Fabrication of bio-inspired carbon nanodot-corn starch nanocomposite films via extrusion process for sustainable active food packaging applications.

In this study, carbon nanodot (CD)-corn starch (CS) nanocomposite films are fabricated for active food packaging applications. First, ginkgo biloba leaves (GBL) were used as a biomass-derived carbon precursor, and a facile hydrothermal method was employed to synthesise environmentally sustainable CDs. The GBL-derived carbon nanodots (gCDs) were then characterised and incorporated into a CS matrix via an extrusion process to fabricate the CS/gCD nanocomposite film. The effects of various gCD concentrations on the physicochemical and functional properties of CS/gCD composite films were systematically investigated. The gCD exhibited non-cytotoxic effect against human colorectal adenocarcinoma cell line (Caco-2) cells when exposed up to 1000 µg/mL. The incorporation of gCDs into the CS film improved its mechanical properties, with the toughness of the CS/gCD2% nanocomposite film exhibiting 198 % superiority compared to the CS film. In addition, the oxygen barrier and UV-blocking properties were significantly improved. Furthermore, the CS/gCD nanocomposite film significantly extended the shelf life of ω-3 oils owing to the superior antioxidant activity of the gCDs, exhibiting only 9 meq/kg during the 15-day storage period. Our results suggest that the developed CS/gCD active composite film is a promising candidate for environmentally sustainable solutions to enhance food shelf life and reduce food waste.

Enhancing the Biodegradability, Water Solubility, and Thermal Properties of Polyvinyl Alcohol through Natural Polymer Blending: An Approach toward Sustainable Polymer Applications.

The escalating environmental crisis posed by single-use plastics underscores the urgent need for sustainable alternatives. This study provides an approach to introduce biodegradable polymer blends by blending synthetic polyvinyl alcohol (PVA) with natural polymers-corn starch (CS) and hydroxypropyl methylcellulose (HPMC)-to address this challenge. Through a comprehensive analysis, including of the structure, mechanical strength, water solubility, biodegradability, and thermal properties, we investigated the enhanced performance of PVA-CS and PVA-HPMC blends over conventional polymers. Scanning electron microscopy (SEM) findings of pure PVA and its blends were studied, and we found a complete homogeneity between the PVA and both types of natural polymers in the case of a high concentration of PVA, whereas at lower concentration of PVA, some granules of CS and HMPC appear in the SEM. Blending corn starch (CS) with PVA significantly boosts its biodegradability in soil environments, since adding starch of 50 w/w duplicates the rate of PVA biodegradation. Incorporating hydroxypropyl methylcellulose (HPMC) with PVA not only improves water solubility but also enhances biodegradation rates, as the addition of HPMC increases the biodegradation of pure PVA from 10 to 100% and raises the water solubility from 80 to 100%, highlighting the significant acceleration of the biodegradation process and water solubility caused by HPMC addition, making these blends suitable for a wide range of applications, from packaging and agricultural films to biomedical engineering. The thermal properties of pure PVA and its blends with natural were studied using diffraction scanning calorimetry (DSC). It is found that the glass transition temperature (Tg) increases after adding natural polymers to PVA, referring to an improvement in the molecular weight and intermolecular interactions between blend molecules. Moreover, the amorphous structure of natural polymers makes the melting temperature ™ lessen after adding natural polymer, so the blends require lower temperature to remelt and be recycled again. For the mechanical properties, both types of natural polymer decrease the tensile strength and elongation at break, which overall weakens the mechanical properties of PVA. Our findings offer a promising pathway for the development of environmentally friendly polymers that do not compromise on performance, marking a significant step forward in polymer science's contribution to sustainability. This work presents detailed experimental and theoretical insights into novel polymerization methods and the utilization of biological strategies for advanced material design.

Effect of Glycerol and Sisal Nanofiber Content on the Tensile Properties of Corn Starch/Sisal Nanofiber Films.

