Advanced Materials Research Vols. 554-556

Abstract: Recently, vacuum far-infrared radiation (VFIR) drying has received more and more attention because of its effective and successful applications in drying agricultural products, fruits and vegetables. Drying characteristics of VFIR drying on Cornus officinalis was studied in this research, and orthogonal regression experiment was designed and carried out. The results showed that with increase of heater’s temperature and decrease of chamber’s pressure, drying rate and loganin content increase, and the influence of heater’s temperature is more significant than that of pressure. With nonlinear programming analysis method, the optimized process parameters are obtained as heater’s temperature 98.6 oC and pressure 1000 Pa, and the corresponding drying time and loganin content are 250 min and 1.18%, respectively.

Abstract: This research aimed to study on the optimum condition for osmotic dehydration of pomelo. The experimental procedure was divided into 2 sections. For first section, the effect of sucrose solution concentration (50, 60, and 70 oBrix) on osmotic rate and moisture content of osmotic dehydrated pomelo were evaluated. After that, the effects of drying temperature (50, 65, and 80oC) on quality of osmotic dehydrated pomelo including, odor, texture, taste, and color were determined. The experimental results showed that the osmotic dehydration rate of pomelo were 6.4, 9.4, and 9.6 oBrix/hr when the pomelo was immersed in 50, 60, and 70 oBrix sucrose solutions, respectively. The moisture content of osmotic dehydrated pomelo which immersed in 70oBrix was lowest. The osmotic dehydrated pomelo that was immersed in 70 oBrix sucrose solutions and dried at 50oC has highest quality.

Abstract: A method was estimated to detect pentachlorophenol and sodium pentachlorophenolate in fishery products by gas chromatography with μ-ECD detector. Procedures of the method included extraction, alkaline stripping and derivatization. The pH of sample matrix was modified to 3-4 by nitric acid solution(nitric acid:water 1:1). Target compounds were extracted by hexane first and 0.2mol/L potassium hydroxide solution was used as stripping reagent to isolate pentachlorophenol from hexane. Acetic anhydride was taken as derivatizing reagent to convert target compounds into nonpolar ester compounds according to acylation reaction. Derivatized compound was extracted by hexane for the analysis of GC. The limit of detection is 2µg/kg . The average recoveries ranged from 73.01 to 104.68% spiked at 2.0,4.0,10.0µg/kg. And the relative standard deviations ranged from1.5 to 8.3%. The method can be used for the determination of pentachlorophenol and sodium pentachlorophenolate in fishery products,and it provides an rapid and acute method for food safety determination.

Abstract: The anti-fatigue activity evaluation was carried out with black soybean peptide in mice. The results show that, the middle and high dose active peptides can significantly （P＜0.01） prolong swimming time, blood lactic acid can be reduced notable （P＜0.01）, and improving the liver glycogen storage status greatly （P＜0.01） by infusing with black soybean peptide. The results suggest that black soybean peptide has obvious anti-fatigue effect, and the anti-fatigue action will improve by increasing dose.

Abstract: Muscle proteins degradation is one of the important manifestations relating to corruption of freshwater fishes during storage. In this paper, the changes in molecular weight distribution of grass carp muscle proteins during storage at nomal temperature were analyzed by SDS-PAGE and SEC-HPLC measurements. The results showed that the fish muscle proteins were always subject to changes during the whole process of storage, but significant changes of fish muscle proteins took place after 24 hours of storage. Particularly, the high molecular weight proteins were almost completely degraded after storage 24 hours, and the low molecular weight proteins were relatively stable but still undertaken more than 50% of degradation. Our results provide some new evidence for the change law of fish muscle proteins during early storage period.

