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.

Effect of soybean polysaccharide and soybean oil on gelatinization and retrogradation properties of corn starch.

This investigation stems from the wide interest in mitigating starch retrogradation, which profoundly impacts the quality of starch-based food, garnering significant attention in the contemporary food industry. Our study delves into the intricate dynamics of soluble soybean polysaccharide (SSPS) and soybean oil (SO) when added individually or in combination to native corn starch (NCS), offering insights into the gelatinization and retrogradation phenomena. We observed that SSPS (0.5 %, w/w) hindered starch swelling, leading to an elevated gelatinization enthalpy change (∆H) value, while SO (0.5 %, w/w) increased ∆H due to its hydrophobicity. Adding SSPS and/or SO concurrently reduced the viscosity and storage modulus (G') of starch matrix. For the starch gel (8 %, w/v) after refrigeration, SSPS magnified water-holding capacity (WHC) and decreased hardness through hydrogen bonding with starch, while SO increased hardness with limited water retention. Crucially, the combination of SSPS and SO maximized WHC, minimized hardness, and significantly inhibited starch retrogradation. The specific ratio of SSPS to SO was found to significantly influence the starch properties, with a 1:1 ratio resulting in the most desirable quality for application in starch-based foods. This study offers insights for utilizing polysaccharides and lipids in starch-based food products to extend shelf life.

Combined effect of heat moisture and ultrasound treatment on the physicochemical, thermal and structural properties of new variety of purple rice starch.

The advantages of physically modifying starch are evident: minimal environmental impact, no by-products, and straightforward control. The impact of dual modification on starch properties is contingent upon modification conditions and starch type. Herein, we subjected purple rice starch (PRS) to heat-moisture treatment (HMT, 110 °C, 4 h) with varying moisture content, ultrasound treatment (UT, 50 Hz, 30 min) with different ultrasonic power, and a combination of HMT and UT. Our findings reveal that UT following HMT dispersed starch granules initially aggregated by HMT and resulted in a rougher granule surface. Rheological analysis showcased a synergistic effect of HMT and UT, enhancing the fluidity of PRS and reinforcing its resistance to deformation in paste form. The absorbance ratio R1047/1015 indicates that increased moisture content during HMT and high ultrasound power for UT reduced the short-range order degree (1.69). However, the combined HMT-UT exhibited an increased R1047/1015 (1.38-1.64) compared to HMT alone (1.29-1.45), likely due to short-chain rearrangement. Notably, the A-type structure of PRS remained unaltered, but overall crystallinity significantly decreased (23.01 %-28.56 %), consistent with DSC results. In summary, physical modifications exerted significant effects on PRS, shedding light on the mechanisms governing the transformation of structural properties during HMT-UT.

Purple rice starch in wheat: Effect on retrogradation dependent on addition amount.

While individual starch types may not possess the ideal gelatinization and retrogradation properties for specific applications, the amalgamation of multiple starch varieties might bestow desirable physicochemical properties upon resulting starch-based products. This study explored the impact of incorporating purple rice starch (PRS), as a novel starch variant (up to 15 % PRS), on the gelatinization and retrogradation (within 14 days) of regular wheat starch (WS). Rheological and texture assessments demonstrated that the introduction of PRS diminished the viscoelasticity and hardness of fresh WS paste. Additionally, in the case of retrograded WS pastes stored at 4 °C for 1-14 days, the incorporation of 10 % or 15 % PRS effectively retarded the reduction in transparency and significantly reduced hardness, retrogradation degree, the ratio of absorbance at 1047/1017 cm-1, and relative crystallinity. Notably, 10 % PRS results in a more pronounced effect. Conversely, 5 % PRS induced an opposing impact on retrograded WS post-storage. Moreover, scanning electron microscopy revealed that as the proportion of PRS increased, the microstructure of gelatinized WS-PRS closely resembled that of pure PRS. In conclusion, the diverse effects of varying PRS proportions on WS alter the texture and characteristics of starch-based foods, underscoring the potential of starch blending for improved applications.

Phenotypic quantification of root spatial distribution along circumferential direction for field paddy-wheat.

