Improving structural and functional properties of starch-catechin-based green nanofiber mats for active food packaging by electrospinning and crosslinking techniques.

The hydrophilic and low mechanical properties limited the application of starch-based films. In this work, a hydrophobic starch-based nanofiber mat was first successfully prepared from aqueous solution at room temperature by using electrospinning and glutaraldehyde (GTA) vapor phase crosslinking techniques for active packaging applications. Catechin (CAT) was immobilized in the nanofibers by electrospinning, resulting in higher thermal stability (Tdmax = 315.23 °C), antioxidant (DPPH scavenging activity = 94.31 ± 2.70 %) and antimicrobial (inhibition zone diameter = 15.6 ± 0.3 mm) of the fibers, which further demonstrated hydrogen bonding and electrostatic interaction between CAT and fibers. Nanofibers after GTA vapor phase crosslinking exhibited enhanced hydrophobicity (water contact angle: 15.6 ± 1.5° â†’ 93.5 ± 2.3°) and mechanical properties (tensile strength: 1.82 ± 0.06 MPa â†’ 7.64 ± 0.24 MPa, elastic modulus: 19.35 ± 0.63 MPa â†’ 45.34 ± 0.51 MPa). The results demonstrated that preparation of starch-based electrospun nanofiber mats in aqueous system at room temperature overcame the challenges of organic solvent pollution and thermosensitive material encapsulation, while GTA vapor phase crosslinking technique improved the hydrophobicity and mechanical properties of nanofiber mats, which facilitated the application of starch-based materials in the field of packaging.

Effect of mixture microstructure/compatibility on the properties of type-A gelatin-dextran edible films.

The influence of phase separation behavior on bio-based film properties has attracted more and more attention. This work investigated the effects of microstructure and compatibility of the type-A gelatin (GE)-dextran (DE) mixtures on GE-DE edible film properties. Three kinds of GE-DE edible films with different textures were prepared via modulating the microstructure and compatibility of film-forming mixtures using the method of gelation-drying, e.g., homogeneous films, microphase separated films with relatively homogeneous texture, and microphase separated films with uneven texture. The optical, mechanical, water barrier, and thermal properties of films were characterized. Results showed that microstructure and compatibility significantly affected the film properties. In general, films with DE-in-GE microstructure exhibited the best film properties, followed by films with water-in-water-in-water/bicontinuous microstructure, and then films with GE-in-DE microstructure. And homogeneous films showed the best film properties, followed by films with relatively homogeneous texture, and then films with uneven texture. The weight loss results suggested the potential of GE-DE edible films for application in cherry tomato preservation. This work provided interesting information for the design of film with fabricated microstructure and properties.

Intelligent food tag: A starch-anthocyanin-based pH-sensitive electrospun nanofiber mat for real-time food freshness monitoring.

A starch-based nanofiber mat was prepared for real-time monitoring of food freshness for the first time. UV-vis results showed that roselle anthocyanins (RS) conferred a wide pH sensing range on the nanofiber mat. The prepared nanofiber mats demonstrated good color visibility (total color difference value (ΔE) increased to 56.4 ± 0.7) and a reversible response (within 120 s). Scanning electron microscopy and Fourier transform infrared spectroscopy results suggested that the nanofibers had smooth surfaces without beaded fibers and that RS was well embedded into the nanofibers. The introduction of RS improved the thermal stability of the nanofibers. Color stability tests revealed that the nanofibers exhibited excellent color stability (maximum change ΔE = 1.57 ± 0.03) after 14 days of storage. Pork and shrimp freshness tests verified that the nanofibers could effectively reflect the dynamic freshness of pork and shrimp. Nontoxic, degradable and responsive characteristics make the pH-sensitive nanofiber mat a smart food label with great application potential.

Adsorption properties of corn starch modified by malt amylases and crosslinking agents: A comparison between sodium trimetaphosphate and organic acids.

In order to investigate the effects of different crosslinking agents on physicochemical properties and adsorption properties of porous starch. Native corn starch was hydrolyzed by maltase and crosslinked with different crosslinking agents. Sodium trimetaphosphate crosslinked porous starch (STMP-MPS), malic acid cross-linked porous starch (MA-MPS) and citric acid cross-linked porous starch (CA-MPS) were prepared. After crosslinking, MA-MPS and CA-MPS showed a new CO stretching absorption peak at 1738 cm-1, and the crosslinking degree was much higher than that of STMP-MPS. The surface area of MA-MPS was 36 % higher than that of STMP-MPS. Compared with the average pore size of 12.43 nm of STMP-MPS, CA-MPS (14.02 nm) and MA-MPS (14.79 nm) were increased more significantly. The degradation temperature of MA-MPS and CA-MPS was increased by the introduction of ester bond, which indicates that the organic acid cross-linking strengthens the starch granules and hence more energy is required for disruption. Compared with STMP-MPS, the water absorption of MA-MPS and CA-MPS increased by 64 % and 32 %, respectively. Furthermore, the adsorption capacity of MA-MPS to essential oil was the strongest, about 4 times that of STMP-MPS. Overall, it is feasible to modify porous starch by crosslinking reaction to improve its heat resistance and adsorption properties.

