Advanced Materials Research Vols. 781-784

Abstract: A method for the determination of residues of malachite green and leucomalachite green in Chinese soft-shelled turtles (Pelodiscus sinensis) muscle by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established. The samples extracted with acetonitrile, and clean up on a neutral alumina SPE cartridge, separated on a C₁₈ column using acetonitrile-5mmol/L ammonium acetate as mobile phase, and then detected under multiple reaction monitoring mode.The method showed a good linearity for all the analysts over the range of 0.1-50μg/L with r²0.999.The detection limits of malachite green and leucomalachite green were 0.10 and 0.12μg/kg respectively. The recoveries ranged from 84.9 % to 93.8% at three spiked concentrations with the relative standard deviations lower than 5%. The results shows that this method has the advantages of easy to operate, fast to perform,with high sensitivity and accuracy, and it is suitable for detection of residues of malachite green and leucomalachite green in Chinese soft-shelled turtle (Pelodiscus sinensis).

Abstract: To explore a rapid and non-destructive method for measuring titratable acidity in Gannan Navel Orange, near infrared spectroscopy combined with partial least square method was adopted for building a prediction model. Multiple statistical analysis results show that when the optimal spectral region (950-1330nm) was selected for modeling, the correlation coefficient of the validation set is 0.9085, and RMSECV is 0.0243g/100g. This technique using near infrared spectroscopy is rapid, convenient and nondestructive, and may potentially become a strong tool for the quality evaluation and fruit sorting of navel oranges.

Abstract: An indigenous bacterial strain high active for fermentative production of white pepper was isolated from soil samples. Initially isolates were screened by yellow ring and the speed of color change in the plating medium. Then, the secondary screening was done through the abilities of the strains for the retting of green pepper. The selected strain WC17 showed excellent activity for the retting of the green pepper.The produced white pepper by this method achieved superior level. Volatile oil and piperine contents of the product were 3.26% (v/w) and 4.15% (v/w), respectively. The microbial contamination was no more than 1.3×10² per 1g. Physiological, biochemical characteristics and 16SrDNA sequencing indicated that the isolated strain WC17 was belonging to Bacillus cereus group. This screening could be used as a rapid and reliable method for the isolation of bacterial strain for fermentative production of white pepper.

Abstract: In order to improve EAI and ESI of Soybean protein isolate (SPI), Glycosylation modification was studied by adding lactose and the operation conditions for modification were established by single factor experiment. On the basis, Box-Behnken model was used to optimize technological conditions, test and analyze the EAI and ESI of modified products under various conditions. The best glycosylation modification was as follows: the augmenter of lactose was 6.9%, reaction temperature was 70.5°C, reaction time was 38.6h, and the EAI and ESI could achieve 0.754 and 24.00 which was 2.32 and 2.67 times of the unmodified SPI. The experiment proved that the modification technology can effectively increase EAI and ESI of SPI.

Abstract: This experiment was conducted to assess the antioxidant efficacy of Seabuckthorn (Hippophae rhamnoides) leaves extracts (SLE) in raw pork patties during chilled storage at 4 °C for 0-7 days. The pork patties were analyzed periodically for chemical characteristics, such as pH value, colour, thiobarbituric acid-reactive substances value (TBARS), peroxide value (POV) and protein carbonyls content. Compared with the control, SLE treatments significantly decreased the TBARs and POV values and carbonyls formation of pork patties in a dose-dependent manner (P < 0.05), which showed that the SLE significantly inhibited lipid and protein oxidation. The results of this study suggested that the antioxidant activities of seabuckthorn leaves extracts could have great effect on improving the quality characterizes of pork patties and prolong its shelf life.

Abstract: Antioxidant peptides crude product from Pinctada Fucata desalination technology by C18 chromatographic column was studied. The desalination rate and the antioxidant activity were used to analyze the effect of desalination conditions. The results show that the optimum conditions for desalting are loading 2ml of sample with concentration of 100 mg/ml, flow rate of 2 ml/min, 0.1% TFA as mobile phase with pH 6.5 in 0-4.5min and 80% methanol in 4.5-30min. Under these conditions, the desalination rate is 68.75% and the peptide recovery rate is 76.53%. The inhibitory content (IC₅₀) expressed by antioxidant peptides is 11.421mg/ml in the system of DPPH radical.

