Advanced Materials Research Vols. 781-784

Abstract: The conditions for nitrite reductase (NiRs) produced by Lactobacillus plantarum from salted fish were optimized. Enzyme activity of nitrite reductase was used as evaluation index. The results showed that the pH value had greatest influence on enzyme activity. The optimum conditions of producing nitrite reductase were inoculate quantity 4 %, pH 6.3, culture temperature 35 °C, incubation time 48 h. The enzyme activity of nitrite reductase reached to 89.672 U/mL, which increased by 71 % after optimization. This work provided the foundation for the research of enzymatic properties of nitrite reductase. This may be useful to the production of salted fish products.

Abstract: In this study, API 50CH strips and 16S rRNA gene sequence analysis were used to determine the species and genus of strain LD33 isolated from traditional dairy products, and the phylogenetic tree was constructed by MEGA4 software with Neighbor-Joining method analysis, the results showed that LD33 had a closest relationship with Enterococcus faecalis ATCC19433T (DQ411814), there was 100% sequence similarity between them.

Abstract: The ultrasonic extraction process parameter of Tengjiao (Zanthoxylum schinifolium) oil, such as time, ultrasonic power and ratio of solid to liquid, have been studied by signal and orthogonal experiments. The results show that, using vegetable oil as the extraction medium, the best processes were 13min, 1000W and 25:1.

Abstract: Aiming at cold-pressed oil cakes of linseed and sunflower seed, the pore fractal characteristics of microstructures have been studied. By combining Hagen-Poiseuille equation with fractal theory, a fractal permeability model for oil cake has been developed. The permeability of linseed and sunflower seed cakes under cold-pressed condition has been measured. It was found that the relative average errors are 12.8% and 16.8% for the soybean cake and sunflower seed cake respectively by comparing the result from the model calculation and experiment.

Abstract: Air-dried sausage (ADS) is a kind of Chinese traditional spontaneous fermented sausages, and is popular to consumers. In order to investigate the changes of volatile components from ADS during processing, solid phase micro-extraction (SPME) was employed to extract volatiles from samples of different processing stages. And then, volatile compounds were separated and identified by capillary gas chromatography-mass spectrometry (GC/MS). In this work, 19, 25 and 29 kinds of volatile compounds were identified from samples periodically taken at 0 d, 2 d and 7 d. 32 volatile compounds were identified in total during the entire process. The main volatile compounds during the processing of ADS were ethyl alcohol, hexanal, D-limonene, 2-pentanone and hexanoic acid ethyl ester. Branched-chain aldehydes: 3-methylbutanal and 2-methylbutanal were also detected and identified. The formation of these volatile compounds may be attributed to the added alcohol, spices, fat oxidation, amino acid metabolism, microbial activity and the interaction between these factors.

Abstract: Through determinated the changes of composition and activity during the fermentation period of buckwheat beer , then analyzed the relationship by used SAS 9.0 software. Determined the monomer flavonoid, monomer phenolic acids by HPLC, antioxidant activity by against the ABTS and DPPH. The results show that the amount of total flavonoid (from 0.607±0.047 g·L^-1 to 0.519±0.038 g·L^-1 ), total phenolic acids (from 0.690±0.060 g·L^-1 to 0.395±0.034 g·L^-1) change during fermentation . Tartary buckwheat beer exhibits strong DPPH (103.904±0.361 VCEAC mg·L^-1) and ABTS (25.018±0.268 VCEAC mg·L^-1) radical scavenging activities.The rutin, quercetin, ferulic acid, caffeic acid, protocatechuic acid,and p-coumaric acid show a downward trend, however,the isoquercitrin, gallic acid display the rising trend. At the same time,the regression equation as Y₂ ( Total phenolic) = 0.31595 + 2.10834X₅ (Quercetin)(P<0.05), Y₃ ( ABTS[VCEA ) = 47.75299 23.78253X₈ (Ferulic acid)(P,0.05).

Abstract: To reuse the waste of fishery resources in a preliminary study, we have described changes in extractive components during spontaneous fermentation of fish sauce using eel intestines. This study was aimed at investigating the chemical analysis of extractive components from fermented eel intestines with a view to using it as a food condiment. Fish sauce was produced via fermentation of by-products (intestinal) of processed eel with 35% (w/w) of salt for 180 days. During 180 days of fermentation, the pH decreased to approximately 4.8, and the overall trend of total nitrogen, amino acid nitrogen, non-enzymatic browning index and total volatile basic nitrogen were increasing. The changes and the trend mentioned above indicated that it was a practical method to produce fish sauce using eel intestines, but the spontaneous fermentation cycle was long (more than 6 months).

Abstract: To generate a group-specific monoclonal antibody (McAb) against danofloxacin (DANO), enrofloxacin (ENR) and ciprofloxacin (CIP), glutaraldehyde was used to link the presentative hapten of CIP to the immunogen and coating antigen, respectively, leaving the common structure of these 3 drugs exposed in both conjugates as a major antigenic site. Consequently, a McAb (6D3) with high cross-reactivity to this three antibiotics has been obtained by using hybridomas technique. In a biotin-avidin mediated enzyme-linked immunosorbent assay, the IC₅₀ values for DANO, ENR and CIP were 5.1, 4.5 and 4.2 ng mL^-1, respectively. The ELISA was used for the detection of spiked DANO and ENR+CIP in milk. The recoveries ranged from 74.1 to 92.4% and coefficients of variation were in a range of 6.6-11.9%. The accuracies and sensitivity of the method were good for simultaneous analysis of the 3 drugs in milk after a simple sample extraction process.

Abstract: The degradation effectiveness and reaction kinetics of representative organophosphorus (OP) pesticide in a packed-bed plasma reactor have been studied. Important parameters, including peak voltage, pulse frequency, gas-flow rate, initial concentration, diameter of catalyst particles, and thickness of catalyst bed which influences the removal efficiency, were investigated. Experimental results indicated that rogor removal efficiency as high as 80% can be achieved at 35 kV with the gas flow rate of 800 mL/min and initial concentration of 11.2 mg/m^3. The removal efficiency increased with the increase of pulsed high voltage, and pulse frequency, the decrease of the diameter of catalyst particles and the thickness of catalyst bed. Finally, a model was established to predict the degradation of the rogor, which generally can simulate the experimental measurements to some degree.

Abstract: Essential oil form Myrica rubra root was investigated for their chemical compositions and antimicrobial activities against foodbone pathogens. Gas chromatography-mass spectroscopy (GC-MS) for the compound identification was used. Antimicrobial activities for the essential oil against 5 food borne pathogens were carried out by disc diffusion, microdilution agar plate and bioautography methods. Principal components of the essential oil were 5-hydroxycalamenene (74.66 %) and phytol (7.74%). This essential oil was particularly effective against Bacillus cereus and Listeria monocytogenes with minimal inhibition concentration (MIC) 0.004% and 0.03%(v/v), respectively. Interestingly, the antimicrobial activities of the root oil apparently were mainly correlated with its 5-hydroxycalamenene content. Given that this product has high antimicrobial activity, it might have food preservative potentials.