Influence of heat treatment before and/or after high-pressure homogenization on the structure and emulsification properties of soybean protein isolate.

This study investigates the effects of heat treatment before high-pressure homogenization (HHPH) and heat treatment after high-pressure homogenization (HPHH) at different pressures (20, 60, and 100 MPa) on the structural and emulsification properties of soy protein isolate (SPI). The results indicate that HHPH treatment increases the surface hydrophobicity (H0) of the SPI, reduces ß-fold and irregular curls, leading to the formation of soluble aggregates, increased adsorbed protein content, and subsequent improvements in emulsification activity index (EAI) and emulsion stability index (ESI). In contrast, the HPHH treatment promoted the exchange of SH/SS bonds between protein molecules and facilitated the interaction of basic peptides and ß-subunits, leading to larger particle sizes of the soluble aggregates compared to the HHPH-treated samples. However, excessive aggregation in HPHH-treated aggregates leads to decreased H0 and adsorbed protein content, and increased interfacial tension, negatively affecting the emulsification properties. Compared to the HPHH treatment, HHPH treatment at homogenization pressures of 20 to 100 MPa increases EAI and ESI by 5.81-29.6 % and 5.31-25.9 %, respectively. These findings provide a fundamental basis for soybean protein manufacturers to employ appropriate processing procedures aimed at improving emulsification properties.

Microbial modifications with Lycium barbarum L. oligosaccharides decrease hepatic fibrosis and mitochondrial abnormalities in mice.

BACKGROUND: Lycium barbarum L. is a typical Chinese herbal and edible plant and are now consumed globally. Low molecular weight L. barbarum L. oligosaccharides (LBO) exhibit better antioxidant activity and gastrointestinal digestibility in vitro than high molecular weight polysaccharides. However, the LBO on the treatment of liver disease is not studied. PURPOSE: Modification of the gut microbial ecosystem by LBO is a promising treatment for liver fibrosis. STUDY DESIGN AND METHODS: Herein, LBO were prepared and characterized. CCl4-treated mice were orally gavaged with LBO and the effects on hepatic fibrosis and mitochondrial abnormalities were evaluated according to relevant indicators (gut microbiota, faecal metabolites, and physiological and biochemical indices). RESULTS: The results revealed that LBO, a potential prebiotic source, is a pyranose cyclic oligosaccharide possessing α-glycosidic and ß-glycosidic bonds. Moreover, LBO supplementation restored the configuration of the bacterial community, enhanced the proliferation of beneficial species in the gastrointestinal tract (e.g., Bacillus, Tyzzerella, Fournierella and Coriobacteriaceae UCG-002), improved microbial metabolic alterations (i.e., carbohydrate metabolism, vitamin metabolism and entero-hepatic circulation), and increased antioxidants, including doxepin, in mice. Finally, LBO administration reduced serum inflammatory cytokine and hepatic hydroxyproline levels, improved intestinal and hepatic mitochondrial functions, and ameliorated mouse liver fibrosis. CONCLUSION: These findings indicate that LBO can be utilized as a prebiotic and has a remarkable ability to mitigate liver fibrosis.

Maltogenic amylase: Its structure, molecular modification, and effects on starch and starch-based products.

Maltogenic amylase (MAA) (EC3.2.1.133), a member of the glycoside hydrolase family 13 that mainly produces α-maltose, is widely used to extend the shelf life of bread as it softens bread, improves its elasticity, and preserves its flavor without affecting dough processing. Moreover, MAA is used as an improver in flour products. Despite its antiaging properties, the hydrolytic capacity and thermal stability of MAA can't meet the requirements of industrial application. However, genetic engineering techniques used for the molecular modification of MAA can alter its functional properties to meet application-specific requirements. This review briefly introduces the structure and functions of MAA, its application in starch modification, its effects on starch-based products, and its molecular modification to provide better insights for the application of genetically modified MAA in starch modification.

Advances in Starch Nanoparticle for Emulsion Stabilization.

