Zhengzong Wu

In situ synthesis of new magnetite chitosan/carrageenan nanocomposites by electrostatic interactions for protein delivery applications

We present a simple method to develop magnetite chitosan/carrageenan nanocomposites by in situ synthesis under mild conditions, and then their potential for controlled release of macromolecules was also evaluated. The structural, morphological and magnetic properties of the as-prepared materials were studied by vibrating sample magnetometer, X-ray diffractometer, Fourier transform infrared spectroscopy, thermogravimetric analyzer and transmission electron microscopy. With the varying mass ratio (chitosan to Fe3O4-carrageenan nanocomposite), the developed nanocarriers presented sizes within 73-355nm and zeta potentials of -42-32mV. Using bovine serum albumin as model protein, the adsorption and release behaviors were investigated. Nanocarriers evidenced excellent loading capacity of 181mgg(-1) at protein concentration of 0.2mgmL(-1), and demonstrated capacity to provide a sustained release up to 85% of adsorbed protein in 30min in intestinal medium rather than acidic medium. These results suggest that the developed magnetite chitosan/carrageenan nanocomposites are promising in the application of magnetically targeted delivery of therapeutic macromolecules.

Impact of high-shear extrusion combined with enzymatic hydrolysis on rice properties and Chinese rice wine fermentation.

To better understand how high-shear extrusion combined with enzymatic hydrolysis affects the rice properties and subsequent fermentation, a twin screw extruder incorporated with rice treatment with thermostable α-amylase was used for simultaneous saccharification and fermentation (SSF) of Chinese rice wine. Seven pretreatment methods for rice were compared, and their impacts on rice properties and quality indices of final wine were studied. Enzymatic extruded rice had higher water solubility index (WSI), extent of gelatinization (GE), but lower water absorption index (WAI) and viscosity than those of other treated rice due to a strong synergy of shear action and enzymatic hydrolysis on the degradation and gelatinization of starch. The modification of enzymatic autoclaved rice was smaller than that of enzymatic extruded rice mainly for the lack of mechanical shearing force. Although extrusion with smaller particle size tended to have higher susceptibility to enzyme, the effect was not dramatic. This implied that manipulating particle size had limited effect on the modification of rice properties. Correlation analysis showed that the ethanol yield (EY), fermentation efficiency (FE), amino acid (AA), and soluble solid content (SSC) of finished rice wine increased as rice properties improved by enzymatic extrusion. Overall, simultaneous high-shear extrusion and enzymatic hydrolysis can be an attractive alternative to obtain modified rice with desirable properties for manufacturing Chinese rice wine or other fermentation products.

Comparison between ATR-IR, Raman, concatenated ATR-IR and Raman spectroscopy for the determination of total antioxidant capacity and total phenolic content of Chinese rice wine.

The application of attenuated total reflectance infrared spectroscopy (ATR-IR), Raman spectroscopy (RS) and combination of ATR-IR and RS for measurements of total antioxidant capacity (TAC) and total phenolic content (TPC) of Chinese rice wine (CRW) were investigated in this study. Synergy interval partial least-squares (SiPLS), support vector machine (SVM) and principal component analysis (PCA) were applied to process the merged data from two individual instruments. It was observed that the performances of models based on the RS spectra were better than those based on the ATR-IR spectra. In addition, SVM models based on the efficient information extracted from ATR-IR and RS spectra were superior to PLS models based on the same information and PLS models based on ATR-IR or RS spectra. The overall results demonstrated that integrating ATR-IR and RS was possible and could improve the prediction accuracy of TAC and TPC in CRWs.

Effect of chitosan molecular weight on the formation of chitosan–pullulanase soluble complexes and their application in the immobilization of pullulanase onto Fe3O4–κ-carrageenan nanoparticles

The interactions between pullulanase and chitosans of different molecular weights (Mw) were comprehensively studied, and their applications in pullulanase immobilization onto Fe3O4-κ-carrageenan nanoparticles upon chitosan-pullulanase complexation were also evaluated. Chitosan (CS) complexation with pullulanase was found to be dependent on pH and chitosan Mw. The critical pH of structure-forming events during complexation shifted significantly (p<0.05) to a lower pH with a low Mw chitosan (50kDa) compared to other chitosan types. Binding constants for the chitosan-pullulanase interaction increased in the following order: CS-500<CS-400<CS-50<CS-200. The binding induced alterations in the protein secondary structure, which may affect the enzymatic properties of immobilized pullulanase. Pullulanase immobilized upon CS-50 complexation exhibited the most desirable enzymatic properties. These results indicated that the complexation behavior was mainly dependent on chitosan Mw. This study presents a technique for the production of immobilized pullulanase upon complexation that exhibits potential for applications in continuous syrup production.

