]. The difference in granule surface suggests that Parota starch might have a higher water absorption capacity and a different gelatinization rate, which could be useful in applications requiring rapid hydration and paste formation. Furthermore, Mieles-Gómez et al. [20] reported a particle size for mango starch (Mangifera indica) with an average particle size of 25.43 µm and irregularly shaped, rough-surfaced granules. Both Parota and Mango starches could have similar applications in the food and cosmetic industries, where high water absorption capacity and specific textures are required. In the pharmaceutical industry, it is used in tablets and capsules due to its high-water absorption and swelling capacity, which facilitates compaction in tablet manufacturing. The oval shape and smooth surface facilitate greater water absorption and uniform swelling, aiding in the formation of films with good mechanical properties and biodegradability, thus improving product texture. In the packaging industry, it can be used in biodegradable packaging, disposable utensils, and agricultural films.
The analysis of granule size from four unconventional starch sources Talisia floresii Standl, Melicoccus bijugatus Jacq, Brosimum alicastrum Swarts, and Enterolobium cyclocarpum reveals significant differences affecting their potential industrial applications. The obtained sizes indicate that each type of starch can influence its physicochemical properties and, consequently, its potential uses in various industries.
Colok starch is particularly suitable for applications requiring high water absorption capacity and stable gel formation. These characteristics make it ideal as a thickening and gelling agent in the food industry, as well as in the manufacture of bioplastics and biodegradable materials.
Huaya starch may exhibit high water absorption capacity and stability in gel formation. These properties are advantageous for the pharmaceutical industry, where it can be used as an excipient in tablet formulation and as a disintegrant, facilitating controlled drug release. Additionally, it is useful in the food industry to improve the texture of products such as soups, sauces, and desserts.
Ramón starch shows high water absorption and gel formation capabilities, similar to Colok and Huaya starches, making it suitable for applications that require different textures and consistencies. It is also appropriate for use in the food and pharmaceutical industries, as well as in the production of bioplastics and textile materials.
Parota starch stands out for its granule size, which may enable it to absorb large amounts of water and form very stable gels. These properties make it especially useful in the paper industry as a sizing agent and in the textile industry for finishing and sizing. Furthermore, its large granule size is beneficial for manufacturing bioplastics and biodegradable materials, providing greater strength and flexibility.
These unconventional starch sources exhibit specific granule sizes and physicochemical properties that make them suitable for various industrial applications. The starches from Colok, Huaya, Ramón, and Parota offer valuable and sustainable alternatives in the food, pharmaceutical, bioplastic, textile, and paper industries, allowing for the optimization of products and processes through their unique water absorption, gel formation, and mechanical properties.
3.2 Fourier transform infrared spectroscopy (FTIR) analysis
FTIR analysis was employed to investigate the functional group arrangements and interactions within the unconventional starch molecules structure. Figure 4 illustrates the FTIR spectra for starches derived from Colok, Huaya, Ramon, and Parota. A broad absorption band at 3332 cm− 1 corresponds to the vibrations of free hydroxyl groups, indicating minimal inter- and intramolecular interactions among these groups due to the molecular weight of OH–. The band at 2927 cm− 1 is attributed to CH stretching linked to the methylene hydrogen atoms in the ring structure. The presence of absorbed water in the starch is indicated by a band at 1637 cm− 1 [21]. In the fingerprint region characteristic of starch, major peaks appear at 1144, 1075, and 1009 cm− 1, corresponding to the C–O–C bonds in glucose, and at 851 cm− 1, associated with pyranose [22]. Additionally, the absorbance band at 1047 cm− 1 is indicative of the crystalline structure of the starch, while the band at 1022 cm− 1 pertains to the amorphous regions [23]. Starches comprise both amorphous and crystalline regions, and the proportion of each is crucial for predicting the polysaccharide's behavior during processing and storage. Some researchers have highlighted the significance of the FTIR bands around 1047 cm− 1, associated with the crystalline regions, and 1022 cm− 1, associated with the amorphous regions [24]. The ratio of these bands is indicative of the degree of order within the starch structure. The calculated values for the starches isolated from various sources were as follows: Colok starch had a value of 1.7, Huaya starch measured at 0.9, Ramon starch was determined to be 1.6, and Parota starch had a value of 0.6. The FTIR collected data indicates that the starch isolation method was executed effectively.