Currently, petroleum-derived plastics are widely used despite the disadvantage of their long degradation time. Natural polymers, however, can be used as alternatives to overcome this obstacle, particularly cornstarch. The tensile properties of cornstarch films can be improved by adding plant-derived nanofibers. Sisal (Agave sisalana), a very common low-cost species in Brazil, can be used to obtain plant nanofibers. The goal of this study was to obtain sisal nanofibers using low concentrations of sulfuric acid to produce thermoplastic starch nanocomposite films. The films were produced by a casting technique using commercial corn starch, glycerol, and sisal nanofibers, accomplished by acid hydrolysis. The effects of glycerol and sisal nanofiber content on the tensile mechanical properties of the nanocomposites were investigated. Transmission electron microscopy findings demonstrated that the lowest concentration of sulfuric acid produced fibers with nanometric dimensions related to the concentrations used. X-ray diffraction revealed that the untreated fibers and fibers subjected to acid hydrolysis exhibited a crystallinity index of 61.06 and 84.44%, respectively. When the glycerol and nanofiber contents were 28 and 1%, respectively, the tensile stress and elongation were 8.02 MPa and 3.4%. In general, nanocomposites reinforced with sisal nanofibers showed lower tensile stress and higher elongation than matrices without nanofibers did. These results were attributed to the inefficient dispersion of the nanofibers in the polymer matrix. Our findings demonstrate the potential of corn starch nanocomposite films in the packaging industry.

Effects of fatty acids and glycerides on the structure, cooking quality, and in vitro starch digestibility of extruded buckwheat noodles.

This study aimed to explore the effects of various lipids on the structure, cooking quality, and in vitro starch digestibility of extruded buckwheat noodles (EBNs) with and without 20% high-amylose corn starch (HACS). Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction revealed that lauric acid bound more strongly to starch than did stearic acid and oleic acid, and the binding capacity of fatty acids with starch was stronger than that of glycerides. The presence of HACS during extrusion facilitated increased formation of starch-lipid complexes. Evaluations of cooking quality and digestion characteristics showed that EBNs containing 20% HACS and 0.5% glycerol monooleate demonstrated the lowest cooking loss (7.28%), and that with 20% HACS and 0.5% oleic acid displayed the lowest predicted glycemic index (pGI) (63.54) and highest resistant starch (RS) content (51.64%). However, excessive starch-lipid complexes were detrimental to EBNs cooking quality and the resistance of starch to digestive enzymes because of the damage to the continuity of the starch gel network. This study establishes a fundamental basis for the development of EBNs with superior cooking quality and a relatively lower GI.

Effects of alginate synergized with polyphenol compounds on the retrogradation properties of corn starch.

This study aimed to investigate the impact of alginate (AG) on the retrogradation properties of corn starch (CS) in conjunction with three phenolic compounds, including naringin (NA), rutin (RT), and soy isoflavones (SI). The findings indicated that AG, NA, RT, and SI collectively resulted in a significant reduction in the hardness, retrogradation enthalpy, and relaxation time of CS gel. This effect was more pronounced when compared to NA, RT, and SI individually. The findings suggested that the elemental system comprising AG, phenolic compounds, and CS yielded enhanced water retention capacity and thermal stability. Moreover, a noticeable decrease in the short-range ordered structure and crystallinity was observed, indicating that AG and phenolic compounds effectively inhibited the retrogradation of CS; notably, the synergistic interaction between AG and SI resulted in the most favorable outcome. The results of this study provide new ideas for the design, development, and quality improvement of starch-based food.

Insight into the mechanism of digestibility inhibition by interaction between corn starch with different gelatinization degree and water extractable arabinoxylan.

On the basis of revealing the interaction mechanism between corn starch (CS) and water-extractable arabinoxylan (WEAX) with high/low molecular weight (H-WEAX, L-WEAX), the degree of gelatinization (DG) on structural behaviors and in vitro digestibility of CS-WEAX complexes (CS/H, CS/L) was evaluated. With the increased DG from 50 % to 95 %, the water adsorption capacity of CS/L was increased 64 %, 58 %, 47 %, which were higher than that of CS/H (39 %, 54 %, 33 %). The gelatinization of starch was inhibited by WEAX, resulting in the enhancement of crystallinity, short-range ordered structure and molecular size of CS-WEAX complexes. Stronger interaction was detected in CS/L than with CS/H as proved by the increased hydrogen bonds and electrostatic force. Complexes exhibited higher resistant starch content (RS) at diverse DG, especially for CS/L. Notability, RS content of samples with 50 % DG were increased from 27.72 % to 32.89 % (CS/H), 36.96 % (CS/L). Except for the reduction of gelatinization degree by adding WEAX, the other possible mechanisms of retarding digestibility were explained as the small steric hindrance of L-WEAX promoted encapsulation of starch granules, limiting enzyme accessibility. Additionally, the fragmentation of CS granules with high DG promoted the movement of H-WEAX, reducing the difference in digestibility compared to CS/L.

