Advanced Materials Research Vols. 781-784

Abstract: Whey proteins-extracellular polysaccharides (EPS) interactions system was builded,regarding whey proteins from buffalo milk and EPS as the research objects.Circular dichroism and fluorescence spectrum were used to investigate the interactions on the whey proteins-EPS system in the acidification process of buffalo milk yogurt. The main conclusions were as following:Electrostatic repulsion between whey proteins and EPS resulted in the β-sheet of secondary structure of whey proteins improving with 0.1% EPS added at pH7.0. Electrostatic attraction was present between whey proteins and EPS at pH6.0 and a great quantity of soluble complexes was formed at pH5.0.

Abstract: Strawberry is among the most perishable fruits and vulnerable to physical injuries and fungal invasion. To explore the effects of bacteriocin treatment on strawberry preservation, the inhibitory effect of bacteriocin produced by Lactobacillus on Botrytis cinerea was investigated. Meanwhile, the variation of weight-loss ratio, total soluble solids (TSS) and vitamin C content were determined after treatment of bacteriocin on field-grown strawberry. The results showed that spore germination of B. cinerea was significantly inhibited by bacteriocin at volume percentage of 20%, and bacteriocin inhibited increasing of weight-loss ratio, maintained more ascorbic acid, kept taste of strawberries. Therefore, bacteriocin is a kind of high efficiency natural preservatives and can be applied to the fruit preservation.

Abstract: The aim of this research was to investigate the inhibitory effect of bacteriocin for use as a biological control agent against Listeria monocytogenes in refrigerated meat products. And this bacteriocin was evaluated for their effectiveness as a preservative on pork. The bacteriocin-treated pork was compared with a control pork sample regarding the number of listeria colony count. After 10 days of storage at 4 °C, the population of Listeria monocytogenes was increased from 5.7×10⁵ to 3.7×10⁸ CFU/mL in control samples. In test samples, the population of Listeria monocytogenes underwent a slight increased from 5.7×10³ to 6.0×10⁵ CFU/mL. During 10 days of storage, the percentage of growth inhibition ranged from 82.6% to 99.8%, bacteriocin showed their inhibitory effect on Listeria monocytogenes. These results indicated that the studied bacteriocin exhibited bactericidal effect against Listeria monocytogenes strain at refrigerated temperatures, and bacteriocin could be used as antimicrobial agent to preserve the shelf life of refrigerated meat products.

Abstract: Food safety is an important issue related to the government regulatory authorities, food industry and food consumers. And the increasing use of food additives has become a matter of public and administrative concern, so an extensive safety evaluation on food additives must be carried out and the use of the additives in food should be controlled by law. In the United States, the Congress has entrusted the FDA with the responsibility to ensure that new additives to be used in foods and the foods the consumers purchase are safe. This paper discusses the supervision and management system of food additives in the United States. The conclusion is that FDA has developed a scientifically rigorous, sound and dependable system to assure the safety of food, thus a new food additive must be approved by FDA before it can be used in food. Management of food additives in the United States is also a helpful reference for government food control agencies in other countries.

Abstract: Listeria monocytogenes isolates recovered from retail foods were characterized by serotyping, genotyping using pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing. Six serotypes were identified among the isolates and the predominant serotype was 1/2a (42, 48.8%). PFGE differentiated the 86 isolates into 23 ApaI restriction patterns. Twenty-five (29.1%) of the L.monocytogenes strains exhibited resistance to at least one antimicrobial. Resistance to ciprofloxacin (17.4% of the isolates were resistant) and resistance to tetracycline (17.4%) were observed frequently.

Abstract: Cholesterol-lowering strains were obtained by high throughput screening technology and ortho-phthalaldehyde method. We used oxford cup method to screen again to obtain strains of high yield bile salt hydrolase and illuminate action mechanism of Lactobacillus reducing cholesterol. Screened six strains had the ability of high yield bile salt hydrolase and good ferment ability. The results of identifying bacteria species: strain KTxKL1J1 were Lactobacillus casei, strain Tx was Streptococcus thermophilus, strain KS4P1 were Lactococcus lactis subsp.lactis, where the last two bacteria were strain of high yield bile salt hydrolase to be few known in literature. This work showed that dissociation bile salts and cholesterol conjuncted sediments by bile salt hydrolase decomposing conjugated bile salts.

Abstract: The European Union and the United States have imposed different legal management on the genetically modified food. There are some disadvantages in the legal regime of China concerning the management of GMF which make the regal reform on the issue of GMF become necessary. To ensure food safety, China should take the legal regime of EU as reference and raise its standards for the market access of the GMF. The requirements of traceability and labeling for GMF should also be included in law. A centralized governmental department responsible for the issues of GMF should also be established.

Abstract: Salted Otolithes ruber with 80 (±5) g weight on dry basis were dried in the blast electric oven using different temperature (20, 30, 40 and 50°C) until the humidity fell down to 0.6 from 1.23 on dry basis. Drying processes were completed between 20-48h. In this study, experiment values were compared with predicted values obtained from twenty thin layer drying theoretical/ semi-empirical/ empirical equations. Models whose coefficient of correlation (R²) values are highest were chosen to be the best models. According to this, Midillis Model was defined as the most suitable model in which predicted value is closest to experimental data for 20°C level, Weibulls model was for 30°C level, Weibull distributions model was for 40°C level and Alibas model was for 50°C level.

Abstract: Yeast Z20 which screened from natural fermentation fig fruit wine as the original strain, through the 80s UV treatment and 25s microwave treatment, mutant strain UV-5 were selected. Its produced ethanol 13.6%, and it has fast fermentation speed, high wine production degree and the residual sugar quantity is little. After subculture 9 times, the results showed that the UV-5 strain has good genetic stability. Combined with the sensory evaluation results, the wine which fermentation by the strain UV-5 has high clarity, good flavor and good taste, so that the mutant strain UV-5 suitable for fermentation fig fruit wine as special yeast.

Abstract: Recently, molecularly imprinted solid phase extraction (MISPE) has been used more frequently separate drugs and natural substances. This modern separation methodologies require reliable tools that perform on a high level in terms of efficiency and reproducibility. The molecular imprinting technique is a reliable technique for the preparation of materials of predetermined selectivity. It is highly significant in research of the structure of enzyme, mechanism of receptor-antibody and analytical chemistry. Solid phase extraction can be used to isolate and pre-concentrate the analytes in complex samples. This technique is more rapid, simple, economical and environment-friendly than the traditional liquid-liquid extraction. The materials used in SPE are usually based on the non-specific binding of the targets, which often suffers some shortcomings, such as low specificity and selectivity. In recent years, solid phase extraction involving molecular imprinted polymer have been proved to be successful applications for its features of high selectivity, ease of synthesis, low cost for preparation and workability under different conditions especially that of harsh pH and organic solvents. In this work, the principles, application and development tends of MISPE will be reviewed and the disadvantages and limitation of the MISPE and future development direction are also briefly discussed.