Guo Qin Liu

Enzymatic Synthesis of Naringin Palmitate

Naringin esters are paid more attention in medical and functional food industry than naringin due to their higher stability and solubility in lipidic environments. Naringin palmitic acid esters were enzymatically synthesized with naringin and palmitic acid. The effects of solvent type, temperature, concentration and types of enzymes and the molar ratio of substrates on the conversion of naringin were investigated. Novozym 435 performed higher catalytic ability in tert-amyl alcohol in the esterification of naringin with palmitic acid. The conversion yield of naringin increased with the increase of temperature (30-70°C) and of the concentration of enzyme. The structure of the naringin palmitate was characterized by FT-IR, 1H-NMR and HPLC-MS. 1H-NMR spectroscopic analysis indicated the presence of an ester bond on the C-6 of the glucose moiety of naringin molecule.

Emulsifying and Foaming Properties of Wheat Gluten Influenced by High Pressure Microfluidization

The changes in emulsifying and foaming properties of wheat gluten treated by dynamic high pressure microfluidization (DHPM) were identified. Solutions of wheat gluten (4%, w/w) in water or in pH=2 aqueous solution were treated by various pressure (0, 40, 60, 80, 100 MPa) microfluidization. It was found that DHPM treatment could effectively improve the emulsifying property and foam stability of wheat gluten in water, but decrease the foaming capacity of wheat gluten in water and emulsifying and foaming properties of wheat gluten in pH=2 aqueous solution. These results may be useful to the food processing industry.

Synthesis of Epoxidized soybean Oil via phase transfer catalysis

In the system of heteropoly acid [π-C5H5NC16H33]3[PO4(WO3)4], H2O2 (30 %, w/w), polyethylene glycol, 1,2-dichloroethane, soybean oil under went epoxidation reaction smoothly via reaction-controlled phase transfer catalysis. Effects of the amount of interfacial active agent, H2O2, catalyst and reaction time were investigated and the optimized reaction conditions were as follows: 10 g of soybean oil, 0.3 g of [π-C5H5NC16H33]3[PO4 (WO3)4],8 ml of H2O2 (30 %, w/w), 5.0 ml of PEG, 30 g of 1,2-dichloroethane, and the reaction temperature was 65 °C and reaction time was 3.5-4.0 h. Under these optimized conditions, an epoxy value of 6.30 % and a yield of 90 % were obtained. Hence, it is an environmental-friendly and effective way to synthesize epoxidized soybean oil.

Ultrasound-Assisted Acceleration of Soybean Oil Epoxidation and the Interfacial Tension Study

This work was to reduce the epoxidation time of soybean oil with the assistance of ultrasonic irradiation and a kind of fatty acid as the catalyst in the presence of formic acid as the carrier of reactive oxygen. The operational parameters affecting the epoxy value of soybean oil, such as the amount of fatty acid and the ultrasonic frequency, ultrasonic power and reaction time were studied. And the interfacial tension of the aqueous-oil phase was decreased with the catalyst fatty acid adding or the assistance of ultrasonic irradiation, therefore the reaction rate could be accelerated. The maximum epoxy value of epoxidized soybean oil was 17.19% increased compared with the epoxy value that treated by non-ultrasound assistance in the same reaction time. Experimental results indicated that the epoxy value could be enhanced under the ultrasonic irradiation assistance, where the reaction time could be effectively reduced.

Antioxidant Activities of Soluble Dietary Fiber Extracted from Brewers’ Spent Grain

Brewers’ spent grain (BSG) is the most common by-product of the brewing industry, contains about 16.8% cellulose, 28.4% non-cellulosic polysaccharides and 27.8% lignin, which is a good raw material for industrial production of soluble dietary fiber (SDF).The antioxidant activity of crude dietary fiber (CDF) and grade dietary fiber (GDF) isolated from BSG was investigated in vitro. The scavenging hydroxyl radical capability of CDF and GDF was respectively reached to15.4% and 69.2% at the concentration of 0.1mg /mL. DF concentration from 0.02mg /mL to 0.1m g /mL was used. The scavenging capability of CDF and GDF to superoxide anion radical was increased from 10.68% and 12.33% to 35.78% and 78.39%. Both of the two DF showed some effect in scavenging superoxide radical and 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) radical with the concentration increase. The result showed that BSG DF can be used as a good additive with some functionality.

