Qinghuang Wang

Homogeneous isolation of nanocellulose from sugarcane bagasse by high pressure homogenization

Nanocellulose from sugarcane bagasse was isolated by high pressure homogenization in a homogeneous media. Pretreatment with an ionic liquid (1-butyl-3-methylimidazolium chloride ([Bmim]Cl)) was initially involved to dissolve the bagasse cellulose. Subsequently, the homogeneous solution was passed through a high pressure homogenizer without any clogging. The nanocellulose was obtained at 80 MPa for 30 cycles with recovery of 90% under the optimum refining condition. Nanocellulose had been characterized by Fourier transformed infrared spectra, X-ray diffraction, thermogravimetric analysis, rheological measurements and transmission electron microscopy. The results showed that nanocellulose was 10-20 nm in diameter, and presented lower thermal stability and crystallinity than the original cellulose. The developed nanocellulose would be a very versatile renewable material.

Development and evaluation of novel flavour microcapsules containing vanilla oil using complex coacervation approach.

A novel flavour microcapsule containing vanilla oil (VO) was developed using complex coacervation approach, aimed to control release of VO and enhance its thermostability for spice application in food industry. Viscosity of chitosan (CS) and VO/CS ratio were optimised for fabrication of microcapsules. The flavour microcapsules were evaluated by scanning electron micrograph (SEM), laser confocal microscopy (LSCM), particle size analyser, infrared spectrometer (FT-IR), thermal analysis and controlled-release analysis. The microcapsules were in spherical with good dispersibility when moderate viscosity CS was used. 94.2% of encapsulation efficiency was achieved in VO/CS ratio of 2:1. The FT-IR study proved chemical cross-linking reaction occurred between genipin and chitosan, but a physical interaction between CS and VO. A core-shell structure of microcapsule was confirmed by LSCM, which was beneficial to improve the thermostability of VO in microcapsule. Moreover, VO could be remained about 60% in the microcapsules after release for 30 days, which demonstrated the flavour microcapsules had good potential to serve as a high quality food spice with long residual action and high thermostability.

Reinforcement of natural rubber with core-shell structure silica-poly(methyl methacrylate) nanoparticles

A highly performing natural rubber/silica (NR/SiO2) nanocomposite with a SiO2 loading of 2wt% was prepared by combining similar dissolve mutually theory with latex compounding techniques. Before polymerization, double bonds were introduced onto the surface of the SiO2 particles with the silane-coupling agent. The core-shell structure silica-poly(methyl methacrylate), SiO2- PMMA, nanoparticles were formed by grafting polymerization of MMA on the surface of the modified SiO2 particles via in situ emulsion, and then NR/SiO2 nanocomposite was prepared by blending SiO2-PMMA and PMMA-modified NR (NR-PMMA). The Fourier transforminfrared spectroscopy results show that PMMA has been successfully introduced onto the surface of SiO2, which can be well dispersed in NR matrix and present good interfacial adhesion with NR phase. Compared with those of pure NR, the thermal resistance and tensile properties of NR/SiO2 nanocomposite are significantly improved.

The effect of cryogenic grinding and hammer milling on the flavour quality of ground pepper (Piper nigrum L.)

In this study, we compared the effects of cryogenic grinding and hammer milling on the flavour attributes of black, white, and green pepper. The flavour attributes were analysed using headspace solid-phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC/MS), sensory evaluation and electronic nose (e-nose) analysis. Cryogenic grinding resulted in minimal damage to the colour, flavour, and sensory attributes of the spices. Cryogenic grinding was also better than hammer milling at preserving the main potent aroma constituents, but the concentrations of the main aroma constituents were dramatically reduced after storing the samples at 4 °C for 6 months. Pattern matching performed by the e-nose further supported our sensory and instrumental findings. Overall, cryogenic grinding was superior to hammer milling for preserving the sensory properties and flavour attributes of pepper without significantly affecting its quality. However, we found that the flavour quality of ground pepper was reduced during storage.

Study on nanocellulose by high pressure homogenization in homogeneous isolation

Nanocellulose from cotton cellulose was prepared by high pressure homogenization (HPH) in ionic liquids (1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The nanocellulose possessed narrow particle size distribution, with diameter range of 10–20 nm. Weight average molecular weight (Mw) of nanocellulose treated by HPH was lower (173.8 kDa) than the one ILs treated cellulose (344.6 kDa). X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and Solid-state CP/MAS 13C NMR measurements were employed to study the mechanism of structural changes, which suggested that network structure between cellulose chains were destructed by the shearing forces of HPH in combination with ionic liquids. The intermolecular and intra-molecular hydrogen bonds of cellulose were further destroyed, leading to the long cellulose molecular chains being collapsed into short chains. Therefore, the nanocellulose could provide desired properties, such as lower thermal stability and strong water holding capacity. Results indicated that it had great potential in the applications for packaging, medicines, cosmetics and tissue engineering.

