Jiachun Zhou

Characterization and activity of anthocyanins in Zijuan tea (Camellia sinensis var. kitamura).

Zijuan tea is a new cultivar produced in Yunnan province of China. Unlike most tea cultivars, Zijuan tea is anthocyanin-rich. The composition and antioxidant activities of anthocyanins of Zijuan tea were studied for the first time in this paper. Anthocyanins were extracted with acidified methanol and quantified as 707 ± 28 μg/g of dry weight (cyanidin-3-O-β-D-glucoside equivalent) by high-performance liquid chromatography (HPLC) analysis. Four anthocyanins were successfully identified after Amberlite XAD-7HP adsorption column chromatography and octadecyl silane (ODS) flash chromatography. Among the four, delphinidin-3-O-β-D-galactoside (1) and cyanidin-3-O-β-D-galactoside (2) were confirmed by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) and HPLC. Delphinidin-3-O-β-D-(6-(E)-p-coumaroyl) galactopyranoside (3) and cyanidin-3-O-β-D-(6-(E)-p-coumaroyl) galactopyranoside (4) were characterized by the high-resolution time-of-flight-mass spectrometry (HRTOF-MS) and nuclear magnetic resonance (NMR) spectrometry. The antioxidant activities of compounds 3 and 4, which composed approximately 75% of the total anthocyanins content in HPLC analysis, were evaluated by DPPH and FRAP assays. Results showed that both had higher antioxidant activities than commercial antioxidants butylated hydroxytoluene (BHT) used as one of controls in these assays.

Kinetics and equilibria of the chromatographic separation of maltose and trehalose

Trehalose, a nonreducing disaccharide, has been extensively applied to food, cosmetics, and pharmaceutical goods. The resultant solution of trehalose prepared by enzymatic methods includes high amounts of maltose. However, it is quite difficult to separate maltose and trehalose on an industrial scale because of their similar properties. In this paper, a high-performance resin was selected as a stationary phase to separate trehalose and maltose, and the resolution of these sugars was 0.59. The potential of a cation exchange resin was investigated as the stationary phase in separating trehalose and maltose using deionized water as the mobile phase. Based on the equilibrium dispersive model, the axial dispersion coefficients and overall mass transfer coefficients of maltose and trehalose were determined by moment analysis at two different temperatures, 50 and 70°C. Other parameters, including the column void and the adsorption isotherms, were also determined and applied to simulate the elution curves of trehalose and maltose. The simulated results matched the experimental data, validating the parameters. The optimized parameters are critical to the chromatographic separation of trehalose and maltose on an industrial scale.

Recovery of beta-Amylase by Hybrid UF Membranes from the Soy Whey Wastewater

Large-scale manufacturing of soybean proteins results in huge volume of “wastewater” which contains substantial amount of β-amylase, and the recovery of β-amylase has potential high value. In order to evaluate the feasibility and effect of novel hybrid Ultrafiltration (UF) method against the normal method, the pretreated effluent was concentrated by a low molecular weight cut off (MWCO) 3 kDa UF membrane firstly, terminated at Volume Concentration Ratio (VCR) of ca.7. To this UF retentate was then precipitated by adding 1.2M (NH4)2SO4 to remove other proteins. The supernatant obtained following centrifugation was purified through a further higher 30 kDa MWCO UF membrane, which ended at VCR of ca.10. The prepared was purified 4.8 fold, with an enzyme activity concentration ratio of 61, and is associated with 74% combined recovery for the enzyme activity, giving a final specific activity of 14 U/mg (674 U/mL), of which enzyme activity is fully enough for the industrial applications. Preliminary data of this research indicate that this could be an effective method for treating kinds of related protein wastewaters.

Physicochemical Characteristics of Edible Bird’s Nest Proteins and Their Cooking Processing Properties

Abstract Edible bird’s nest (EBN) has a high nutritional and medicinal value. In this study, physicochemical and processing properties of EBN proteins were investigated for better application of EBN. EBN proteins were extracted by combination of several methods. Electrophoresis showed that EBN contained proteins with molecular weight of 128, 106, 80, 55, 43, and 34 kDa. The denaturation temperature of EBN proteins was 62.5°C and heating promoted hydrophobicity as well as dramatically affecting the gel microstructure of EBN proteins. EBN proteins also showed excellent emulsifying activity and stability while their foaming properties were not good enough.