Analysis and mathematical modelling of the behaviour of Escherichia coli in the mascarpone cheese during cold storage

The aim of this work was to study the behaviour of E. coli in mascarpone cheese during storage at the temperatures ranging from 3 to 15 °C, as well as application of predictive microbiology to describe the experimental data. The Baranyi, Gompertz and logistic models were fitted at the stage of primary modelling. Although all applied primary models described the growth of micro‐organisms accurately, the most accurate goodness of fit was obtained for the Gompertz model and the growth rates generated by this model were used for secondary modelling. The polynomial model predicted accurately the influence of temperature on the growth rate of E. coli, reaching the adjusted coefficient of linear regression 0.99. Generated predictive model that describes the growth of E. coli in mascarpone cheese constitutes a valuable tool in assessing the microbiological stability of the food product with similar physicochemical properties.     

Validation of a UV Spectrophotometric Method for Determination of Proteolytic Activity of Enzymatic Detergents

Enzymatic detergents are widely used in health services. These products should be controlled to ensure their activity. In this paper, a UV spectrophotometric method for the determination of proteolytic activity in enzymatic detergents was validated. An artificial substrate (azocasein) was used to quantify the enzyme activity at 340 nm. The results showed that the method was satisfactory in respect to its specificity, linearity, precision, accuracy and robustness. This method fulfills both ICH’s and Brazilian criteria, demonstrating its suitability for routine analysis as well as its potential application for regulatory purposes.     

Phenotypic,genetic and technological characterization of Lactococcus garvieae strains isolated from a raw milk cheese

A series of Lactococcus garvieae strains isolated as the majority population of a Spanish traditional, starter-free cheese made from raw milk were phenotypically and genotypically characterised to address their biochemical potential, safety requirements, and technological properties. As expected, all L. garvieae cheese strains fermented lactose but grew slowly in UHT-treated milk. Enzymatic activities of L. garvieae were similar to those of Lactococcus lactis, although higher esterase and lipase activities were recorded for L. garvieae strains. Profiles of the volatile compounds produced from milk by L. garvieae and L. lactis strains were also comparable. L. garvieae strains did not produce haemolysin, gelatinase and the biogenic amines tyramine and histamine. Five L. garvieae stains showed tetracycline resistance encoded by a tet(M) gene. The use of L. garvieae strains as starter or adjunct cultures might be recommended for certain cheese types, provided that the safety of the strains has been demonstrated.     

Impacts of climate changes on crop physiology and food quality

Carbon emissions related to human activities have been significantly contributing to the elevation of atmospheric [CO₂] and temperature. More recently, carbon emissions have greatly accelerated, thus much stronger effects on crops are expected. Here, we revise literature data concerning the physiological effects of CO₂ enrichment and temperature rise on crop species. We discuss the main advantages and limitations of the most used CO₂-enrichment technologies, the Open-Top Chambers (OTCs) and the Free-Air Carbon Enrichment (FACE). Within the conditions expected for the next few years, the physiological responses of crops suggest that they will grow faster, with slight changes in development, such as flowering and fruiting, depending on the species. There is growing evidence suggesting that C₃ crops are likely to produce more harvestable products and that both C₃ and C₄ crops are likely to use less water with rising atmospheric [CO₂] in the absence of stressful conditions. However, the beneficial direct impact of elevated [CO₂] on crop yield can be offset by other effects of climate change, such as elevated temperatures and altered patterns of precipitation. Changes in food quality in a warmer, high-CO₂ world are to be expected, e.g., decreased protein and mineral nutrient concentrations, as well as altered lipid composition. We point out that studies related to changes in crop yield and food quality as a consequence of global climatic changes should be priority areas for further studies, particularly because they will be increasingly associated with food security.     

Evaluation of Current Condition and Lifespan of Drinking Water Pipelines

The condition of underground water pipelines was assessed, and a large amount of data for both the soil and the corresponding pipeline section were collected. Statistical techniques were employed first to establish the sampling design and later for the data analysis and obtaining a mathematical expression for pitting depth as a function of several experimental variables. The data were used to evaluate corrosivity, current condition and lifespan of the pipeline under study and present the results graphically in the form of maps. The approaches and techniques employed here provide a useful tool for structuring maintenance programs.     