3.3 Differential scanning calorimetry
The gelatinization temperature is a critical parameter that indicates the temperature at which starch begins to absorb water and swell, forming a viscous paste. Figure 5 presents the DSC results conducted on the starches. The results specify that the gelatinization temperature of Colok starch begins around 61°C and reaches its peak heat flow at 105°C, with a value of 4.3 W/g. This broad range of transition temperatures reflects a complex and highly ordered crystalline structure, a characteristic that may be associated with a high amylose content and the presence of different levels of crystallinity within the granules [25]. The high gelatinization enthalpy, calculated at approximately 106.4 J/g, suggests that Colok starch possesses a highly organized and amylose-rich structure. Amylose, known for forming linear strands that group into crystalline regions, increases the enthalpy required for the phase transition during gelatinization [10]. This behavior significantly differs from other common starches such as corn, which generally exhibits gelatinization temperatures of 70–80°C and enthalpies of 14–15 J/g, indicating lower thermal stability and a less ordered structure [26]. The analysis of the peaks in the DSC curve reveals a series of thermal transitions, with a maximum peak at 105°C and subsequent fluctuations in heat flow up to 149.03°C. These transitions suggest the presence of multiple types of crystallinity and variations in the thermal stability of Colok starch structures, possibly due to the coexistence of crystalline and amorphous domains [27].
Colok starch exhibits a higher gelatinization temperature and greater gelatinization enthalpy, highlighting its thermal stability and complex crystalline structure. These characteristics make it particularly suitable for applications in the food industry, where high thermal stability and resistance to retrogradation are required for products that must maintain their texture and consistency during thermal processing and prolonged storage [11]. Additionally, in the pharmaceutical industry, the thermal stability of Colok starch is advantageous for use as an excipient in the formulation of tablets and capsules, ensuring that active ingredients are released in a controlled manner and maintain their structural integrity during storage [28].
The DSC analysis results indicate that the gelatinization temperature of Huaya starch begins around 50°C and reaches its peak at 82°C with a heat flow of 0.16726 W/g. This range of transition temperatures suggests that Huaya starch possesses a relatively ordered crystalline structure, though less complex compared to other conventional starches like Colok, which showed higher transition temperatures and greater gelatinization enthalpy. The lower gelatinization enthalpy of Huaya starch stipulates that less energy is required to disrupt its crystalline structures, which could be related to a lower amylose content or a less densely packed molecular arrangement. This characteristic is advantageous for applications requiring gelatinization at lower temperatures, such as certain food and pharmaceutical products. By comparison, corn starch, with a gelatinization temperature between 70–80°C and an enthalpy of approximately 14–15 J/g, requires more energy for complete gelatinization [28]. This contrast highlights the thermal efficiency of Huaya starch, making it suitable for industrial processes needing milder operating conditions.
The industrial applications of Huaya starch are varied due to its unique thermal properties. In the food industry, the low gelatinization temperature and enthalpy make this starch ideal for products requiring rapid gelatinization at lower temperatures, such as sauces and desserts that need a smooth and consistent texture [29]. In the pharmaceutical industry, Huaya starch can be used as an excipient in the manufacturing of tablets and capsules, ensuring controlled release of active ingredients at lower body temperatures, thus enhancing medication efficiency [28].
The DSC analysis of Huaya starch reveals thermal properties indicating a less complex crystalline structure and lower thermal stability compared to other starches. These characteristics make Huaya starch suitable for industrial applications requiring rapid and lower-temperature gelatinization processes.
