Influence of antioxidant location on the protection of oil encapsulated in powder

Encapsulation of Poly Unsaturated Fatty Acids (PUFAs) in solid matrix, by providing a physical barrier, is used to prevent or delay their degradation; and the use of antioxidant is expected to enhance PUFAs oxidative stability. In liquid emulsions, the effectiveness of antioxidants is known to depend on their distribution between the oil and aqueous phase. In this study, the impact of the lipophilic or hydrophilic character of phenolic antioxidants on the oxidative stability of encapsulated PUFAs was investigated following the evolution of conjugated dienes and antioxidant residual content during accelerated ageing test (50\ub0C, 60% RH). Dry emulsions containing 10%wt stripped sunflower oil (60% PUFAs), 89.7%wt maltodextrin DE12 (wall material) and 0.3%wt Tween\uae20 (surfactant) were produced by spray drying. Some were enriched with alpha-tocopherol (lipophilic - 500 ppm in oil) or chlorogenic acid (hydrophilic, 1000 ppm in maltodextrin), two scavengers of lipid radicals implied in oxidation.Antioxidants improved the oxidative stability of encapsulated oil. With chlorogenic acid, oil oxidation occurred after a two days lag phase whilst for alpha-tocopherol, no lag phase was observed but the oxidation rate was smaller than in control and chlorogenic acid powders during the ten first days of ageing (Fig, 1a). The residual concentration of chlorogenic acid deceased rapidly during the first two days and then remained constant whilst the concentration of alphatocopherol decreased regularly ensuring oil protection until it has been totally consumed after ten days (Fig.1b). The better oil protection provided by alpha-tocopherol during the first ten days of storage was attributed to the different location of both antioxidants within the macro-domains of the dry emulsion. Alpha-tocopherol, in oil droplets, was directly in contact with the oil to protect whilst for chlorogenic acid, entrapped in the solid matrix, only the fraction in contact with the oil droplets brought protection and 60% of initial chlorogenic acid remained preserved in the matrix

Atmospheric chemistry and transport of reactive nitrogen in Europe

Nature of the problem • Observations of atmospheric reactive nitrogen (Nr) deposition are severely restricted in spatial extent and type. The chain of processes leading to atmospheric deposition emissions, atmospheric dispersion, chemical transformation and eventual loss from the atmosphere is extremely complex and therefore currently, observations can only address part of this chain. Approaches: • Modelling provides a way of estimating atmospheric transport and deposition of Nr at the European scale. A description of the different model types is provided. • Current deposition estimates from models are compared with observations from European air chemistry monitoring networks. • The main focus of the chapter is at the European scale; however, both local variability and and intercontinental Nr transfers are also addressed. Key findings/state of knowledge: • Atmospheric deposition is a major input of Nr for European terrestrial and freshwater ecosystems as well as coastal sea areas. • Models are key tools to integrate our understanding of atmospheric chemistry and transport, and are essential for estimating the spatial distribution of deposition, and to support the formulation of air pollution control strategies. • Our knowledge of the reliability of models for deposition estimates is, however, limited, since we have so few observational constraints on many key parameters. • Total Nr deposition estimates cannot be directly assessed because of a lack of measurements, especially of the Nr dry deposition component. Differences among European regional models can be significant, however, e.g. 30% in some areas, and substantially more than this for specific locations. Major uncertainties/challenges • There are very few measurements of many of the key compounds (e.g. gaseous HNO3 , coarse-nitrate, NH3 ), which are needed to enable comprehensive model evaluation. Data on all compounds should be available at the same site if the mass-balance of Nr is to be assessed, pointing to the need for integrated site measurements in air monitoring networks. • The main needs for oxidised Nr compounds are to evaluate how well the models capture the partitioning between gaseous HNO3 and either fine or coarse nitrate aerosol. For reduced Nr compounds, better estimates of NH3 emissions are needed, and how these are affected by meteorological factors as well as agricultural practices, coupled with an understanding of biosphere–atmosphere exchange. • Dry deposition of particles, sub-grid fluxes of NHx compounds, and effects of topography on wet deposition are especially difficult to parameterise properly. Recommendations • There is a significant need for studies to constrain uncertain model parameters. This includes measurements of both the gas and particle phases of Nr compounds, and of atmosphere–biosphere fluxes of Nr compounds over sensitive ecosystems. • A balanced programme of observations and models is needed and is critical to future understanding of atmospheric transport and deposition of Nr containing pollutants at local to global scales.JRC.DDG.H.2-Climate change and air qualit