Plant roots are essential for water and nutrient absorption, anchoring, mechanical support, metabolite storage and interaction with the surrounding soil environment. A comprehensive understanding of root traits provides an opportunity to build ideal roots architectural system that provides improved stability and yield advantage in adverse target environments caused by soil quality degradation, climate change, etc. However, we hypothesize that quantitative indicators characterizing root system are still need to be supplemented. Features describing root growth and distribution, until now, belong mostly to 2D indicators or reflect changes in the root system with a depth of soil layers but are rarely considered in a spatial region along the circumferential direction. We proposed five new indicators to quantify the dynamics of the root system architecture (RSA) along its eight-part circumferential orientations with visualization technology which consists of in-situ field root samplings, RSA digitization, and reconstruction according to previous research based on field experiments that conducted on paddy-wheat cultivation land with three fertilization rates. The experimental results showed that the growth space of paddy-wheat root is mainly restricted to a cylinder with a diameter of 180 mm and height of 200 mm at the seedlings stage. There were slow fluctuating trends in growth by the mean values of five new indicators within a single volume of soil. The fluctuation of five new indicators was indicated in each sampling time, which decreased gradually with time. Furthermore, treatment of N70 and N130 could similarly impact root spatial heterogeneity. Therefore, we concluded that the five new indicators could quantify the spatial dynamics of the root system of paddy-wheat at the seedling stage of cultivation. It is of great significance to the comprehensive quantification of crop roots in targeted breeding programs and the methods innovation of field crop root research.

Study on hydroxypropyl corn starch/alkyl ketene dimer composite film with enhanced water resistance and mechanical properties.

This study aimed to address the limited applicability of starch-based films in food packaging due to their inherent hydrophilicity, by developing a highly hydrophobic and mechanically reinforced film through compositing with alkyl ketene dimer (AKD). The FTIR analysis confirmed the successful introduction of AKD into the starch backbone via esterification by forming a ß-keto ester linkage. Notably, the incorporation of AKD resulted in significant improvements in the modified film (S80A20), by exhibiting a higher water contact angle (WCA) of 128.28° and a reduced water vapor permeability (WVP) to 0.81×10-10 (g m/m2 s Pa). These enhancements were attributed to the inherent low surface energy of AKD and the increased surface roughness caused by AKD recrystallization. Moreover, the mechanical properties of the films were also enhanced due to the chemical crosslinking and intermolecular hydrogen bonding, as supported by the results of relaxation temperatures and molecular dynamics simulations. Considering the environmentally friendly and biodegradable nature of all components, the prepared hydrophobic films will hopefully be applied in food packaging.

Harnessing nitrogen-doped graphene quantum dots for enhancing the fluorescence and conductivity of the starch-based film.

The flexible film is widely applied in the modern electronic industry, whilst it is still challenging to use biopolymer substrates (e.g., starch) to prepare flexible film well-performed in conductivity and fluorescence. In the study, a novel conductive, fluorescent, and flexible biopolymer film was prepared via a cost-effective method by fabricating the nitrogen-doped oxide-reduced graphene quantum dots (N-rGO-QDs) into the thermoplastic starch (TPS) substrate. TPS/N-rGO-QDs film with 10 wt% N-rGO-QDs showed the desirable lowest resistivity (0.082 Ω·m), acceptable light transmittance (60-80 %), and durable fluorescence intensity (9000 CPS). The results reveal a novel starch-based multifunctional film with satisfactory electrical and fluorescent performances, which is hypothesized potential to be applied in some frontier domains, like human wearable devices.

Improved hydrophobicity, antibacterial and mechanical properties of polyvinyl alcohol/quaternary chitosan composite films for antibacterial packaging.

Polyvinyl alcohol (PVA) and chitosan (CS) are attractive polymeric feedstocks for developing eco-environmental materials. In this work, a biodegradable and antibacterial film was developed based on PVA blending with different long-chain alkyl and different contents of quaternary chitosan through solution casting, in which quaternary chitosan not only acted as an antibacterial agent but also improved hydrophobicity and mechanical properties. A novel peak appeared at 1470 cm-1 in Transform Infrared Spectroscopy (FTIR) and a new CCl bond spectral peak at 200 eV in X-ray photoelectron spectroscopy (XPS) spectra suggested that CS was successfully modified by quaternary. Besides, the modified films have better antibacterial effects against Escherichia (E. coli) and Staphylococcus (S. aureus) and present stronger antioxidant properties. Optical properties demonstrated that the light transmittance on both UV and visible light showed a decreasing trend with the increase of the quaternary chitosan contents. Whereas the composite films have enhanced hydrophobicity than PVA film. Furthermore, the composite films had higher mechanical properties, in which Young's modulus, tensile strength, and elongation at break were 344.99 MPa, 39.12 MPa, and 507.09 %, respectively. This research demonstrated that the modified composite films could extend the shelf of life on antibacterial packaging.

Chitosan-Gelatin Films: Plasticizers/Nanofillers Affect Chain Interactions and Material Properties in Different Ways.