DSC analysis of Ramón starch reveals thermal and structural properties that make it particularly suitable for various industrial applications. The results show that the gelatinization temperature of Ramón starch begins around 60°C and extends to approximately 100°C, reaching a peak heat flow at 83°C with a value of 15.7 W/g. This wide range of transition temperatures suggests a complex and highly ordered crystalline structure that requires a considerable amount of energy to break down. This high gelatinization enthalpy denotes a highly organized internal structure, possibly with a significant amylose content, which is consistent with the thermal stability observed in similar starches [30]. The thermal behavior of Ramón starch contrasts with that of conventional starches such as corn starch, which shows lower gelatinization temperatures and lower gelatinization enthalpy. This higher energy requirement for the phase transition of Ramón starch can be attributed to its more rigid and crystalline structure, which includes a combination of amorphous and crystalline domains that disorganize at different temperatures [31]. This behavior makes Ramón starch particularly suitable for applications demanding high thermal resistance and low retrogradation, which is crucial for the stability and texture of processed food products such as soups, sauces, and frozen items [32]. Additionally, the high thermal stability and ordered structure of Ramón starch make it an ideal candidate for use in the pharmaceutical industry. It can be used as an excipient in the formulation of tablets and capsules, ensuring controlled release of active ingredients and maintaining structural integrity during storage. These properties are essential to ensure the efficacy and safety of medications [33].
In the bioplastics industry, Ramón starch offers significant advantages due to its ability to form stable gelled structures. This ability translates into improved mechanical properties, making Ramón starch suitable for producing biodegradable packaging and other sustainable materials. The durability and strength derived from its high gelatinization enthalpy can provide a viable and eco-friendly alternative to conventional plastics, contributing to the reduction of plastic pollution [34].
Parota starch exhibits thermal characteristics that position it as a promising material for various industrial applications. The data obtained reveal that the gelatinization temperature of Parota starch starts around 56°C and extends up to approximately 109°C, with a peak heat flow at 77°C and a value of 0.006 W/g. This wide range of transition temperatures suggests a complex and well-organized crystalline structure that requires a considerable amount of energy to disorganize and gelatinize. The high gelatinization temperature indicates significant thermal stability, suggesting that Pich starch may contain high levels of amylose, which contributes to structural rigidity and thermal resistance [35].
Du et al. al [36] reported gelatinization at lower temperatures with lower enthalpy for corn starch similar to Parota starch that shows higher thermal stability and a more robust crystalline structure. This characteristic is advantageous for applications requiring materials with high thermal resistance and low retrogradation, such as food products that need to maintain their texture and consistency during thermal processing and prolonged storage [32]. The ability of Parota starch to maintain its structure at elevated temperatures makes it ideal for these industrial uses. In the pharmaceutical industry, the high thermal stability and ordered structure of Parota starch make it an ideal candidate for use as an excipient in tablet and capsule formulation. Thermal stability ensures that active ingredients are released in a controlled manner and maintain their structural integrity during storage, which is essential for the efficacy and safety of medications [1]. The high gelatinization enthalpy and thermal behavior of Parota starch position it as a valuable excipient for advanced pharmaceutical applications.
The DSC analysis of Colok, Huaya, Ramón, and Parota reveals distinctive thermal characteristics that highlight their potential for various industrial applications. Colok starch showed a high gelatinization temperature and significant enthalpy, indicating a complex crystalline structure and high thermal stability, making it ideal for food products requiring retrogradation resistance and stability during thermal processing [15, 6]. On the other hand, Huaya starch, with its lower gelatinization temperature, suggests suitability for applications requiring gelatinization processes at lower temperatures, beneficial for the food and pharmaceutical industries where energy efficiency and texture control are sought [1]. Ramón starch stood out for its thermal stability and high gelatinization enthalpy, similar to Colok starch, making it suitable for products demanding high thermal resistance and low retrogradation, also promising for bioplastics applications due to its mechanical properties [7]. Finally, Parota starch presented a wide range of gelatinization temperatures and high enthalpy, implying a robust crystalline structure and high thermal stability, making it ideal for industrial applications requiring high durability and resistance, such as biodegradable packaging and pharmaceutical excipients [30].