Effect of ultrasound/CaCl2 co-treatment on the microstructure, gelatinization, and film-forming properties of high amylose corn starch.

The effect of ultrasound/CaCl2 co-treatment on aggregation structure, thermal stability, rheological, and film properties of high amylose corn starch (HACS) was investigated. The scanning electron microscopy (SEM) images revealed the number of starch fragments and malformed starch granules increased after co-treatment. The differential scanning calorimetry (DSC) results showed the co-treated HACS got a lower gelatinization temperature (92.65 ± 0.495 °C) and enthalpy values (ΔH, 4.14 ± 0.192 J/g). The optical microscope images indicated that lesser Maltase crosses were observed in co-treated HACS. The results of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) indicated ultrasound influenced the compactness of amorphous zone and CaCl2 damaged the crystalline region of HACS granules. Additionally, the rheology properties of HACS dispersion demonstrated the apparent viscosity of co-treated dispersion increased as the ultrasound time prolonged. The mechanical strength and structural compactness of HACS films were improved after ultrasound treatment. The mechanism of ultrasound/CaCl2 co-treatment improved the gelatinization and film-forming ability of HACS was that (i) ultrasound wave loosened the HACS granules shell, promoted the treatment of CaCl2 on HACS granules, and (ii) ultrasound wave improved the uniform distribution of HACS dispersion, increased the interaction between CaCl2 and starch chains during the process of film-forming.

Novel strategy for optimizing of corn starch-based ink food 3D printing process: Printability prediction based on BP-ANN model.

Although starch has been intensively studied as a raw material for 3D printing, the relationship between several important process parameters in the preparation of starch gels and the printing results is unclear. In this study, the relationship between different processing conditions and the gel printing performance of corn starch was evaluated by printing tests, rheological tests and low-field nuclear magnetic resonance (LF-NMR) tests, and a back-propagation artificial neural network (BP-ANN) model for predicting gel printing performance was developed. The results revealed that starch gels exhibited favorable printing performance when the gelatinization temperature ranged from 75 °C to 85 °C, and the starch content was maintained between 15 % and 20 %. The R2adj of the BP-ANN models were all reached 0.894, which indicated good predictive ability. The results of the study not only provide theoretical support for the application of corn starch gels in 3D food printing, but also present a novel approach for predicting the printing performance of related materials. This method contributes to the optimization of printing parameters, thereby enhancing printing efficiency and quality.

Differences and Mechanism of Waxy Corn Starch and Normal Corn Starch in the Preparation of Recrystallized Resistant Starch (RS3).

This study prepared resistant starch (RS) from waxy corn starch and normal corn starch and analyzed the effects of its molecular and microstructural characteristics on RS content. The RS content of waxy corn resistant starch (RS-WCS) was highest at 57.8%, whereas that of normal corn resistant starch (RS-NCS) was 41.46%. The short-chain amylose contents of RS-WCS and RS-NCS were 47.08% and 37.24%, respectively, proportional to their RS content. Additionally, RS content positively correlated with crystallinity, short-range order degree, and degree of polymerization (DP), exceeding 25. Electron microscopic images, before and after enzymolysis, revealed that RS-WCS was hydrolyzed from the surface to the center by pancreatic α-amylase, while RS-NCS underwent simultaneous hydrolysis at the surface and center. These results indicate that the higher RS content in RS-WCS, compared to RS-NCS, is attributable to the synergistic effects of molecular structure and microstructure.

Edible colorimetric label based on immobilized purple sweet potato anthocyanins onto edible film for packaged mushrooms freshness monitoring.