Biopolymers, which are biodegradable and inherently functional, have high potential for specialized applications (e.g., disposable and transient systems and biomedical treatment). For this, it is important to create composite materials with precisely defined chain interactions and tailored properties. This work shows that for a chitosan-gelatin material, both glycerol and isosorbide are effective plasticizers, but isosorbide could additionally disrupt the polyelectrolyte complexation (PEC) between the two biopolymers, which greatly impacts the glass transition temperature (Tg), mechanical properties, and water absorption. While glycerol-plasticized samples without nanofiller or with graphene oxide (GO) showed minimal water uptake, the addition of isosorbide and/or montmorillonite (MMT) made the materials hydrolytically unstable, likely due to disrupted PEC. However, these samples showed an opposite trend in surface hydrophilicity, which means surface chemistry is controlled differently from chain structure. This work highlights different mechanisms that control the different properties of dual-biopolymer systems and provides an updated definition of biopolymer plasticization, and thus could provide important knowledge for the future design of biopolymer composite materials with tailored surface hydrophilicity, overall hygroscopicity, and mechanical properties that meet specific application needs.

Morphology and Rheology of a Cool-Gel (Protein) Blended with a Thermo-Gel (Hydroxypropyl Methylcellulose).

This study investigates the morphological and rheological properties of blended gelatin (GA; a cooling-induced gel (cool-gel)) and hydroxypropyl methylcellulose (HPMC; a heating-induced gel (thermo-gel)) systems using a fluorescence microscope, small angle X-ray scattering (SAXS), and a rheometer. The results clearly indicate that the two biopolymers are immiscible and have low compatibility. Moreover, the rheological behavior and morphology of the GA/HPMC blends significantly depend on the blending ratio and concentration. Higher polysaccharide contents decrease the gelling temperature and improve the gel viscoelasticity character of GA/HPMC blended gels. The SAXS results reveal that the correlation length (ξ) of the blended gels decreases from 5.16 to 1.89 nm as the HPMC concentration increases from 1 to 6%, which suggests that much denser networks are formed in blended gels with higher HPMC concentrations. Overall, the data reported herein indicate that the gel properties of gelatin can be enhanced by blending with a heating-induced gel.

Thermomechanically processed chitosan:gelatin films being transparent, mechanically robust and less hygroscopic.

Chitosan and gelatin are attractive polymeric feedstocks for developing environmentally benign, bio-safe, and functional materials. However, cost-effective methods to achieve advantageous materials properties and tailor their functionality are still lacking, but interesting. Herein, we found that physically mixing chitosan and gelatin at 1:1 (w/w) ratio resulted in materials with properties (higher Young's modulus (603.8 MPa) and tensile strength (33.6 MPa), and reduced water uptake (45%) after 6 h of water soaking) better than those of the materials based on mainly chitosan or gelatin. We attribute this synergy to the ionic and hydrogen-bonding interactions between the two biopolymers enabled by high-viscosity thermomechanical processing. Despite the lowest hygroscopicity, the 1:1 chitosan:gelatin films displayed the highest surface hydrophilicity. Besides, addition of gelatin to chitosan led to films being brighter, more transparent and amorphous. Thus, this work has generated new understanding to enhance the application of biopolymers for e.g. packaging, coating, and biomedical applications.

Anchor and bridge functions of APTES layer on interface between hydrophilic starch films and hydrophobic soyabean oil coating.

One of the well-recognized weaknesses of starch-based materials is their sensitivity to moisture, which limits their expanding applications. Natural materials, soyabean oils have been used as a coating for starch film, but the poor interface between hydrophilic starch and hydrophobic soyabean oil needs to be improved. In this work, (3-Aminopropyl) triethoxysilane (APTES) was used to reinforce the bonding between starch matrix and the coating of bio-based acrylated epoxidized soyabean oil (AESO). Study results show that APTES interacted effectively with both starch films via hydrogen bonding, and chemical bonds with AESO through the Michael addition reaction. Pull adhesion and cross-cutting tests demonstrated that the interfacial adhesion was significantly improved after treating their surface with APTES. The interfacial adhesion strength increased over 4 times after treating with 1.6 wt% APTES. The starch films treated with APTES and AESO coating were intact after soaking in water for more than 2 h.

Preparation and characterization of starch/enteromorpha/nano-clay hybrid composites.

Environmentally friendly and biodegradable hybrid composites of starch/enteromorpha/nano-clay were developed. Enteromorpha was used as cheaper filler since it is a waste from marine pollution, while nano-clay acted as a reinforcing agent. The microstructures and performance of these composites were investigated by SEM, DMA, XRD, TGA and tensile testing. Enteromorpha has a hollow tubular thallus structure with very weak mechanical properties, so it is not expected to have the ability to reinforce the starch matrix even though they have very a good interface. However, the granulated fine particles of enteromorpha can mix well with the starch matrix and reduce weak points. Furthermore, the delaminated clay by water and ultrasonic treatment reinforced the mechanical properties of the starch-based materials. The results showed that the hybrid composite containing up to 40% enteromorpha reinforced with nano-clay still has similar or even slightly better mechanical properties compared with pure starch-based materials. Since all components are hydrophilic natural materials, the interfaces between them are very good, and the composites are environmentally friendly and biodegradable.