Modulation of the properties of starch gels by a one-step extrusion modification method based on Ca2+-citric acid synergistic crosslinking.

Citric acid (CA) is a green and safe food-grade crosslinking agent for starch, but its high crosslinking temperature limits its application. In this study, a "one-step" extrusion modification method based on Ca2+-esterification synergistic crosslinking was proposed for the preparation of high gel performance crosslinked starch at low temperatures (90 °C). The linear and nonlinear rheological properties of crosslinked starch were comprehensively characterized, and the enhancement effect of synergistic crosslinking reactions on starch gel properties was quantitatively studied. The results show that the elastic modulus of the synergistically crosslinked starch (SC-0.5Ca2+, G' = 3116 ± 36) was significantly increased by 879 % compared to the elastic modulus of starch without synergistically crosslinked modification (SC, G' = 318 ± 9). The elastic modulus of starch gels can be adjusted by changing the ion concentration. Nonlinear rheological Lissajous curve analysis results show that the synergistic crosslinked gel system has a stronger anti-deformation ability. In addition, the honeycomb porous structure and smaller pore size distribution of the synergistic crosslinked gels were characterized using scanning SEM. The XPS, FTIR and XRD results suggest that the synergistic crosslinking enhancement effect may involve various molecular forces such as electrostatic attraction, hydrogen bonding and ester bonding.

Enhancement of Starch Gel Properties Using Ionic Synergistic Multiple Crosslinking Extrusion Modification.

Crosslinking is a promising method to modulate the gel properties of food-grade starch gels. Still, the poor crosslinking effect of a single type of crosslinker limits the application of this method in starch gel modification. In this study, an Ca2+ synergistic multiple crosslinking modification method was proposed to prepare crosslinked starches with good gel properties and setting. The rheological properties of the samples were tested. The modified sample (SC-Ca-N3, G' = 1347 ± 27) showed a 79% improvement compared to the starch without synergistic crosslinking modification (SC-N, G' = 752 ± 6). The elastic modulus of starch gels can be adjusted by changing the degree of the crosslinking reaction. The results of nonlinear rheological Lissajous curve analysis showed that the synergistically crosslinked gel system strongly resisted deformation. In addition, the microstructure of the modified samples was characterized using scanning electron microscopy. The XPS, FTIR, and XRD results indicated that multiple molecular forces participate in the synergistic crosslinking reaction.

Antimicrobial cellulose paper tuned with chitosan fibers for high-flux oil/water separation.

Separating films with both high efficiency and large flux are desperately needed to meet the rising demand for the treatment of oily wastewater, while traditional oil/water separation papers with high separation efficiency usually suffered from low flux due to the unsuitable size of filtration pores. Herein, we report a bio-based porous, superhydrophobic, and antimicrobial hybrid cellulose paper with tunable porous structures for high flux oil/water separation. The size of pores in the hybrid paper can be tuned by both physical supports provided by the chitosan fibers and the chemical shielding supplied by the hydrophobic modification. The hybrid paper with increased porosity (20.73 µm; 35.15 %) and excellent antibacterial properties can efficiently separate a wide range of oil/water mixtures, solely by gravity, with outstanding flux (maximum of 23,692.69 L m-2 h-1), tiny oil interception, and high efficiency of over 99 %. This work provides new sights in the development of durable and low-cost functional papers for rapid and efficient oil/water separation.

Twin-Screw Extrusion of Oat: Evolutions of Rheological Behavior, Thermal Properties and Structures of Extruded Oat in Different Extrusion Zones.

Further investigation of material properties during the extrusion process is essential to achieve precise control of the quality of the extrudate. Whole oat flour was used to produce low moisture puffed samples by a twin-screw extruder. X-ray diffraction (XRD), Scanning electron microscopy (SEM), infrared spectroscopy (FTIR), thermal analysis, and rheological experiments were used to deeply characterize changes in the structure and cross-linking of oats in different extrusion zones. Results indicated that the melting region was the main region that changed oat starch, including the major transformation of oat starch crystal morphology and the significant decrease of enthalpy representing the starch pasting peak in the differential scanning calorimeter (DSC) pattern (p < 0.05). Moreover, the unstable structure of the protein increased in the barrel and then decreased significantly (p < 0.05) after being extruded through the die head. The viscosity of oats increased in the cooking zone but decreased after the melting zone. A transformation occurred from elastic-dominant behavior to viscoelastic-dominant behavior for oats in the melting zone and after being extruded. This study provides further theoretical support for the research of the change of materials during extrusion and the development of oat-based food.

