超高效液相色谱-串联质谱法同时测定玉米中9种真菌毒素

为高效检测玉米中的生物毒素,采用80％乙腈-0.1％甲酸水溶液提取、QuEChERS法净化、甲醇-0.1％甲酸+5 mmol/L甲酸铵水溶液经C18柱梯度洗脱分离、电喷雾正负离子同时扫描并多反应监测模式采集数据的综合方法,对玉米中黄曲霉毒素B1、B2、伏马毒素B1、B2、B3、呕吐毒素、3-乙酰脱氧雪腐镰刀菌烯醇、15...     

Evaluation of Natural Antioxidants in Frankfurters Containing Chicken and Pork

Three natural antioxidant systems, tocopherol, extract of rosemary, a tocopherol and rosemary combination, and BHA/BHT were evaluated in frankfurters prepared from chicken and pork. Thiobarbituric acid numbers of refrigerated bulk and vacuum packaged samples stored in darkness for up to 18 days indicated that natural tocopherols provided significantly more protection than controls containing no antioxidant and were as effective as BHA/BHT in retarding oxidation. All bulk-packaged frankfurters except those containing BHA/BHT and tocopherols were inedible after 18 days. Color values indicated no evidence that any treatment provided better color stability.     

Extending the shelf life of fresh ewe’s cheese by modified atmosphere packaging

This study evaluated the effect of modified atmosphere packaging (MAP) in extending the shelf life of a fresh ewe’s cheese stored at 4 °C for 21 days. Three batches were prepared with 20, 30 or 50% CO₂ with N₂ as filler gas. MAP controlled well the microbial growth, and the best result was obtained with 50% CO₂. Pathogens were not detected in any sample. Softening of cheese was best reduced by 30% or 50% CO₂. The sensory characteristics of the cheeses markedly decreased during storage. Only the sample stored with 50% CO₂ obtained an overall score above the acceptability at 14 days.     

Confocal microscopy study of the distribution, content and activity of mitochondria during Paracentrotus lividus development

In the present paper we applied confocal microscopy and fluorescence technologies for studying the distribution and the oxidative activity of sea urchin (Paracentrotus lividus) mitochondria during development, by in vivo incubating eggs and embryos with cell‐permeant MitoTracker probes. We calculated, by a mathematical model, the intensity values, the variations of intensity, and the variation index of incorporated fluorochromes. Data demonstrate that mitochondrial mass does not change during development, whereas mitochondrial respiration increases. In addition, starting from 16 blastomeres stage, some regions of the embryo contain organelles more active in oxygen consumption.     

PREPARATION OF STRUCTURED LIPIDS WITH SPECIAL FUNCTIONAL PROPERTIES

Enzymatic acidolysis of rapeseed oil with capric acid was carried out to obtain structured lipids. The reaction was catalyzed by Lipozyme IM lipase from Rhizomucor miehei. The enzyme preparations contained 2.8 and 10% water. The reaction conditions were enzyme load of 8% (w/w total substrates), substrate mole ratio of 1:6 (rapeseed oil:capric acid), and reaction temperature of 65C. The results showed that triacylglycerols (TAG) after transesterification contained mainly oleic, linoleic and linolenic acids (about 90%) in the internal sn-2 position, whereas capric acid was mostly in the external sn-1,3 positions (approximately 40%). The quantity of water in the reaction medium had a significant influence on the yield and quality of the TAG fraction.     

The proteolytic activity of the crude enzyme extracts of Baltic cod (Gadus morhua) alimentary tract

The crude enzyme extract from Baltic cod alimentary tract had maximum activity of aspartic proteinases towards haemoglobin at pH 2.0 and 3.4, and of serine proteinases with casein as the substrate at pH 8.3 and 10.4. With bovine myofibrils as the substrate the proteolysis at pH 5.0-8.0 was maximum at the lowest and highest pH values. the optimum temperature for the proteolytic activity at pH 3.4 and 10.4 was 30–45°C and at pH 8.3 it was 40–50°C. Heating the crude extract for 10 min at pH 3.4,8.3, and 10.4 in the absence of the substrate had no effect on the activity of the acid and alkaline proteinases up to about 35–40°C. the stability at higher temperature decreased gradually and total inactivation occurred at 55–60°C. In the pH range 5.5–7.5 the proteolytic activity against bovine myofibrils was low at 0°C but brought about significant loss of myosin heavy chain at 20°C.     

On a two-level identification scheme of large-scale systems for open-loop steady-state optimization

In this paper an attempt is made to combine the problems of the control and modelling of large-scale systems. Starting from the idea of the model-based (open-loop) solution of the two-layer steady-state optimization problem for the noiseless large-scale system, or one corrupted by slow-varying disturbances, an appropriate two-level identification scheme is derived and discussed. The problems connected with its numerical realization are also stated. The considerations are confined to systems with the cascade structure—typical of most production processes—and to the case when the observations of system input/output signals, from which the system model is determined, are noise-free.