New Method for the Immobilization of Pullulanase onto Hybrid Magnetic (Fe3O4–κ-Carrageenan) Nanoparticles by Electrostatic Coupling with Pullulanase/Chitosan Complex

We present a simple method to immobilize pullulanase onto hybrid magnetic (Fe3O4-κ-carrageenan) nanoparticles, involving the in situ synthesis of magnetic carrageenan nanoparticles and the formation of pullulanase/chitosan complex. The complex behavior of pullulanase with chitosan as a function of pH and protein-polysaccharide ratio was studied by turbidimetric titration. Then, the as-prepared immobilized enzymes were characterized by vibrating-sample magnetometer, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometer, and thermogravimetric analysis. It was found that the activity retention of immobilized pullulanase and amount of enzyme loaded reached 95.5% and 96.3 mg/g, respectively, under optimal conditions. The immobilized enzyme exhibited great operational stability (retaining approximately 61% residual activity after ten consecutive reuses), demonstrating that enzyme leakage during the catalysis reaction was efficiently reduced. Furthermore, the activity of immobilized pullulanase was significantly (p < 0.01) higher than that of free pullulanase in a low pH range (pH < 3.0) and temperature over 60 °C, and the immobilized enzymes retained 45% of their initial activity after 5 h at 60 °C, compared to 21% for the free enzyme. These results indicated that immobilized pullulanase was efficient in terms of catalytic activity and can be applied to continuous starch processing applications in the food industry.

Characterization of Volatile Flavor Compounds in Chinese Rice Wine Fermented from Enzymatic Extruded Rice

UNLABELLED Enzymatic extrusion, instead of traditional steam cooking, to treat rice is an efficient and alternative pretreatment for Chinese rice wine fermentation. In order to determine the formation of volatiles in enzymatic extrusion-processed rice wine (EE), and to confirm its characteristic flavor compounds, headspace solid-phase micro-extraction followed by GC-MS was used. A total of 66 volatile compounds were identified in EE. During fermentation, most volatiles generated from enzymatic extruded rice had the similar trends with those from steam-cooked rice, but the differences in the concentration of volatiles indicated a changed balance of flavors release caused by enzymatic extrusion. Besides, the concentrations and sorts of volatiles in EEs fermented from different rice particle sizes, were not dramatically different. By principal component analysis, EE could be distinctly separated from other traditional Chinese rice wines according to its characteristic volatiles, namely, 2-heptanol, 1-octen-3-ol, ethyl 4-hydroxybenzoate, methylpentyl 2-propenoate, γ-hexalactone, and 4-vinylguaiacol. PRACTICAL APPLICATION Enzymatic extrusion liquefaction has been a popular thermal treatment for cereals, and gradually being applied in fermentation and liquor-making industry all over the world. The characterization of volatile flavor compounds in Chinese rice wine processed by enzymatic extrusion liquefaction pretreatment, might be made use not only for a better understanding of this new-type rice wine, but for the further utilization of enzymatic extrusion in other wine or alcohol production as well.

Application of FT-NIR spectroscopy and FT-IR spectroscopy to Chinese rice wine for rapid determination of fermentation process parameters

Effective fermentation monitoring is a growing need during the production of wine due to the rapid pace of change in the industry. Total reducing sugar, pH and amino acid nitrogen (AAN) are the three most important process variables indicating the status of the Chinese rice wine (CRW) fermentation process. In this study, the potential of near-infrared (NIR) spectroscopy and mid-infrared (MIR) spectroscopy as rapid tools to monitor the evolutions of these three chemical parameters involved in the CRW fermentation process was investigated and compared. The results demonstrated that compared with the partial least-squares (PLS) model based on the full spectrum, the model based on the spectra intervals selected by the synergy interval partial least-squares (SiPLS) algorithm had higher prediction accuracy. In addition, nonlinear models outperformed linear models in predicting fermentation parameters. After systemic comparison and discussion, it was found that for either models developed based on NIR spectra or models developed based on MIR spectra, SiPLS-support vector machine (SiSVM) models obtained the best result with the highest prediction precision. The overall results indicated that it was feasible to monitor the fermentation process of Chinese rice wine using NIR and MIR spectroscopy.