Abstract: Hydrolysated peptides from kinds of proteins have been applied as natural ingredients in food industry, mainly due to their good functional properties. However, the fate of them under different processing conditions is rarely understood. In our study, changes of functional properties in porcine plasma protein hydrolysates (PPH) were evaluated in a free hydroxyl radical-mediated oxidation system. PPH was obtained by hydrolyzing porcine plasma protein with Alcalase for 5 h at pH 8.0, 55°C. When exposed to free radical-mediated oxidation, functional properties of PPH improved dramatically with growing oxidant concentrations and reaction time, especially at 20°C. Solubility, foaming capacity and emulsification of PPH increased significantly (P < 0.05) during early stage of oxidation, with solubility increasing from 83.1% (non-oxidized PPH) to 97.4%(20°C, 10mM H₂O_{Subscript text}2, 5 h), emulsifying activity index and foaming capacity rising form 1.24m2/g to 2.73 m2/g, and 144% to183%, respectively. Stability for emulsifying and foaming were also found to be reinforced. The improvements in functional properties of PPH helped to play theoretical basis for applying the peptides in food systems.

Abstract: A high-performance liquid chromatography method was set up for rapid determination of formaldehyde in dried bean milk cream. This thesis studies the Nash derivatization, derivative solubility, reaction time, amounts of Nash and derivative stability. The derivative is chromatographic separated by Agilent Zorbax Eclipse XDB-C18 column (4.6mm× 250mm, 5μm) and detected by index detector with VWD (412nm). The heater does not need the temperature-controlling system. A mobile phase was composed of acetonitrile and water (50:50, V/V) at a flow rate of 0.8 mL/min. Under the conditions of the above-mentioned test, the developed calibration curves displayed good linearity over a concentration range of 0.00 to 0.80mg/L, with a correlation coefficient exceeding 0.9998. Average spike recovery was found in a range of 88% to 91%, with a relative standard deviation (RSD) between 1.1% and 4.0%.The minimum detection limit of source is 0.013mg/Kg. The method can be used for rapid test on formaldehyde preservative in dried bean milk cream.

Abstract: In this study, the main microbe dynamic changes of cutlassfish (Trichiurus haumela) treated with composite natural preservatives under the cold storage (4±1) °C were studied by the methods of culture-dependent and denaturing gradient gel electrophoresis (DGGE) fingerprinting analysis based on the sequence of 16S rRNA V3 region gene, which provided the theory basis and reference to the composite natural preservatives’ mechanism and extended the shelf-life of aquatic products. The results showed that 13 kinds of bacteria were identified by the culture-dependent methods, the dominant bacteria belonged to Shewanella putrefaciens and Pseudomonas fluorescens. By sequencing analysis, 12 kinds of bacteria in main DGGE spectra stripe of cutlassfish. In the later periods, the specific spoilage organism (SSO) for the treatment group with composite natural preservatives and the controlled of cutlassfish were highly similar. Psychrobacter sp. was the main bacterium in the initial stage of the storage. With the extension of storage time, the proportion of Shewanella sp. and Pseudomonas sp. increased gradually and they took the place of Psychrobacter sp. to be the dominant bacteria in the process of storage. Thereinto, Pseudomonas fluorescens and Vibrio sp. both took high proportions in the process of storage. At the same time, composite natural preservatives had an obvious growth inhibition effects on the bacteria of cutlassfish such as Shewanella sp. and Pseudomonas sp..

Abstract: A novel strain, Bacillus fusiformis CGMCC1347, was utilized successfully to transform isoeugenol to vanillin and the product inhibition could be well avoided by using immobilized cells in the isoeugenol/aqueous biphasic system. The Bacillus fusiformis CGMCC1347 cells were entrapped into sodium alginate under conditions of 2.5% sodium alginate, 10% cells and 0.1 mol l-1 CaCl2. The optimum pH for free cells and immobilized cells were 4.0 and 3.5, respectively, and the optimum reaction temperature for both free and immobilized cells was 37 °C. The pH stabilities of free cells and immobilized cells were good at all investigated pH levels. For thermal stability, free cells were stable at 50°C60°C and the immobilized cells were stable at 50°C 80°C. The half-life of the immobilized cells was more than 25 d, comparing with less than 14 d for the free cells at 4°C.

Abstract: PEG 10000 / (NH4)2SO4 ATPS was applied to extract casein phosphopeptides. By studying on the partitioning behavior of CPPs in this system, it is concluded that the purification fold of CPPs could reach 7.09 when the system consisted of 20% PEG 10000 and 10% (NH4)2SO4.