Optimization of HS-SPME for GC-MS Analysis of Volatiles Compounds in Roasted Sesame Oil

This paper was to develop a simple and rapid headspace solid-phase microextraction (HS-SPME) method coupled with gas chromatography–mass spectrometry (GC-MS) for the determination of volatiles compounds from the roasted sesame oil (RSO). A HP-5MS capillary column (30 m × 0.25 mm I.D. × 0.25 mm film thick) was used for GC-MS, and a 50/30 μm divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was used to extract volatiles compounds. The condition was optimized by varying the sample-to-headspace ratio (0.5-2.5 g/15 ml), extraction time (10-50 min) and Splitless time (0.5-4 min). The results showed that the optimal operating conditions occurred at (extraction temperature:40°C, sample-to-headspace ratio: 1.5 g/15 ml, extraction time: 40 min, Splitless time: 1 min) for the analyze method.

Effect of High Pressure Microfluidization on Secondary Structure of Wheat Gluten in Different Solvents

Far-UV circular dichroism (CD) spectroscopy was used to study the conformation of wheat gluten protein treatmented by dynamic high pressure microfluidization (DHPM), acid treatment and its comprehensive treatment in two solvents. The results showed, the secondary structure of control sample are mainly consist of α-helix and random-coil in phosphate-buffered saline (PBS) and phosphate buffered solution with SDS(SDS), the secondary structure of control sample are mainly consist of β-Sheet and random-coil. The CD data also showed that SDS interacts with the gluten protein and modifies the protein conformation, which switched the conformation from α-helix and β-Turn to β-sheet and random-coil. However, the CD analysis also indicated that some of the ordered structures of α-helix, β-Turn and β-sheet were destroyed and converted random-coil coped with acid in two solvents, in other words, the acid treatment can directed change the secondary structure. Furthermore, the effect of comprehensive treatment (DHPM plus acid) is not equal to the simple sum of the individual treatment effect.

Functional Properties of Ultrasonically Treated Wheat Gluten

Ultrasonic was employed to improve the functional properties of wheat gluten. The results showed their solubility, emulsifying capacity and emulsion stability index of ultrasonically treated wheat gluten gradually increased as the ultrasonic power and treatment time increase, when ultrasonic treated for 20min at 240W, the solubility, emulsifying capacity and emulsion stability reached the maximum, then the solubility slightly decreased when the ultrasonic power exceeded 240W. However, the forming capacity and foam stability of ultrasonically treated gluten samples gradually increased with ultrasonic power and treatment time increasing. Gel Permeation Chromatography (GPC) observations revealed that the molecular weight of gluten decreased as the ultrasonic power increased, implying that the molecular of wheat gluten was broken by ultrasonic. Lower molecular weight of wheat gluten showed better functional properties.

Antioxidative Activity and Functional Properties of Hydrolysates of Camellia Seed Meal Treated with Trypsin

Antioxidative activity and functional properties of hydrolysates prepared from defatted camellia seed meal(DCSM), using trypsin, with a degree of hydrolysis(DH) of 21.69% were determined. At this DH, the hydrolysates show the highest hydroxyl and superoxide anion radical scavenging activity (over 69.15 % and 78.22%, respectively). The functionalities of hydrolysates such as solubility, water-holding capacity,emulsifying activity, foaming capacity and foaming stability are remarkably improved at all test pH range. These results indicate that the DCSM hydrolysised by trypsin to produce hydrolysates with desirable antioxidative activity and functional properties.

Preparation of Sea Buckthorn Oil-Plga Microspheres via the Emulsion-Solvent Evaporation Process Coupling Ultrasonic Treatment

The optimal preparation conditions of sea buckthorn oil-poly (lactic-co-glycolic acid) (PLGA) microspheres were studied via the emulsion-solvent evaporation process coupling ultrasonic treatment, using polyvinyl alcohol (PVA) as the emulsifier, PLGA as the wall material, a mixture of dichloromethane and ethyl acetate as the oil phase. The research discussed the effects of the PVA concentration, the PLGA dosage, ultrasonic power and ultrasonic time on comprehensive quality index (S) of sea buckthorn oil-PLGA microspheres. The orthogonal experimental design L9 (34) with the factor analysis was applied to optimize preparation conditions. The experimental date showed that the optimal technology preparation conditions for sea buckthorn oil-PLGA microspheres were as follows: the concentration of PVA 0.125 g/ml, PLGA loading 125 mg, ultrasonic time 10 min, and ultrasonic power 180W. It resulted in sea buckthorn oil-PLGA microspheres that were in more regular and smaller shape, and with a better comprehensive quality index.