Effect of sodium nitrite and sodium chloride on growth of lactic acid bacteria.

The effect of NaNO2 and NaCl on the growth of 24 lactic acid bacteria strains isolated from vacuum-packed cooked ring sausages were examined by analyzing different growth parameters with Bioscreen. NaNO2 had a very limited effect on the growth of lactic acid bacteria at 50 and 100 mg/l but at 400 mg/l a more pronounced inhibitory effect was found. Bacterial growth was enhanced by 1-2% (w/v) of added NaCl, while NaCl concentrations above 3% (w/v) had a clear inhibitory effect. Leuconostoc isolates seemed to be more sensitive to sodium nitrite and sodium chloride than homofermentative lactobacilli strains. Among homofermentative lactobacilli, the strains resembling Lactobacillus curvatus were more sensitive to NaCl than those resembling Lactobacillus sake.     

紫外吸收法、电导率法检验大白菜种子活力的研究

通过人工老化种子和不同年代种子具有的活力不同,以发芽指数为活力参考标准来探索种子浸泡液电导率测定法和紫外吸收测定法是否适合大白菜种子活力的快速检测.结果表明:大白菜种子紫外区随着波长的缩短吸收值增大,但经玻璃比色杯滤过后会在286 nm下显示吸收峰,随着种子活力的降低286 nm下的OD值呈上升趋势,对发芽率高于85％的种子适用,而对于活力过低的种子检验不可靠;随着种子活力的降低电导率呈上升趋势,但对活力差异较小的种子间检验不可靠.因此,对发芽率合格范围内的种子可以根据286 nm(玻璃比色皿)紫外吸收值评价大白菜种子活力的高低,其他的种子可参考电导率值比较种子活力.     

一种检测乳过氧化物酶方法的建立

【目的】建立一种简便、快速、精确的乳过氧化物酶（LP）检测方法。【方法】以ABTS为底物，利用动力学方法，建立了检测LP含量的ABTS法，并以优化后的体系检验ABTS法的精确度。【结果】以ABTS法检测LP含量的最佳反应条件为：吸收波长416nm，作用时间100s，pH5．5，ABTS浓度2mmol／L，H2O2浓度5mmol／L，工作温度25℃（室温）。经检验，该法的批内变异系数为2．39％，批间变异系数为3．42％，相关系数（R2）为0．9953，准确误差均未超过5．00％。【结论】以ABTS法检测LP精密度和准确度均较好，且操作步骤比较简便、快速，实现了对LP的简便、快速、精确检测。     

基于稳态空间分辨光谱的猪肉肌红蛋白检测方法

The objective of this work was to determine the concentration of myoglobin in fresh pork meat and establish a fast non-invasive method using steady spatially-resolved spectroscopy (SRS). The concentration of myoglobin was calculated based on absorbance coefficients at 640, 760, 800, 850 nm. The results showed that the value of myoglobin using SRS was significantly correlated (r2=0.955) to traditional methods with the accuracy of 3.6%F.S. The results showed that the concentration of myoglobin can be measured by using near infrared steady spatially-resolved spectroscopy.     

塞内加尔达喀尔地区沙丘土壤中有机添加物的荧光表征及去向

The application of organic amendments on soils poor in organic matter (OM) can improve long-term soil fertility, but may also enhance the mineralization of native soil organic matter. Three organic amendments, compost, sewage sludge and horse manure used by urban market gardeners in Dakar, Senegal were analyzed for their OM maturity. Their fate was evaluated in a 45-d agronomic trial in a sandy Arenosol with lettuce. In each case, water-extractable organic matter (WEOM) and humic-like substances (HLS) were isolated from raw amendments and amended soils, and characterized using ultraviolet-visible (UV/Vis) spectroscopy. Results highlighted the general more aromatic character of HLS and WEOM fractions extracted from compost compared to the other two amendments. When applied to soils, however, these differences were not clearly observed. The aromaticity and humification degree of the labile fraction (WEOM) increased with depth in the first 30 cm for all amendments. This indicated the high lixiviation rates that fresh OM underwent in the studied sandy soil. Finally, a statistical analysis of the results was able to discriminate between surface and deeper horizons and between amended- and non-amended soil samples. Spectroscopic indices showed indeed strong increase/decrease with depth linked with the mineralization/humification processes that the fresh OM from amendments underwent during the 45 d of the agronomic trial. This study highlights the potential of spectroscopic techniques to study agricultural amendment organic matter fractions and their fate in soils.     