Starch nanoparticles (SNPs) are generally defined as starch grains smaller than 600-1000 nm produced from a series of physical, chemical, or biologically modified starches. Many studies have reported the preparation and modification of SNPs, which are mostly based on the traditional "top-down" strategy. The preparation process generally has problems with process complexity, long reaction periods, low yield, high energy consumption, poor repeatability, etc. A "bottom-up" strategy, such as an anti-solvent method, is proven to be suitable for the preparation of SNPs, and they are synthesized with small particle size, good repeatability, a low requirement on equipment, simple operation, and great development potential. The surface of raw starch contains a large amount of hydroxyl and has a high degree of hydrophilicity, while SNP is a potential emulsifier for food and non-food applications.

Effects of different ratios of mannitol to sorbitol on the functional properties of sweet potato starch films.

Sorbitol as a plasticizer is easily crystallized from starch film, resulting in the reduction in plasticizing effect. To improve the plasticizing performance of sorbitol in starch films, mannitol, an acyclic hexahydroxy sugar alcohol, was used to cooperate with sorbitol. The effects of different ratios of mannitol (M) to sorbitol (S) as a plasticizer on mechanical properties, thermal properties, water resistance and surface roughness of sweet potato starch films were investigated. The results showed that the surface roughness of starch film with M:S (60:40) was the smallest. The number of hydrogen bonds between plasticizer and starch molecule was proportional to the mannitol content starch film. With the decrease of mannitol contents, the tensile strength of starch films gradually decreased except for M:S (60:40). Moreover, the transverse relaxation time value of starch film with M:S (100:0) was the lowest, indicating that it had the lowest degree of freedom of water molecules. Starch film with M:S (60:40) is the most effective in delaying the retrogradation of starch film. This study offered a new theoretical basis that different ratios of mannitol to sorbitol improve different performances of starch films.

Hierarchical structural modification of starch via non-thermal plasma: A state-of-the-art review.

The hierarchical architecture of natural and processed starches with different surface and internal structures determines their final physicochemical properties. However, the oriented control of starch structure presents a significant challenge, and non-thermal plasma (cold plasma, CP) has gradually been used to design and tailor starch macromolecules, though without clear illustration. In this review, the multi-scale structure (i.e., chain-length distribution, crystal structure, lamellar structure, and particle surface) of starch is summarized by CP treatment. The plasma type, mode, medium gas and mechanism are also illustrated, as well as their sustainable food applications, such as in food taste, safety, and packaging. The effects of CP on the chain-length distribution, lamellar structure, amorphous zone, and particle surface/core of starch includes irregularity due to the complex of CP types, action modes, and reactive conditions. CP-induced chain breaks lead to short-chain distributions in starch, but this rule is no longer useful when CP is combined with other physical treatments. The degree but not type of starch crystals is indirectly influenced by CP through attacking the amorphous region. Furthermore, the CP-induced surface corrosion and channel disintegration of starch cause changes in functional properties for starch-related applications.

Self-healing properties of retrograded starch films with enzyme-treated waxy maize starch as healing agent.

Waxy maize starch (WMS) was modified using sequential α-amylase and transglucosidase to create enzyme-treated waxy maize starch (EWMS) with higher branching degree and lower viscosity as an ideal healing agent. Self-healing properties of retrograded starch films with microcapsules containing WMS (WMC) and EWMS (EWMC) were investigated. The results indicated that EWMS-16 had the maximum branching degree of 21.88 % after transglucosidase treatment time of 16 h, and A chain of 12.89 %, B1 chain of 60.76 %, B2 chain of 18.82 % and B3 chain of 7.52 %. The particle sizes of EWMC ranged from 2.754 to 5.754 µm. The embedding rate of EWMC was 50.08 %. Compared to retrograded starch films with WMC, water vapor transmission coefficients of retrograded starch films with EWMC were lower, while tensile strength and elongation at break values of retrograded starch films were almost similar. Retrograded starch films with EWMC had higher healing efficiency of 58.33 % as compared to that Retrograded starch films retrograded starch films with WMC was 44.65 %.

Effects of primary, secondary and tertiary structures on functional properties of thermoplastic starch biopolymer blend films.

To better understand the correlation between structure and properties in thermoplastic starch biopolymer blend films, the effects of amylose content, chain length distribution of amylopectin and molecular orientation of thermoplastic sweet potato starch (TSPS) and thermoplastic pea starch (TPES) on microstructure and functional properties of thermoplastic starch biopolymer blend films were studied. After thermoplastic extrusion, the amylose contents of TSPS and TPES decreased by 16.10 % and 13.13 %, respectively. The proportion of the chains with the degree of polymerization between 9 and 24 of amylopectin in TSPS and TPES increased from 67.61 % to 69.50 %, and from 69.51 % to 71.06 %, respectively. As a result, the degree of crystallinity and molecular orientation of TSPS and TPES films increased as compared to sweet potato starch and pea starch films. The thermoplastic starch biopolymer blend films possessed a more homogeneous and compacter network. The tensile strength and water resistance of thermoplastic starch biopolymer blend films increased significantly, whereas thickness and elongation at break of thermoplastic starch biopolymer blend films decreased significantly.