3.4 Thermogravimetry Analysis
The TGA analysis of the starches from unconventional sources provides essential information about their thermal properties and stability. The results show significant differences in the thermal behavior of each starch, suggesting structural diversity that can influence their industrial applications. Colok starch exhibits notable thermal stability with a maximum mass loss temperature around 300°C. This behavior suggests a highly ordered crystalline structure and greater resistance to thermal decomposition, consistent with its high gelatinization enthalpy observed in previous analyses [35]. The ability of Colok starch to maintain its structure at high temperatures makes it particularly suitable for applications in the food and bioplastics industries, where high thermal stability and resistance to retrogradation are required. In contrast, Huaya starch shows significant mass loss at lower temperatures, around 250°C. This indicates lower thermal stability compared to Colok starch, which can be attributed to lower crystallinity and possibly a higher content of amorphous components [36]. This characteristic suggests that Huaya starch may be more suitable for applications that do not require high processing temperatures, such as certain food and pharmaceutical products, where energy efficiency and texture control are crucial.
Parota starch exhibits thermal stability comparable to that of Colok starch, with a maximum mass loss temperature also around 300°C. Its high thermal resistance and ability to form stable gel structures make Pich starch an ideal candidate for the production of bioplastics and sustainable materials. The durability and resilience derived from its thermal behavior highlight its potential to replace conventional plastics in applications requiring biodegradable and eco-friendly materials [28].
Ramón starch presents intermediate thermal stability, with a maximum mass loss temperature around 280°C. This characteristic denote a moderately crystalline structure that provides good thermal resistance but with less structural complexity compared to Colok and Parota. This thermal stability makes Ramón starch suitable for both food and pharmaceutical applications, where a balance between thermal stability and ease of processing is required [1].
The TGA analysis reveals that unconventional starches exhibit distinct thermal behaviors, reflecting their unique structures and compositions. Colok and Parota starches stand out for their high thermal stability, making them ideal for applications in bioplastics and materials resistant to high temperatures. Huaya starch, with its lower thermal stability, is more suitable for moderate temperature applications, while Ramón starch offers a balance that makes it versatile for various industrial applications.
The TGA analysis of Colok, Huaya, Parota, and Ramón starches has revealed significant differences in their thermal behavior, highlighting the structural diversity and potential industrial applications of these unconventional materials (Fig. 6). Colok and Parota starches demonstrated notable thermal stability, with maximum mass loss temperatures around 300°C, indicating a highly ordered crystalline structure resistant to thermal decomposition. These properties make them especially suitable for applications in the bioplastics and biodegradable materials industries, where durability and high-temperature resistance are required [28]. On the other hand, Huaya starch showed significant mass loss at lower temperatures, approximately 250°C, suggesting lower thermal stability and a less crystalline structure, making it more suitable for applications that do not involve intensive thermal processing, such as certain food and pharmaceutical products [1]. Ramón starch, with intermediate thermal stability and a maximum mass loss temperature of around 280°C, offers a balance that makes it versatile for both food and pharmaceutical applications, providing an adequate balance between thermal stability and ease of processing [36]. These findings underscore the importance of continuing to explore unconventional starch sources in the Yucatán Peninsula, highlighting their potential to meet the growing demands of various industries through the development of innovative and sustainable materials.
The activation energy provides insight into the amount of energy required to initiate the thermal decomposition of a material, allowing for the assessment of its resistance to thermal degradation and its suitability for various applications. In this study, the activation energies of the starches from Colok, Huaya, Ramón, and Parota were calculated using the Coats-Redfern method [37], yielding values of 142.35 kJ/mol, 104.47 kJ/mol, 111.38 kJ/mol, and 103.46 kJ/mol, respectively. These values indicate significant differences in the thermal stability of the analyzed starches, which can be attributed to their unique structures and compositions.
Colok starch showed the highest activation energy, suggesting high resistance to thermal decomposition. This behavior may be related to higher crystallinity and a more ordered structure, making it difficult to break molecular bonds during heating. The high thermal stability of Colok starch makes it suitable for applications requiring high heat resistance, such as in the bioplastics and biodegradable packaging industries [7]. On the other hand, Huaya starch presented the lowest activation energy, indicating greater susceptibility to thermal decomposition. This result suggests that Huaya starch possesses less crystalline structure and possibly a higher content of amorphous components, which facilitate the breaking of molecular bonds at lower temperatures. The lower thermal stability of Huaya starch might limit its use in high-temperature applications, but it could be advantageous in processes requiring rapid thermal decomposition, such as in food and pharmaceutical applications [1]. Ramón starch showed intermediate activation energy, indicating moderate thermal stability. This behavior suggests that Ramón starch exhibits less ordered crystalline structure compared to Colok starch, but more ordered than that of Huaya starch. The moderate thermal stability of Ramón starch makes it versatile for various applications, including food, pharmaceutical products, and biodegradable materials [36].