Abstract: To investigate the pure conditions of exopolysaccharides produced by Lactobacillus paracasei KL1-Liu from Tibetan Kefir, and to analyse the structure, we used Multi-level single-factor test to purify EPS by Sepharose CL-6B. And the purity of EPS was detected by UV scan and high performance liquid chromatogram (HPLC). EPS molecular weight and monosaccharide composition were determined by HPLC. Results: Adoption phosphate buffer gradient elution 0.02-0.10 mol/L, the velocity 0.25 mL/min, the sample concentration 1.0 mg/mL, the sample capacity 1.0 mL. Under this purification conditions, components EPSa and EPSb were obtained. The purities of EPSa and EPSb were 82.82% and 91.74% respectively, which were 1.4 and 1.5 times of the pre-purification. Purity Test results showed that EPSa and EPSb polysaccharide were single components, basically no nucleic acid and protein in them. Structural analysis revealed that the molecular weight of EPSa and EPSb were 4.60×10⁴ Da and 2.12×10⁴ Da detected by HPLC. EPSa monosaccharide components were glucose and rhamnose, and the molar ratio was 1:0.68. EPSb were composed of glucose, xylose and rhamnose, and the molar ratio was 1:0.77:0.69.

Abstract: In this research, Dendrobium officinale was studied at different storage temperatures for water loss, soluble solids, titratable acids, membrane permeability, malonaldehyde (MDA) changes. Results showed that weight loss rate was positively associated with storage temperature, the higher of storage temperature, the weight loss more severe and the quality of dendrobium stem was lower. Dendrobium’s titratable acid content, soluble solids content changed slowly than 10°C, 20°Cwhen it was stored in 0°C temperature but their content were higher than 10°C, 20°C samples . Storage temperature is positively correlated with the change of membrane permeability and malonaldehyde (MDA) as the extension of storage time, high temperature will damage the membrane permeability of Dendrobium and at the same time the production of membrane lipid peroxidation caused.

Abstract: Tilapia protein hydrolysates (TPH) were obtained by enzymatic hydrolysis of tilapia meat using papain, and then the TPH binded with copper at various mass ratios of TPH to CuCl₂ (5:1, 10:1 and 20:1) to obtain complex I, complex II and complex III, respectively. The copper-binding rate, antioxidant properties, and FTIR spectrum of the complex were investigated. It was found that the copper-binding rate increased with the increase of mass ratios (TPH/CuCl₂) from 5:1 to 20:1. The DPPH radical scavenging activity and reducing power activity of TPH were higher than that of the complexes. However, the lipid peroxidation inhibition activity was improved after TPH binded with copper. It was also found that the antioxidant activities of complex III were highest in the complexes. FTIR spectra demonstrated that some sites such as amino nitrogen atoms in TPH could bind with copper to form the complex.

Abstract: The contents of free amino acids(FAAs) in Parapenaeopsis hardwickii, Penaeus vannamei and Macrobrachium nipponensis was analyzed by using the automatic amino acid analyzer in this study. The results show that the sequence from the highest to the lowest in total amount of FAAs is Parapenaeopsis hardwickii, Penaeus vannamei and Macrobrachium nipponensis. SPSS(19.0) results indicate that except for Cys, Lys and Thr, FAAs in these three shrimps are significant different (p<0.05), and all of them have a high concentration of Arg, Gly and Pro and a low concentration of Asp and Cys. The content of Gly in shrimp is higher than that of crab and oyster. Both Arg and Gly significantly contribute to the taste of the three shrimps, Glu and Pro play an important role in the flavor of Parapenaeopsis hardwickii and Penaeus vannamei, while not as significant as in the taste of Macrobrachium nipponensis. Composition modes of FAAs which make major contributions to flavor in marine shrimps, Parapenaeopsis hardwickii and Penaeus vannamei, are similar, but different from freshwater shrimp, Macrobrachium nipponensis.