An edible colorimetric label has been developed to determine the freshness level of mushrooms, i.e. white oyster mushrooms (Pleurotus ostreatus). The edible indicator label has been fabricated based on purple sweet potato (Ipomoea batatas L.) anthocyanins (PSPA) immobilized onto an edible film made of chitosan and cornstarch with added PVA. The freshness parameters of the mushrooms were pH, weight loss, texture, and sensory evaluation. The results showed that the colorimetric label was dark purple when the mushroom was fresh, and turn to light purple when the mushroom was still fresh, and finally green when the mushroom was no longer fresh. The color value (mean Red) of the label was measured using the ImageJ program, where its color value (mean Red) increased with decreasing freshness level of the mushrooms. The edible label can distinguish fresh mushrooms from spoilage, making it suitable to be used in a packaged mushroom as a freshness indicator.

Changes in the properties of the corn starch glycerol film in a time-dependent manner during gelatinization.

This study aimed to investigate the fundamental properties, solubility, mechanical properties, barrier performance, and microstructural features of films composed of corn starch and glycerol. Changes in the microstructure were analyzed to understand how they relate to the physical and chemical properties of these films. Specifically, we found that increasing the gelatinization time decreased the film thickness, solubility, water vapor permeability, and maximum degradation temperature and increased the water content. A gradual increase in the water contact angle of the corn starch-glycerol films was observed with increasing gelatinization time. This trend is likely due to the disruptive effect of gelatinization on the crystalline and amorphous structures inherent in corn starch, resulting in reduced film crystallinity, degree of order (DO) and degree of double helix (DD).

Effects of adding proteins from different sources during heat-moisture treatment on corn starch structure, physicochemical and in vitro digestibility.

Proteins impact starch digestion, but the specific mechanism under heat-moisture treatment remains unclear. This study examined how proteins from various sources-white kidney bean, soybean, casein, whey-altered corn starch's structure, physicochemical properties, and digestibility during heat-moisture treatment (HMT). HMT and protein addition could significantly reduce starch's digestibility. The kidney bean protein-starch complex under HMT had the highest resistant starch at 19.74 %. Most proteins effectively inhibit α-amylase, with kidney bean being the most significantly (IC50 = 1.712 ± 0.085 mg/mL). HMT makes starch obtain a more rigid structure, limits its swelling ability, and reduces paste viscosity and amylose leaching. At the same time, proteins also improve starch's short-range order, acting as a physical barrier to digestion. Rheological and low-field NMR analyses revealed that protein enhanced the complexes' shear stability and water-binding capacity. These findings enrich the understanding of how proteins from different sources affect starch digestion under HMT, aiding the creation of nutritious, hypoglycemic foods.

Insight into Rheological Properties and Structure of Native Waxy Starches: Cluster Analysis Grouping.

Recent interest in the use of waxy starches in food production is due to the possibility of replacing chemically modified starches as texture-forming agents with native starch analogues. However, there is a lack of a coherent research comparing different varieties of commercially available waxy starches with respect to their molecular and functional properties. Therefore, the objective of this study was to compare native waxy starches from potatoes, corn, and rice, with particular attention to rheological characteristics in relation to molecular structure. The investigated potato, corn, and rice starch preparations were characterized by significantly different molecular properties due to both botanical origin of starch and variety. The molecular weights of waxy starches were significantly higher than those of their normal counterparts. This phenomenon was accompanied by a more loose conformation of the waxy starch macromolecule in solution. The presence of amylose confers the ability to coagulate starch sol into gel, resulting in substantial changes in the rheological properties of starch paste, and waxy starch pastes being characterized by more viscous flow and smoother texture. Hierarchical cluster analysis indicated that differences between functional properties are more notable for normal than for waxy preparations, in which potato starch, regardless of its variety, was characterized by the most unique characteristics.

Enhancing mechanical and water barrier properties of starch film using chia mucilage.