醇提水沉与水提醇沉对桉叶多酚提取物抗氧化活性的影响

本文以氧化自由基吸收能力(ORAC)、DPPH自由基清除能力以及多酚含量为指标,探讨醇提水沉法、水提醇沉法对桉多酚提取物抗氧化性的影响.结果表明,醇提水沉法上清液组分ORAC值高于其沉淀组分,也高于水提醇沉法的沉淀组分和其上清液组分.醇提水沉上清液组分多酚含量以及清除DPPH自由基活性均强于其他组分.因此可得醇提水沉法优于水提醇沉法,这对桉多酚后期的分离纯化起到指导作用.     

Angiotensin Converting Enzyme and Dipeptidyl Peptidase-IV Inhibitory,and Antioxidant Activities of a Blue Mussel (Mytilus edulis) Meat Protein Extract and Its Hydrolysates

ABSTRACT

Protein extracted from mussel processing coproducts was hydrolyzed with four different food-grade enzyme preparations and assessed for angiotensin converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) inhibitory and oxygen radical antioxidant capacity (ORAC) activities. All hydrolysates tested showed higher activity than the intact protein. ACE and DPP-IV IC₅₀ values in the range 1.13–3.34 and 0.33–2.43 mg mL^?1, respectively, and ORAC values in the range 66.26–121.56 µmol trolox equivalents g^–1 were obtained. These results suggest that some of the mussel meat protein hydrolysates may have potential as functional food ingredients for the management of diseases such as type II diabetes and hypertension.     

Purification and Characterization of an Antioxidant Protein from Pearl Oyster (Pinctada fucata martensii)

Protein from pearl oyster (Pinctada fucata martensii) was purified and characterized. Results showed that the pearl muscle protein (PMP) was composed of a single polypeptide with a molecular weight of approximate 11.6 kDa and contained 95.1% of the protein and 4.92% of the carbohydrate of the oyster. The polypeptide appears to be a glycoprotein, since the Fourier transform infrared (FTIR) spectroscopy of the PMP shows the typical characteristics of protein and polysaccharides. The denaturation temperature of the PMP was 81.3°C by differential scanning calorimetry. Circular dichroism spectroscopy showed that the PMP has a highly ordered structure. The PMP (200 μg/mL) showed a high oxygen radical absorbance activity (ORAC) of 6.57 μmol Trolox/μmol protein. Its antioxidant activity was stable at temperatures from 30–80°C and pH 2–10. The antioxidant activity was significantly inhibited by Zn²⁺, Ca²⁺, and EDTA and enhanced by Mn²⁺. The results suggest that the PMP could be used as a potential natural antioxidant.     

芽胞杆菌菌体浓度的快速检测方法研究

为了快速检测芽胞杆菌的菌液浓度,采用分光光度法测定蜡状芽胞杆菌的菌液浓度,代替传统常规费时费力的生物细胞测定法。本研究以不同pH值下培养的模式菌株蜡状芽胞杆菌为例,通过可见光分光光度法测定不同pH值菌液的吸光度,分别以水和培养基作为空白对照,并与其对应的菌体浓度进行比较分析。利用生物统计软件DPS分析蜡状芽胞杆菌菌液浓度(Y)与其吸光度(X)（以水为空白对照）之间有着极好的相关性,其测定的吸光度可以作为快速地检测芽胞杆菌菌体浓度的指标。综上所述,本研究结果证明吸光度法可以代替细胞计数法作为芽胞杆菌的菌体浓度生长变化的指标,且此方法简便、快速、可靠。