Rapid Measurement of Antioxidant Activity and γ-Aminobutyric Acid Content of Chinese Rice Wine by Fourier-Transform Near Infrared Spectroscopy

In this study, Fourier-transform near infrared (FT-NIR) spectroscopy in combination with chemometrics was utilized to determine the antioxidant capacity and γ-aminobutyric acid (GABA) content of Chinese rice wine (CRW). Interval partial least-squares (iPLS) and extreme learning machine (ELM) were used to improve the performances of partial least-squares (PLS) models. In total, four different calibration models, namely PLS, iPLS, ELM, and ELM models based on the subintervals selected by iPLS (iELM), were developed in this study. It was observed that the performances of models based on the efficient spectra intervals selected by iPLS were much better than those based on the full spectrum. In addition, nonlinear models were superior to linear models. After systemically comparison and discussion, it was found that for all of the four parameters determined, iELM model achieved the best result with excellent prediction precision. The coefficient of determination for the prediction set (R2 (pre)), and the residual predictive deviation for the prediction set were 0.932 and 4.07 for 1,1-diphenyl-2-picrylhydrazyl assay, 0.970 and 6.21 for 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt assay, 0.974 and 6.29 for total reducing antioxidant power assay and 0.952 and 4.75 for GABA, respectively. The overall results demonstrated that FT-NIR combined with efficient variable selection algorithm and nonlinear regression tool could be used as a rapid alternative method for the prediction of the antioxidant capacity and GABA content of Chinese rice wine.

Effect of enzymatic (thermostable α-amylase) treatment on the physicochemical and antioxidant properties of extruded rice incorporated with soybean flour.

In order to determine the effect of enzymatic extrusion on the physicochemical and antioxidant properties of rice/soybean mixture, different mass ratios (100/0, 95/5, 85/15, 70/30, 50/50 and 25/75%, w/w) were treated with thermostable α-amylase. The reduced special mechanical energy and the enhanced product temperature were closely and regularly linked with the increase of soybean content. The bulk density and water solubility index increased, and the water absorption index and viscosities decreased remarkably after enzymatic extrusion, however, the modification caused by α-amylase were dramatically eliminated with the increase of soybean content to ∼50%. Moreover, the addition of enzyme exhibited an improvement of the total phenolic/flavonoid content (TPC/TFC) and antioxidant capacities compared to traditional extrusion. The TPC/TFC retention of extrudate (ratios of 85/15 and 70/30%) attained over 90%, but dramatically decreased (72.91 and 67.81%, respectively) with soybean added to 75%, probably due to the great reduction of starch substrate for enzymatic hydrolysis.

Response surface methodology for evaluation and optimization of process parameter and antioxidant capacity of rice flour modified by enzymatic extrusion.

For the purpose of investigating the effect of enzyme concentration (EC), barrel temperature (BT), moisture content (MC), and screw speed (SS) on processing parameters (product temperature, die pressure and special mechanical energy (SME)) and product responses (extent of gelatinization (GE), retention rate of total phenolic content (TPC-RR)), rice flour extruded with thermostable α-amylase was analyzed by response surface methodology. Stepwise regression models were computed to generate response surface and contour plots, revealing that both TPC-RR and GE increased as increasing MC while expressed different sensitivities to BT during enzymatic extrusion. Phenolics preservation was benefited from low SME. According to multiple-factor optimization, the conditions required to obtain the target SME (10kJ/kg), GE (100%) and TPC-RR (85%) were: EC=1.37‰, BT=93.01°C, MC=44.30%, and SS=171.66rpm, with the actual values (9.49kJ/kg, 99.96% and 87.10%, respectively) showing a good fit to the predicted values.