Biodegradable packaging materials are increasingly being investigated due to rising concerns about food safety and environmental conservation. This study examines the incorporation of chia mucilage (CM) into starch-based films using the casting method, aiming to understand its effects on the structure and functionality of the films. CM, an anionic heteropolysaccharide, is hypothesized to enhance the mechanical and barrier properties of the films through polymer interactions and hydrogen bonding. Our findings confirm that CM incorporation results in films with uniformly smooth surfaces, indicating high compatibility and homogeneity within the starch matrix. Notably, CM improves film transparency and crystallinity. Mechanical assessments show a remarkable elevation in tensile strength, soaring from 5.21 MPa to 12.38 MPa, while elongation at break decreases from 61.73 % to 31.42 %, indicating a trade-off between strength and flexibility. Additionally, water solubility decreases from 57.97 % to 41.40 %, and water vapor permeability is reduced by 30 % with CM loading. These results highlight the role of CM in facilitating the formation of a dense, interconnected polymeric network within the starch matrix. Given the soluble dietary fiber nature of CM, the CS/CM (corn starch/chia mucilage) blended films are expected to be safe for food packaging and applicable as edible films with health benefits.

Characteristics of corn starch/polyvinyl alcohol composite film with improved flexibility and UV shielding ability by novel approach combining chemical cross-linking and physical blending.

With the aim of effectively improving the performance of bio-friendly food packaging and circumventing the hazards associated with petroleum-based plastic food packaging, composite films of corn starch and polyvinyl alcohol were prepared using a new method that involved chemical cross-linking of glutaraldehyde and blending with cinnamon essential oil nanoemulsion (CNE). Glutaraldehyde and CNE enhance the film's network structure by chemical bonding and hydrogen bonding, respectively. This results in improved surface smoothness, mechanical properties, and UV shielding ability of the film. However, the films' surface hydrophilicity increased as a result of CNE, which is harmful for food preservation in high humidity. Overall, glutaraldehyde and CNE have a synergistic effect on some of the properties of the film which is mainly attributed to the films' structure improvement. The films have great potential for preparing flexible and UV-shielding films and offer new ideas for developing biodegradable films.

Effects of plasma-activated water combined with ultrasonic treatment of corn starch on structural, thermal, physicochemical, functional, and pasting properties.

In this study, corn starch was used as the raw material, and modified starch was prepared using a method combining plasma-activated water and ultrasound treatment (PUL). This method was compared with treatments using plasma-activated water (PAW) and ultrasound (UL) alone. The structure, thermal, physicochemical, pasting, and functional properties of the native and treated starches were evaluated. The results indicated that PAW and UL treatments did not alter the shape of the starch granules but caused some surface damage. The PUL treatment increased the starch gelatinization temperature and enthalpy (from 11.22 J/g to 13.13 J/g), as well as its relative crystallinity (increased by 0.51 %), gel hardness (increased by 16.19 %) compared to untreated starch, without inducing a crystalline transition. The PUL treatment resulted in a whitening of the samples. The dual treatment enhanced the thermal stability of the starch paste, which can be attributed to the synergistic effect between PAW and ultrasound (PAW can modify the starch structure at a molecular level, while ultrasound can further disrupt the granule weak crystalline structures, leading to improved thermal properties). Furthermore, FTIR results suggested significant changes in the functional groups related to the water-binding capacity of starch, and the order of the double-helical structure was disrupted. The findings of this study suggest that PUL treatment is a promising new green modification technique for improving the starch structure and enhancing starch properties. However, further research is needed to tailor the approach based on the specific properties of the raw material.

Effect of polyphenols from Ascophyllum nodosum seaweeds on the rheology and digestion of corn starch gels and gluten-free bread features.

The main objective of this work is to study the effect of polyphenols, from the brown seaweed Ascophyllum nodosum, on the structure and digestion behaviour of gels at two corn starch concentrations (1.95 and 5.00% w/w) as well as the structure, color and texture features of crumbs from gluten-free breads. Adsorption isotherms of polyphenols on native and gelled starches were carried out and modelled by means of Langmuir and Henry models, respectively. The formation and characteristics of tested gels were rheologically monitored by means of heating ramp, time sweep at high temperature, cooling ramp and frequency sweep at 25 °C. Elastic modulus values decreased with the presence of polyphenols. Additionally, the polyphenols significantly decreased the digestion rate, measured by both chemical and rheological procedures, and the final concentration of digested starch. Finally, the presence of polyphenols in breads increased the hardness and chewiness values and decreased the cohesiveness and resilience values as well as the crumb hardening during storage.