Parota starch also unveiled intermediate activation energy, similar to Ramón starch. This result indicates that Parota starch presents comparable thermal stability, making it suitable for industrial applications requiring moderate thermal resistance. The versatility of Parota starch, along with its thermal stability, suggests its potential for use in a wide range of products, from bioplastics to pharmaceutical excipients [38].
3.5 X-ray diffraction (XRD)
In Fig. 7, the results of the X-ray diffraction (XRD) study for the starches are presented. The XRD analysis of Colok starch provides a detailed view of its crystalline structure. The data obtained show well-defined diffraction peaks at specific 2θ positions, indicating the presence of crystalline regions within the starch matrix. The calculated crystallinity index for this starch is 33%, suggesting a mixture of crystalline and amorphous regions. The peaks identified in the X-ray diffraction pattern are characteristic of an A-type crystalline structure, common in plant-based starches. This structure is characterized by the formation of double helices of amylose, which pack in an orderly arrangement. The main diffraction peaks observed are at 2θ angles of approximately 15°, 17°, 18°, and 23°, indicative of the presence of these double helices and their organization into a crystalline lattice. The 33% crystallinity index indicates that while there is a significant portion of the starch structure that is crystalline, there is also a considerable amount of amorphous material. This combination of crystalline and amorphous regions can influence the physical and functional properties of Colok starch. The crystalline regions contribute to the thermal and mechanical stability of the starch, while the amorphous regions can affect its water absorption and gelatinization capacity. The thermal behavior of Colok starch, influenced by its crystalline structure, is relevant for various industrial applications. In the food industry, a starch with moderate crystallinity like Colok's can provide a desirable texture in products such as sauces and puddings, where stable gel formation is required. Additionally, the presence of crystalline regions can improve retrogradation resistance, which is beneficial for the preservation and stability of food products. In non-food applications, such as bioplastic manufacturing, the crystalline structure of Colok starch can influence the mechanical and barrier properties of the final material. A higher crystalline content is generally associated with greater rigidity and lower permeability to water and gases, which is desirable in biodegradable packaging. Furthermore, crystallinity can affect the biodegradability of the material, with crystalline regions decomposing more slowly than amorphous ones. The XRD analysis of Colok starch reveals an A-type crystalline structure with a crystallinity index of 33%. This structure significantly influences its thermal, mechanical, and water absorption properties, making Colok starch a potentially valuable source for applications in both the food industry and the production of bioplastics and other biodegradable materials. These results are similar to those reported by other authors for other unconventional starches. Yang et al. [39] reported that banana starch exhibits an A-type crystalline structure, with peaks at positions similar to those of Colok starch. This similarity in crystalline structure suggests that the functional properties of both starches could be comparable, especially in terms of thermal stability and gel-forming capacity. Additionally, No, Shin [40] studied starches from different sources and found that rice and corn starches also exhibit an A-type crystalline structure. The reported crystallinity index for these starches ranges between 30% and 40%, which is in line with the crystallinity index of Colok starch. This consistency in crystallinity values indicates that Colok starch could have similar applications in the food industry and bioplastic production, where a combination of thermal stability and adequate mechanical properties is required. On the other hand, Wu et al. [41] studied the modification of starches using physical techniques and observed that the crystallinity of starches significantly influences their final properties. Starches with higher crystallinity tend to show greater retrogradation resistance and better film formation, which is crucial for applications in food packaging and the manufacture of biodegradable materials. Colok starch, with its 33% crystallinity index, could benefit from these properties, making it a viable candidate for these applications.