A green 3-step combined modification for the preparation of biomass sorbent from waste chestnut thorns shell to efficient removal of methylene blue.

Although several green methods for the preparation of biomass adsorbents have been proposed, the low adsorption performance of the biomass adsorbents prepared by these methods has limited the development of this technological route. This is the first work that uses an ultrasound-assisted binary solvent system and low temperature ice crystal fixation to achieve high adsorption performance of a biomass sorbent. Chestnut thorns shell (CTS) sorbent with high adsorption performance on MB was successfully prepared with an adsorption performance of 305.81 mg/g, which is on par with most high temperature carbonized adsorbents. Further reaction kinetics, TEM, XPS and FTIR studies showed that the MB adsorption of CTS was through electrostatic attraction, hydrogen bonding, ion-dipole interaction and π-π interaction. After five cycles, the adsorption capacity of the adsorbent remained at a high level. This work provided an effective strategy for safer and greener preparation of high adsorption performance adsorbents from agroforestry waste.

Effect of Combined Infrared and Hot Air Drying Strategies on the Quality of Chrysanthemum (Chrysanthemum morifolium Ramat.) Cakes: Drying Behavior, Aroma Profiles and Phenolic Compounds.

Chrysanthemum (Chrysanthemum morifolium Ramat.) is a seasonal plant with high medicinal and aesthetic value, and drying is an effective practice to enhance its storability after harvesting. The effects of hot air drying (HAD), combined infrared and hot air drying (IR-HAD), and sequential IR-HAD and HAD (IR-HAD + HAD) on the drying behavior, color, shrinkage, aroma profiles, phenolic compounds, and microstructure of chrysanthemum cakes were studied. Results showed that the increasing temperature resulted in a decrease in drying time and an increase in drying rate and moisture diffusivity. The Logarithmic and Page models exhibited superior fit in describing the dehydration process. Among the three drying strategies, IR-HAD was more effective in reducing energy consumption, improving shrinkage, water holding capacity, water binding capacity and cellular microstructure, while IR-HAD + HAD showed better inhibitory effect on color deterioration. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis revealed that different drying strategies dramatically influenced the aroma profiles in samples, and IR-HAD obtained the highest concentration of volatiles. The results of ultra-performance liquid chromatography (UPLC) indicated that the introduction of infrared radiation contributed to increasing the contents of chlorogenic acid, luteolin, total phenolic and flavonoid. These suggested that IR-HAD was a promising technique for drying medicinal chrysanthemum.

Amphiphilic dendritic nanomicelle-mediated co-delivery of 5-fluorouracil and doxorubicin for enhanced therapeutic efficacy.

Combination cancer therapy has attracted considerable attention due to its enhanced antitumor efficacy and reduced toxicity granted by synergistic effects over monotherapy. The application of nanotechnology is expected to achieve coencapsulation of multiple anticancer agents with enhanced therapeutic efficacy. Herein, a unique nanomicelle based on amphiphilic dendrimer (AmD) consisting of a hydrophilic polyamidoamine dendritic shell and a hydrophobic polylactide core is developed for effectively loading and shuttling 5-fluorouracil (5-Fu) and doxorubicin (Dox). The yielded drug-encapsulated dendritic nanomicelle (5-Fu/Dox-DNM) has a modest average size of 68.6 ± 3.3 nm and shows pH-sensitive drug release manner. The parallel activity of 5-Fu and Dox show synergistic anticancer efficacy. The IC50 value of 5-Fu/Dox-DNM toward human breast cancer (MDA-MB-231) cells was 0.25 µg/mL, presenting an 11.2-fold and 6.1-fold increase in cytotoxicity compared to Dox-DNM and 5-Fu-DNM, respectively. Furthermore, 5-Fu/Dox-DNM significantly inhibits the progression of tumor growth in the MDA-MB-231 xenograft tumor mice model. In conclusion, we have demonstrated that our AmD-based combination therapeutic system has promising potential to open an avenue for coencapsulation of multiple chemotherapeutic agents to promote superior anticancer effect.