Jute fibre reinforced biodegradable composites using starch as a biological macromolecule: Fabrication and performance evaluation.

The aim of this study is to develop environment friendly packaging and life style materials for replacing conventionally explored hazardous synthetic materials. The study carried out by using raw jute fibre reinforced thermoplastic corn starch (TPCS) is to develop biodegradable flexible composite materials. Flexible composites are prepared by maintaining with different fibre content (30 %, 40 % and 50 wt%). A thin coating of polyurethane based formulation is applied on one side of the developed composite to make it water resistant. Composite samples are examined in terms of their tensile properties, tear resistance, folding endurance, water absorbency, capillary action etc. The results show that flexible composites, having 50 % fibre content have tensile strength of 12.8 MPa and 12 MPa at cross and machine direction respectively compared to 3.1 MPa for the TPCS film. The Water drop test on the coated side of the developed material concluded that there is no water penetration even after 60 min of wetting. The interaction between two hydrophilic components is established with FTIR analysis. The XRD analysis was carried out to find the crystallinity of TPCS, Jute fibre and composite samples. Surface morphology and fibre/matrix interaction is observed by SEM. The detail chemical mechanism involved of fibre matrix interaction also been postulated. The scientific finding shows that the developed flexible material can be suitable for making packaging and life style items.

Coumarin-Modified Starch Fluorescent Nanoparticles as Sensor of Fe3+ and Zn2+ ions Utilizing Dynamic Quenching and Chelation Mechanisms.

Zinc and iron are two essential trace minerals that play a pivotal role in maintaining optimal health and well-being in the human body. Despite being required in relatively small quantities, their significance can be understated as they participate in a wide array of critical physiological processes such as oxygen transport, DNA synthesis, controlling nutrient availability, etc. Understanding the distribution and behavior of these ions in natural water bodies is essential for assessing water quality, studying ecological processes, and managing environmental impacts. In this study, we have developed a dual fluorescence probe using starch which was functionalized with coumarin derivatives, for efficient detection of Fe3+ and Zn2+ ions. This structure led a self-assembled starch/coumarin (SC) fluorescent nanoparticles with strong fluorescence intensity under ultraviolet light (365 nm). The quenching effect of Fe3+ on the SC fluorescent probe enabled efficient specific detection of Fe3+. Furthermore, Zn2+ ions increased fluorescence intensity of coumarin compounds (λemission = 459). This phenomenon occurs when the coumarin compound forms a complex or interacts with the zinc ion, resulting in enhanced fluorescence emission. In summary, the developed fluorescent probe offered a promising approach for sensitive and specific detection of iron and zinc ions in aqueous solutions.

Glass bead system to study mycotoxin production of Aspergillus spp. on corn and rice starches.

Mycotoxin production by aflatoxin B1 (AFB1) -producing Aspergillus flavus Zt41 and sterigmatocystin (ST) -hyperproducer Aspergillus creber 2663 mold strains on corn and rice starch, both of high purity and nearly identical amylose-amylopectin composition, as the only source of carbon, was studied. Scanning electron microscopy revealed average starch particle sizes of 4.54 ± 0.635 µm and 10.9 ± 2.78 µm, corresponding to surface area to volume ratios of 127 1/µm for rice starch and 0.49 1/µm for corn starch. Thus, a 2.5-fold difference in particle size correlated to a larger, 259-fold difference in surface area. To allow starch, a water-absorbing powder, to be used as a sole food source for Aspergillus strains, a special glass bead system was applied. AFB1 production of A. flavus Zt41 was determined to be 437.6 ± 128.4 ng/g and 90.0 ± 44.8 ng/g on rice and corn starch, respectively, while corresponding ST production levels by A. creber 2663 were 72.8 ± 10.0 µg/g and 26.8 ± 11.6 µg/g, indicating 3-fivefold higher mycotoxin levels on rice starch than on corn starch as sole carbon and energy sources. KEY POINTS: • A glass bead system ensuring the flow of air when studying powders was developed. • AFB1 and ST production of A. flavus and A. creber on rice and corn starches were studied. • 3-fivefold higher mycotoxin levels on rice starch than on corn starch were detected.