The XRD analysis of Huaya starch reveals a diffraction pattern with well-defined peaks, indicating the presence of crystalline regions within the starch structure. The calculated crystallinity index for this starch is 22%, suggesting that a considerable portion of the starch structure is amorphous. This characteristic significantly influences the physical and functional properties of Huaya starch. The diffraction peaks observed in the XRD pattern of Huaya starch are located at specific 2θ positions. These peaks indicate an A-type crystalline structure, similar to that observed in other plant-based starches. The A-type structure consists of double helices of amylose that pack in an orderly arrangement, forming a crystalline network. The main peaks are observed at 2θ angles of approximately 15°, 17°, 18°, and 23°, which are characteristic of this structure. The crystallinity index of 22% is lower than that of other unconventional starches, such as Colok starch, which has a crystallinity index of 33%. This lower crystallinity suggests that Huaya starch has a higher proportion of amorphous regions, which could affect its thermal behavior and water absorption capacity. Amorphous regions are more susceptible to gelatinization and can provide a greater swelling capacity, which is beneficial in applications requiring high water absorption.
Marta et al. [42] reported similarities with banana starch, which also exhibits an A-type structure and a relatively low crystallinity index [42]. However, the crystallinity of banana starch is slightly higher, which could translate into greater thermal stability and mechanical strength. In food applications, Huaya starch could offer advantages in forming soft and stable gels, suitable for products such as sauces and puddings. Another relevant study is regarding native corn starch, which has a crystallinity index of 27% [43]. Although corn starch exhibits higher crystallinity, Huaya starch may validate greater versatility in applications requiring rapid gelatinization and high water absorption capacity. This characteristic could be advantageous in the food industry and pharmaceutical products, where texture and absorption capacity are critical. Huaya starch can also be compared to taro starch, which has a crystallinity index of 35% [44]. Taro starch shows a more crystalline structure, resulting in higher thermal and mechanical resistance. However, the higher proportion of amorphous regions in Huaya starch could provide greater flexibility and processing capability in industrial applications, such as the manufacturing of bioplastics and biodegradable packaging materials.
The XRD analysis of Ramón starch reveals a diffraction pattern with well-defined peaks indicating a significant crystalline structure. The crystallinity index for this starch is 38%, suggesting a predominance of crystalline regions over amorphous ones. This level of crystallinity is relatively high compared to other unconventional starches, which can influence the thermal and mechanical properties of Ramón starch. The most prominent peaks identified in the diffraction pattern are at 2θ angles of approximately 11°, 15°, 17°, 20°, and 23°, characteristic of an A-type crystalline structure. This structure is common in cereal starches and is associated with the formation of double helices of amylose packed in an orderly arrangement. The high crystallinity of Ramón starch suggests greater thermal stability and resistance to gelatinization, properties beneficial in various industrial applications. The 38% crystallinity index indicates a highly ordered structure, which can enhance the mechanical strength and stability of products formulated with this starch. In the food industry, high crystallinity can translate to a firmer and more stable texture in products like sauces and puddings, where robust gel formation is crucial. Additionally, the crystalline structure can contribute to lower retrogradation during storage, improving the quality and shelf life of food products [45].
Ramón starch shows higher crystallinity than Colok and Huaya starches. Canto-Pinto et al. [46] reported a crystallinity index of 33% for Colok starch and 22% for Huaya starch. These lower crystallinity values suggest that Ramón starch may offer advantages in applications requiring high thermal and mechanical stability. For example, in bioplastic production, a starch with high crystallinity can provide greater rigidity and lower water permeability, desirable in biodegradable packaging. Furthermore, the highly crystalline structure of Ramón starch can influence its rheological behavior and film-forming capacity. Onyeaka et al. [32] found that starches with high crystallinity tend to form stronger films with better barrier properties, crucial in packaging applications. High crystallinity can also reduce the water solubility of the starch, affecting its use in applications requiring rapid dissolution or water absorption.