Organic solvent-free starch-based green electrospun nanofiber mats for curcumin encapsulation and delivery.

Developing green and efficient methods for the delivery of active food substances is a sustained demand for food scientists and industries. In this work, for the first time, we prepared a curcumin (CUR)-loaded starch-based fast-dissolving nanofiber by electrospinning technology. This green nanofiber was obtained by incorporating CUR with octenyl succinic anhydride starch (OSA) and pullulan (PUL) matrix using pure water as the solvent. To overcome the poor water-solubility and bioavailability of CUR, hydroxypropyl-beta-cyclodextrin (HPßCD) was used to form inclusion complexes. Phase solubility test results showed that by introducing HPßCD, the water-solubility of CUR was obviously improved. The prepared electrospun nanofibers were systematically characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD), proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), encapsulation efficiency testing, solubility testing and antioxidant activity testing. The results demonstrated that CUR was well encapsulated into HPßCD and OSA/PUL/CUR-HPßCD electrospun nanofibers with fine morphology and fast-dissolving character were successfully prepared. It is worth noting that the whole process and raw materials were green, suggesting that the prepared fast-dissolving nanofiber has great application potential in the food and pharmaceutical fields.

Effects of different rapid cooling temperatures and annealing on functional properties of starch straws after thermoplastic extrusion.

To improve the performance of starch straws in rapidly cooling and annealing procedure of thermoplastic extrusion, control straw was prepared through slowly cooling at 25 °C, and starch straw was prepared through regulating different rapid cooling temperatures including 20 °C, 5 °C, -10 °C and -20 °C. The results indicated that control straw exhibited a homogeneous state, while starch straws treated by rapid cooling displayed like a wash-board structure. Compared to control straw, the ratio of the absorption peak intensity of 1047 and 1022 cm-1 increased from 1.050 to 1.455 as cooling temperatures decreased from 25 °C to -20 °C, indicating short-range order of the double helix structure significantly enhanced. The relative crystallinities of starch straws increased from 12.01 % to 16.58 %. The maximum bending force value (60.92 N) of starch straws cooled at -20 °C was significantly higher than that (46.14 N) of control straw. Conversely, the modulus of elasticity in bending values (4.21-16.43 N/cm) of rapid cooling-treated straws were significantly lower than that (48.42 N/cm) of control straw. Water absorption of rapid cooling-treated straws were lower than that of control straw, indicating the hydrophobicity property of starch straws significantly improved.

The relationship between molecular structure and film-forming properties of thermoplastic starches from different botanical sources.

To illustrate the correlations between molecular structures and the film-forming properties of thermoplastic starch from various botanical sources, starches from cereal, tuber and legume were modified by thermoplastic extrusion and the corresponding thermoplastic starch films were prepared including thermoplastic corn starch (TCS), thermoplastic rice starch (TRS), thermoplastic sweet potato starch (TSPS), thermoplastic cassava starch (TCAS) and thermoplastic pea starch (TPES) films. TPES film displayed a higher tensile strength (6.28 MPa) and stronger water resistance, such as lower water solubility (15.70 %), water absorption (42.35 %), and water vapor permeability (0.285 g·mm·h-1·m-2·kPa-1) due to higher contents of amylose and B1 chains. TCAS showed a smoother and more amorphous film due to higher amylopectin content, resulting higher elongation at break and larger opacity. TCS film was the most transparent due to a compacter network and more ordered crystallinity structure, which was suit for the packaging of fresh vegetables and aquatic products, whereas TCAS film was the opaquest, which protected package foods from light such as meat products, etc. The outcome would provide an innovative theory to regulate accurately the functional properties of thermoplastic starch films for different food needs.

Improving the sensitivity of lateral flow immunoassay for Salmonella typhimurium detection via flow-rate regulation.

