Variation of CO₂ mole fraction in the lower free troposphere, in the boundary layer and at the surface

Eight years of occasional flask air sampling and 3 years of frequent in situ measurements of carbon dioxide (CO₂) vertical profiles on board of a small aircraft, over a tall tower greenhouse gases monitoring site in Hungary are used for the analysis of the variations of vertical profile of CO₂ mole fraction. Using the airborne vertical profiles and the measurements along the 115 m tall tower it is shown that the measurements at the top of the tower estimate the mean boundary layer CO₂ mole fraction during the mid-afternoon fairly well, with an underestimation of 0.27–0.85 μmol mol⁻¹ in summer, and an overestimation of 0.66–1.83 μmol mol⁻¹ in winter. The seasonal cycle of CO₂ mole fraction is damped with elevation. While the amplitude of the seasonal cycle is 28.5 μmol mol⁻¹ at 10 m above the ground, it is only 10.7 μmol mol⁻¹ in the layer of 2500–3000 m corresponding to the lower free atmosphere above the well-mixed boundary layer. The maximum mole fraction in the layer of 2500–3000 m can be observed around 25 March on average, two weeks ahead of that of the marine boundary layer reference (GLOBALVIEW). By contrast, close to the ground, the maximum CO₂ mole fraction is observed late December, early January. The specific seasonal behavior is attributed to the climatology of vertical mixing of the atmosphere in the Carpathian Basin

Effect of pH on Color and Texture of Food Products

[EN] Color and texture are important quality characteristics and major factors affecting sensory perception and consumer acceptance of foods. pH has an important effect on pigments (e.g., chlorophyll, carotenoids, anthocyanins, etc.) responsible for fruit color, vegetables and meat color. Also pH has a great impact on water-holding capacity and tenderness of muscle foods that are improved at acidic conditions below the typical pH of post-mortem. Moreover, during processing of food, the pH value affects many phenomena and processes such as protein properties as denaturizing, gelification, enzymatic activities, growth and mortality of microorganisms, germinating or inactivation of bacterial spores and chemical reactions such as the Maillard reaction. Thus, knowledge of pH effects and its control during processing is necessary to produce safe, high-quality and value-added products. 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