Homogeneous isolation of nanocelluloses by controlling the shearing force and pressure in microenvironment

Nanocelluloses were prepared from sugarcane bagasse celluloses by dynamic high pressure microfluidization (DHPM), aiming at achieving a homogeneous isolation through the controlling of shearing force and pressure within a microenvironment. In the DHPM process, the homogeneous cellulose solution passed through chambers at a higher pressure in fewer cycles, compared with the high pressure homogenization (HPH) process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) demonstrated that entangled network structures of celluloses were well dispersed in the microenvironment, which provided proper shearing forces and pressure to fracture the hydrogen bonds. Gel permeation chromatography (GPC), CP/MAS (13)C NMR and Fourier transform infrared spectroscopy (FT-IR) measurements suggested that intra-molecular hydrogen bonds were maintained. These nanocelluloses of smaller particle size, good dispersion and lower thermal stability will have great potential to be applied in electronics devices, electrochemistry, medicine, and package and printing industry.

Analysis of the blackening of green pepper (Piper nigrum Linnaeus) berries

This paper investigates polyphenol oxidase (PPO) activity, reduced weight percentage after sun drying, and the changes in colour and appearance of green pepper (Piper nigrum Linnaeus) berries after blanching and sun drying. The results show that the degree of reduced weight percentage and browning in green pepper berries after blanching for 10 min is greater at 100°C than at 90 and 80°C. Moreover, the samples blanched at 100°C for 10 min had the fastest water loss, but the lowest PPO activity. Thus, the PPO enzymatic oxidation of polyphenols might not be the only reason for the browning of green pepper berries. This result is significantly different from that of Variyar, Pendharkar, Banerjeea, and Bandyopadhyay (1988) and therefore deserves further study.

Synthesis and Characterization of Superparamagnetic Fe3O4 Nanoparticles Modified with Oleic Acid

The effect of oleic acid on the superparamagnetic Fe3O4 nanoparticles has been investigated in this study. The addition of oleic acid could improve the particle size distribution by the formed protective layer on the surface of Fe3O4 nanoparticles. All of Fe3O4 coated with oleic acid displayed superparamagnetic characterizations, and the interaction between two competing mechanisms, agglomeration and chelation, was discussed to explain the function of oleic acid. The optimal addition of oleic acid was fixed to be 4 wt%, which obtained the highest magnetization saturation value (Ms) of 82.066 emu/g.

Microencapsulation of coupled folate and chitosan nanoparticles for targeted delivery of combination drugs to colon

Abstract Folate−chitosan nanoparticles, co-loaded with 5-fluourouacil (5-FU) and leucovorin (LV) and prepared by ionic gelation technology were physically microencapsulated by enteric polymer using a solvent evaporation method. Average particle size of the microencapsulated particles was in the range of 15 to 35 µm. High drug encapsulation efficiency was obtained for both 5-FU and LV in the microencapsulated particles. Both drugs were in amorphous state in the microencapsulated particles. By enteric coating, excellent pH-dependent release profile was achieved and no drug release was observed in simulated gastric and intestinal fluids. However, when the pH value reached the soluble threshold of Eudragit S-100, a constant and slow drug release was observed. The results indicated that these microencapsulated particles are a promising vehicle for selectively targeting drugs to colon in the chemotherapy of colon cancer.

Development of drug-loaded chitosan–vanillin nanoparticles and its cytotoxicity against HT-29 cells

Abstract Chitosan as a natural polysaccharide derived from chitin of arthropods like shrimp and crab, attracts much interest due to its inherent properties, especially for application in biomedical materials. Presently, biodegradable and biocompatible chitosan nanoparticles are attractive for drug delivery. However, some physicochemical characteristics of chitosan nanoparticles still need to be further improved in practice. In this work, chitosan nanoparticles were produced by crosslinking chitosan with 3-methoxy-4-hydroxybenzaldehyde (vanillin) through a Schiff reaction. Chitosan nanoparticles were 200–250 nm in diameter with smooth surface and were negatively charged with a zeta potential of − 17.4 mV in neutral solution. Efficient drug loading and drug encapsulation were achieved using 5-fluorouracil as a model of hydrophilic drug. Drug release from the nanoparticles was constant and controllable. The in vitro cytotoxicity against HT-29 cells and cellular uptake of the chitosan nanoparticles were evaluated by methyl thiazolyl tetrazolium method, confocal laser scanning microscope and flow cytometer, respectively. The results indicate that the chitosan nanoparticles crosslinked with vanillin are a promising vehicle for the delivery of anticancer drugs.