Oil and fungal biomass dispersion in a stirred tank containing a simulated fermentation broth

The production of γ‐decalactone by the filamentous fungus Trichoderma harzianum involves four phases (oil–water–air–mycelium) and its dispersion is crucial during fermentation. Oil and biomass (when present) dispersion, as a function of the volumetric power drawn (P/V), was characterized, in two; three‐ and four‐phase systems agitated with Rushton turbines. Trichoderma harzianum mycelium was used as the solid phase in the four‐phase system. Two stages of the fermentation were simulated: the beginning (15% oil and 1.4 kgm^?3 of mycelium) and the end (2% oil and 10.6 kg m^?3 of mycelium). In the two‐phase system, the use of exhausted broth achieved higher oil dispersions at low P/V values as compared with distilled water. Aeration decreased the oil dispersion for the high‐oil system, but enhanced oil dispersion for the low‐oil system. Compared with the P/V used in the actual fermentation (0.2 kW m^?3), a high segregation of the system was observed for the high‐oil/low‐biomass system, due to the difficulty of mixing the thick oil–air emulsion present at the top of the tank. The system simulating the end of the fermentation reached almost complete homogeneity of oil and biomass, a phenomenon due to the high biomass/oil ratio and the biomass acting as an oil carrier. © 2001 Society of Chemical Industry     

Fluorescent core-sheath fibers by electrospinning of a phenyleneethynylene/poly(styrene-co-maleimide) blend

Ultrafine fluorescent fibers were prepared by electrospinning of a phenyleneethynylene oligomer mixed in DMF with a poly(styrene-co-maleimide) (PSM). The microscopic characterization by SEM reveals that the fibers are smooth and entangled one to the others forming a non-woven mat with an average diameter of 490 nm. By TEM, a core-sheath type structure is observed which derives from phase segregation between the PSM interacting with the oligomer and the excess of PSM that acts as matrix, as supported by XRD and DSC analysis. The membranes are fluorescent emitting at 420 nm, in the blue region, a high energy light, opening the possibility of their application in optoelectronic devices such as fluorescent sensors. Preliminary assays have been performed for the detection of sodium ions.     

Influence of water type and maturation time on the properties of kaolinite–saponite peloids

We studied the effects of maturation time and water type on the properties of peloids. The peloids were prepared artificially by mixing the same amount of solid phase of kaolin and bentonite (9:1, m:m) with hypersaline mineral water (sodium potassium chloride water) from a spring in La Malahá (Granada, Spain) and bidistilled water (oligometallic water). The liquid/solid ratio was 2:1, m:m, with periodic manual homogenization and maturation time of one to three months. The water content of the peloids was maintained constant during the entire period of maturation.The peloid properties considered were the composition of the liquid phase, the thermal behaviour, the amount of defects in the structure of the main minerals present in the solid phase (kaolinite and saponite) and the ultramicroscopic fabric of the material, determined by scanning electron microscopy (SEM) and image analysis (IA). To date, the latter aspect has been very little studied.The composition of the liquid phases changed with maturation time. Most of the parameters measured showed a tendency to increase with increasing maturation time, as a consequence of releasing ions from the clay minerals into the liquid phase. Thus, the bidistilled water became mineral water. The initial differences between the two waters employed in the mixture were maintained in the liquid phases.The investigation of the thermal behaviour of the peloid revealed that the decrease in temperature followed, with time, a fitted logarithmic curve where R² > 0.9. The maximum change occurred in the first stage, later cooling being slower. A statistic relationship was found between the cooling kinetic and pore size and the size of the particle aggregates measured by SEM-IA. The peloids cooled more rapidly with increasing maturation time, as in the case of saline water.Both the Hinckley index of kaolinite and Integral Breadth index of saponite changed with the maturation time of the peloid. At the end of the maturation process similar values were reached regardless of the water employed.The main effect of maturation time was the increase in the size of the particle aggregates, the formation of a fabric with a more reticular morphology, and the increase in the area occupied by the pores in the SEM micrographs.     

Exercise training-induced changes in sensitivity to endothelin-1 and aortic and cerebellum lipid profile in rats

The purpose of this work was to study whether exercise training induces changes in the lipid profile of rat aorta and nervous system and in the in vitro intrinsic responsiveness of these tissues to endothelin-1 (ET-1) treatment. The exercise program performed successfully produced the characteristic metabolic alterations of the trained state. Exercise training induced a large and significant increase in the levels of both aortic ethanolamine plasmalogens (PlasEtn) and glucosylceramides. In contrast, a decrease of aortic ceramide and cholesterol levels was evoked by exercise training. ET-1 increased PlasEtn content only in sedentary animals. An exercise-induced increase in cerebellum levels of ceramides and ceramide monohexosides was found. The cerebellum ceramide content was increased by FT-1 more noticeably in sedentary rats than in trained animals. In contrast, cerebral cortex was observed to be largely insensitive to both exercise training and ET-1 treatment. It was concluded that exercise training (i) induces changes in both vascular and cerebellar lipid profiles, the former being much more pronounced than the latter, and (ii) diminishes the aortic and cerebellar sensitivity to ET-1 action.