Modified polysaccharides for food packaging applications: A review

Dual-fluorescent starch biopolymer films containing 5-(4-nitrophenyl)-1,3,4-thiadiazol-2-amine powder as a functional nanofiller

Physical and photophysical properties of starch-based biopolymer films containing 5-(4-nitrophenyl)-1,3,4-thiadiazol-2-amine (NTA) powder as a nanofiller were examined using atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), stationary UV-Vis and fluorescence spectroscopy as well as resonance light scattering (RLS) and time-resolved measurements, and where possible, analyzed with reference to pristine NTA solutions. AFM studies revealed that the addition of NTA into the starch biopolymer did not significantly affect surface roughness, with all examined films displaying similar Sq values ranging from 70.7 nm to 79.7 nm. Similarly, Young's modulus measurements showed no significant changes after incorporating the 1,3,4-thiadiazole. Adhesion force and water contact angle assessments demonstrated that the films maintained high hydrophilicity (water wetting) across all examined films. Color analysis corroborated the anticipated trend, showing that increasing additive content resulted in decreased lightness and increased yellowness. Interestingly, however, while in polar isopropanol solvent at low concentration, NTA shows a typical single-band emission, centered at 410 nm and a slight enhancement of the band on the long-wavelength side around 530 nm, its incorporation into the biopolymer matrices results in the appearance of dual fluorescence signal with maxima at 430 and 530 nm. Concentration-dependence emission experiments, demonstrating that with even a slight increase of the amount of NTA in solution, an additional, weak long-wavelength emission band emerged within the spectral range corresponding to the intensive band in the biopolymer film, along with results of the performed quantum-chemical studies, including both the monomeric and aggregated (dimer and trimer) models, conclusively unveil that the dual fluorescence observed in starch/NTA films is due to molecular aggregation effects resulting in aggregation-induced emission. This study underscores the potential of NTA as an additive in biobased polymer films, furnishing them with new photophysical features without substantially altering their surface properties and thus enabling their extended applications.

Development of Sodium Alginate Bioplastic Reinforced with Dried Orange Juice By-Product for Use in Packaging

Pollution caused by nonrenewable plastics has driven the use of natural polymers. Similarly, the disposal of food waste still harms the environment. Considering both aspects, this study aimed to evaluate the effect of incorporating orange by-product powder (OBP) as a reinforcing material into sodium alginate films with glycerol. Sodium alginate-based films were produced using glycerol and various concentrations of OBP. The films were characterized in terms of thickness, color, water content, mechanical properties, light transmission, transparency, X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), contact angle, solubility, swelling, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The addition of OBP significantly (p < 0.05) reduced the water content of the film from 37.75% ± 5.80a (0-OBP) to 24.49% ± 1.47b (45-OBP). The higher the concentration of OBP, the higher the tensile strength of the films, from 7.99 MPa ± 0.91a (0-OBP) to 18 MPa ± 1.38d (45-OBP), and the higher the hydrophobicity, from 57.60° ± 0.41a (0-OBP) to 70.34° ± 0.98c (45-OBP). From TGA and XRD analyses, it was observed that the incorporation of OBP resulted in less crystalline and more thermally resistant materials. Therefore, this study shows that OBP is a promising reinforcing component for sodium alginate films.

Recent Advances in Postharvest Application of Exogenous Phytohormones for Quality Preservation of Fruits and Vegetables

The increasing global population has heightened the demand for food, leading to escalated food production and, consequently, the generation of significant food waste. Factors such as rapid ripening, susceptibility to physiological disorders, and vulnerability to microbial attacks have been implicated as contributing to the accelerated senescence associated with food waste generation. Fruits and vegetables, characterized by their high perishability, account for approximately half of all food waste produced, rendering them a major area of concern. Various postharvest technologies have thus been employed, including the application of phytohormone treatments, to safeguard and extend the storability of highly perishable food products. This review, therefore, explores the physicochemical properties and biological aspects of phytohormones that render them suitable for food preservation. Furthermore, this review examines the effects of externally applied phytohormones on the postharvest physiology and quality attributes of fresh produce. Finally, the review investigates the mechanisms by which exogenous phytohormones preserve food quality and discusses the associated limitations and safety considerations related to the use of these compounds in food applications.

In the process of polysaccharide gel formation: A review of the role of competitive relationship between water and alcohol molecules

Polysaccharides have emerged as versatile materials capable of forming gels through diverse induction methods, with alcohol-induced polysaccharide gels demonstrating significant potential across food, medicinal, and other domains. The existing research mainly focused on the phenomena and mechanisms of alcohol-induced gel formation in specific polysaccharides. Therefore, this review provides a comprehensive overview of the intricate mechanisms underpinning alcohol-triggered gelation of different polysaccharides and surveys their prominent application potentials through rheological, mechanical, and other characterizations. The mechanism underlying the enhancement of polysaccharide network structures by alcohol is elucidated, where alcohol displaces water to establish hydrogen bonding and hydrophobic interactions with polysaccharide chains. Specifically, alcohols change the arrangement of water molecules, and the partial hydration shell surrounding polysaccharide molecules is disrupted, exposing polysaccharides' hydrophobic groups and enhancing hydrophobic interactions. Moreover, the pivotal influences of alcohol concentration and addition method on polysaccharide gelation kinetics are scrutinized, revealing nuanced dependencies such as the different gel-promoting capabilities of polyols versus monohydric alcohols and the critical threshold concentrations dictating gel formation. Notably, immersion of polysaccharide gels in alcohol augments gel strength, while direct alcohol addition to polysaccharide solutions precipitates gel formation. Future investigations are urged to unravel the intricate nexus between the mechanisms underpinning alcohol-induced polysaccharide gelation and their practical utility, thereby paving the path for tailored manipulation of environmental conditions to engineer bespoke alcohol-induced polysaccharide gels.