The X-ray diffraction analysis of Ramón starch reveals a crystallinity index of 38%, highlighting its A-type crystalline structure and predominance of ordered regions. These structural characteristics significantly impact its functional properties and potential applications. Compared to other unconventional starches, Ramón starch offers advantages in terms of thermal and mechanical stability, making it suitable for applications in the food industry and in the production of bioplastics and biodegradable materials. The XRD analysis of Ramón starch suggesting a highly ordered structure with a greater proportion of crystalline regions compared to other unconventional starches. This level of crystallinity is significant as it affects the thermal, mechanical, and functional properties of Ramón starch, making it suitable for various industrial applications. Ramón starch presents an A-type crystalline structure, characterized by prominent peaks at 2θ angles of approximately 11°, 15°, 17°, 20°, and 23°. This pattern is similar to that observed in native corn starch, which also shows an A-type structure with a crystallinity index of 27% [43]. The higher crystallinity of Ramón starch suggests greater thermal stability and superior mechanical strength, beneficial for applications requiring durable and heat-resistant materials.
Marta et al. [42] reported a crystallinity index of 28% to banana starch similar to obtained to Ramon starch. Banana starch, with its lower crystallinity, tends to gelatinize at lower temperatures and has a softer texture. On the other hand, Ramón starch, due to its high crystallinity, can gelatinize at higher temperatures and form firmer gels, desirable in the food industry for products like sauces and puddings. Taro starch, with a crystallinity index of 35% [44], presents a mixed A and B crystalline structure. Although both starches show high crystallinity, differences in crystalline structure can influence their functional properties. Ramón starch, with its predominantly A-type structure, may offer advantages in terms of thermal stability and mechanical resistance, while taro starch may have greater flexibility and less retrogradation. Sago starch, with a crystallinity index of 40% [47], has a complex crystalline structure providing high rigidity and excellent barrier properties. In comparison, Ramón starch, though slightly less crystalline, still offers high thermal and mechanical stability, making it suitable for applications in the production of bioplastics and biodegradable materials. The high crystallinity of Ramón starch reduces its water solubility and increases its moisture resistance, desirable characteristics in packaging materials and coatings.
Parota starch exhibits a crystallinity index of 37%, indicating a highly ordered structure with a significant proportion of crystalline regions. This high crystallinity index suggests that Parota starch possesses superior physical and functional properties, making it suitable for various industrial applications. The well-defined peaks in the XRD pattern of Parota starch are located at 2θ positions of approximately 15°, 17°, 18°, and 23°. These peaks are characteristic of an A-type crystalline structure, commonly found in cereal starches. The A-type structure is characterized by a high density of molecular packing due to the formation of amylose double helices that are compactly packed. Almeida et al. [15] reported a crystallinity index of 30% for quinoa starch, which is lower than the value calculated for Parota starch. The more ordered structure of Parota starch suggests greater thermal and mechanical stability, advantageous for applications in the food industry where firm textures and products that maintain their structural integrity during storage and processing are required. Achira starch (Canna edulis), which displays a crystallinity index of 32% [17], is also compared with Parota starch. Both starches exhibit peaks at similar positions, but Parota starch shows a higher proportion of crystalline regions. This difference can influence gelatinization, where Parota starch might gelatinize at higher temperatures and form more stable and less retrogradable gels, thus improving the shelf life and quality of food products. In another study, mango starch (Mangifera indica) showed a crystallinity index of 34% [48]. Although close to the value of Parota starch, the difference in crystalline structure may result in different functional properties. The higher crystallinity of Parota starch can lead to lower water solubility and higher moisture resistance, which is beneficial for applications in bioplastics and packaging materials where low water permeability is required.
Mung bean starch (Vigna radiata) has a crystallinity index of 29% [49], significantly lower than that of Parota starch. This difference implies that Parota starch has a more rigid and stable structure, which can be advantageous in applications requiring high mechanical and thermal resistance. Additionally, the highly crystalline structure of Parota starch can provide better barrier properties, which are crucial in the food packaging industry. The X-ray diffraction analysis of Parota starch reveals a crystallinity index of 37%, indicating an A-type crystalline structure with well-defined peaks. This highly ordered structure contributes to its thermal and mechanical stability, making Parota starch a promising source for various industrial applications, including food products, bioplastics, and biodegradable packaging materials.