Application of the traditional immunochromatographic assay (ICGA) has been limited by its poor sensitivity. The objective of this study was to increase the sensitivity of the traditional ICGA. A dual-mode ICGA (D-M ICGA) was developed by combining a nanozyme-assisted signal-amplification strategy with a magnetic-nanoparticle-based flow-speed-control strategy. Salmonella typhimurium can be detected simultaneously based on color and magnetic signals in the detection area of the D-M ICGA strip. The calculated limits of detection of 50 cfu·mL-1 and 75 cfu·mL-1 in the color and magnetic modes, respectively, were approximately 1000 times lower than those of the traditional ICGA. The selectivity and practical applicability of the D-M ICGA were also confirmed in this study. The results prove that the D-M ICGA is an assay that could be used for Salmonella typhimurium detection and can be easily adapted to detect other pathogenic bacteria.

Function emulsion gels prepared with carrageenan and zein/carboxymethyl dextrin stabilized emulsion as a new fat replacer in sausages.

Emulsion gels prepared with carrageenan and emulsion stabilized by zein/carboxymethyl dextrin were served as fat substitute in sausages. Color, pH, texture, rheology, microstructure, cooking loss and antioxidant activity of sausages were assessed. The replacement of emulsion gels increased L* and decreased a* of sausages. The incorporation of curcumin increased b* of sausages. The pH of sausages had no obviously change when the emulsion gels and curcumin were used as fat substitute. The hardness and viscoelasticity of sausages improved with the addition of emulsion gels. The SEM suggested that network structure was enhanced with the increase of emulsion gels. After adding emulsion gels and curcumin, the cooking loss of sausages was significantly decreased and antioxidant activity was significantly increased. This study indicated that emulsion gels, which was fabricated by carrageenan and emulsion stabilized by zein/carboxymethyl dextrin, could be an excellent substitute to replace fat in sausages.

Ultrasonication effects on physicochemical properties of starch-lipid complex.

The starch-lipid complex between the pea starch (PSt) and glycerol monolaurate (GM) was prepared using ultrasound with different amplitudes, durations and application sequences. Fourier-transform infrared and nuclear magnetic resonance spectra showed the formation of amylose-lipid complex between PSt and GM in the ultrasonic field. Stronger diffraction intensities were observed in samples treated by ultrasonication, whereas the thermogravimetric analysis indicated that the thermal stability of starch was improved by the formation of the V-type inclusion complexes. An ultrasound pre-treatment prior to the addition of a guest molecule (UC) was more favorable to induce the formation of an amylose-lipid complexes than ultrasound treatment after PSt was incorporated with GM (CU). The UC-treated samples showed stronger diffraction intensities, higher melting enthalpy values and enzyme-resistant than that of CU-treated PSt-GM complexes.

Effects of connection mode on acid hydrolysis of corn starch during induced electric field treatment.

This study aimed to explore the effect of induced electric field (IEF) treatment on acid hydrolysis of corn starch by altering the connection modes of sample coils of a 4-reactor IEF system. Results suggested that IEF treatment could enhance the hydrolysis of corn starch and series connection (1. RRRR, η=16ESi2Pin4ZSi+Zload) exhibited higher energy efficiency than parallel (9. (RRRR), η=4ESi2PinZSi+4Zload), thus contributing to more extensive hydrolysis. Although no new functional group was formed, the starch granules were partially cracked into pieces and the crystallinity was slightly increased after IEF-assisted hydrolysis. Differential scanning calorimetry results indicated that IEF-assisted hydrolysis increased the gelatinization temperatures but decreased the enthalpy of starch, with a greatest variation was observed by series connection. Rapid visco-analysis showed that IEF-assisted hydrolysis greatly decreased the pasting viscosity of corn starch and also series connection showed the strongest reduction. The obtained results could provide a theoretical guide for the applications of IEF technology in biomaterial processing.

Pickering emulsions stabilized by ß-cyclodextrin and cinnamaldehyde essential oil/ß-cyclodextrin composite: A comparison study.

Here, a cinnamaldehyde essential oil (CEO)/ß-Cyclodextrin (ß-CD) composite with a high embedding rate (91.74 ± 0.82%) was prepared. Its structure was characterized by Fourier transform infrared spectrometer (FT-IR) and X-ray diffractometer (XRD). Pickering emulsions prepared by ß-CD and CEO/ß-CD at different concentrations (1-5%) were comparatively investigated. The CEO/ß-CD emulsions had better storage stability. Rheological results confirmed the emulsions were all gel-like elastic emulsions and had shear thinning phenomenon. Fluorescence microscopy and scanning electron microscopy (SEM) results confirmed that the most of excessive ß-CD was adsorbed on the surface of emulsion droplets as crystals, formed thick protective shell in ß-CD emulsions, while the most of excessive composites were distributed in the aqueous phase forming a stable network structure in CEO/ß-CD emulsions. It caused these two emulsions had different rheological properties, and different changing trends in droplet size.