Accumulation of Hydrogen Bonds and van der Waals Interactions Determines Force Response between Two Parallel Cellulose Chains: Steered Molecular Dynamics Simulations

We investigated the response forces between two parallel cellulose chains during the shearing and tearing processes by using steered molecular dynamics simulations. It was found that there are two logarithmic dependencies between response force and pulling speed in shearing processes but only one in tearing, according to Bell's equation by fitting the f-ln v curve. The mechanism is that there are 2-fold interactions determining the force response between two parallel cellulose chains resisting chain separation during a shearing process. Our results indicate that hydrogen bonds dominate the interchain interactions in the fast pull mode (FPM) for shearing, while van der Waals interactions dominate in the slow pull mode (SPM). For tearing, the one-by-one breaking of hydrogen bonds and van der Waals interactions plays a main role.

Food-packaging applications and mechanism of polysaccharides and polyphenols in multicomponent protein complex system: A review

With the increasingly mature research on protein-based multi-component systems at home and abroad, the current research on protein-based functional systems has also become a hot spot and focus in recent years. In the functional system, the types of functional factors and their interactions with other components are usually considered to be the subjective factors of the functional strength of the system. Because this process is accompanied by the transfer of protons and electrons in the system, it has antioxidant, antibacterial and anti-inflammatory properties. Polyphenols and polysaccharides have the advantages of wide source, excellent functionality and good compatibility with proteins, and have become excellent and representative functional factors. However, polyphenols and polysaccharides are usually accompanied by poor stability, poor solubility and low bioavailability when used as functional factors. Therefore, the effect of separate release and delivery will inevitably lead to non-significant or direct degradation. After forming a multi-component composite system with the protein, the functional factor will form a stable system driven by hydrogen bonds, hydrophobic forces and electrostatic forces between the functional factor and the protein. When used as a delivery system, it will protect the functional factor, and when released, through the specific recognition of the cell membrane receptor signal, the effect of fixed-point delivery is achieved. In addition, this multi-component composite system can also form a functional composite film by other means, which has a long-term significance for prolonging the shelf life of food and carrying out specific antibacterial.

Avocado seed starch utilized in eco-friendly, UV-blocking, and high-barrier polylactic acid (PLA) biocomposites for active food packaging applications

Efficient and effective use of biopolymers, such as starch, has increasingly prompted interest due to the current environmental challenges. However, starch-based composites still show poor ductility along with water and oxygen permeability, which may not meet the requirements for food packaging standards. In this study, modified starch (m-St), isolated from the avocado seed and synthesized with tert-butyl acetoacetate (t-BAA), was embedded into polylactic acid (PLA) to design new eco-friendly composites. The developed biocomposites were found to exhibit high performance with outstanding mechanical properties in conjunction with remarkable light, water vapor, and oxygen blocking features for food packaging applications. PLA/m-St(1:6) 20 wt% composites showed a dramatic increase in elongation at break (EB%) from 3.35 to 27.80 % (about 730 % enhancement) and exhibited remarkable UV-blocking performance from 16.21 to 83.86 % for UVB, relative to pure PLA. Equally importantly, these biocomposites revealed significant improvement in oxygen and water vapor barrier performance by reducing their values from 1331 to 32.9 cc m-2 day-1 (indicating a remarkable reduction of 97.53 %) and 61.9 to 28 g m-2 day-1, respectively. This study can show the great potential of extracting starch from biowaste resources and transforming it into sustainable bio-based composites as a promising solution for food packaging applications.

Plant polysaccharides extracted by high pressure: A review on yields, physicochemical, structure properties, and bioactivities

Polysaccharides are biologically essential macromolecules, widely exist in plants, which are used in food, medicine, bioactives' encapsulation, targeted delivery and other fields. Suitable extraction technology can not only improve the yield, but also regulate the physicochemical, improve the functional property, and is the basis for the research and application of polysaccharide. High pressure (HP) extraction (HPE) induces the breakage of raw material cells and tissues through rapid changes in pressure, increases extraction yield, reduces extraction time, and modifies structure of polysaccharides. However, thus far, literature review on the mechanism of extraction, improved yield and modified structure of HPE polysaccharide is lacking. Therefore, the present work reviews the mechanism of HPE polysaccharide, increasing extraction yield, regulating physicochemical and functional properties, modifying structure and improving activity. This review contributes to a full understanding of the HPE or development of polysaccharide production and modification methods and promotes the application of HP technology in polysaccharide production.