Batch stripping of flavour active compounds from beer: Effect of dry matter and ethanol on equilibrium and mass transfer in a packed column
Ammari, Ali ; Schroën, Karin - \ 2019
Food and Bioproducts Processing 118 (2019). - ISSN 0960-3085 - p. 306 - 317.
Alcohol - CO - Equilibrium - Ester - Henry's law constant - Mass transfer coefficient
Physiochemical similarities of volatile compounds and their interactions with the beer matrix are the main challenging factors in selective separation of ethanol for the production of non-alcoholic beer and removal of excess (off-)flavours produced during fermentation, such as isoamyl acetate. In this paper, we are especially interested in the effect of beer dry matter, a complex mixture of carbohydrates and proteins, and of ethanol on flavour behaviour during treatment with a packed bed column using CO2 as a stripping agent. By analysing the gas phase at different dry matter concentrations, we observed that its’ presence is a facilitating factor for ethyl acetate and isoamyl acetate release, whereas isoamyl alcohol is retained in the liquid phase. These effects are a result of combined mass transfer effects and affinity for carbon dioxide, which are both affected by the presence of ethanol in the feed stream. Mass transfer analysis of isoamyl alcohol and ethanol revealed that the resistance is not controlled by their solubility in water but the affinity to CO2.
Horizontal and vertical diversity jointly shape food web stability against small and large perturbations
Zhao, Qinghua ; Brink, Paul J. Van den; Carpentier, Camille ; Wang, Yingying X.G. ; Rodríguez-Sánchez, Pablo ; Xu, Chi ; Vollbrecht, Silke ; Gillissen, Frits ; Vollebregt, Marlies ; Wang, Shaopeng ; Laender, Frederik De - \ 2019
Ecology Letters 22 (2019)7. - ISSN 1461-023X - p. 1152 - 1162.
Equilibrium - horizontal diversity - large perturbations - small perturbations - stability - vertical diversity
The biodiversity of food webs is composed of horizontal (i.e. within trophic levels) and vertical diversity (i.e. the number of trophic levels). Understanding their joint effect on stability is a key challenge. Theory mostly considers their individual effects and focuses on small perturbations near equilibrium in hypothetical food webs. Here, we study the joint effects of horizontal and vertical diversity on the stability of hypothetical (modelled) and empirical food webs. In modelled food webs, horizontal and vertical diversity increased and decreased stability, respectively, with a stronger positive effect of producer diversity on stability at higher consumer diversity. Experiments with an empirical plankton food web, where we manipulated horizontal and vertical diversity and measured stability from species interactions and from resilience against large perturbations, confirmed these predictions. Taken together, our findings highlight the need to conserve horizontal biodiversity at different trophic levels to ensure stability.
Hazardous Chemicals in Plastics in Marine Environments : International Pellet Watch
Yamashita, Rei ; Tanaka, Kosuke ; Yeo, Bee Geok ; Takada, Hideshige ; Franeker, Jan A. van; Dalton, Megan ; Dale, Eric - \ 2019
In: Hazardous Chemicals Associated with Plastics in the Marine Environment Springer Verlag (Handbook of Environmental Chemistry ) - ISBN 9783319955667 - p. 163 - 183.
Additives - Equilibrium - Open ocean - Pellets - Sorption
Marine plastic debris, including microplastics <5Â mm, contain additives as well as hydrophobic chemicals sorbed from surrounding seawater. A volunteer-based global monitoring programme entitled International Pellet Watch (IPW) is utilizing the sorptive nature of plastics, more specifically of beached polyethylene (PE) pellets, in order to measure persistent organic pollutants (POPs) throughout the world. Spatial patterns of polychlorinated biphenyls (PCBs) and organochlorine pesticides have been revealed. Original data of IPW show large piece-to-piece variability in PCB concentrations in pellets collected at each location. This is explained by the combination of slow sorption/desorption and large variabilities of speed and route of floating plastics. The sporadically high concentrations of POPs, both sorbed chemicals and hydrophobic additives, are frequently observed in pellets and the other microplastics in open ocean and remote islands. This poses a chemical threat to marine ecosystems in remote areas.
Ancient genetic bottleneck and Plio-Pleistocene climatic changes imprinted the phylobiogeography of European Black Pine populations
Naydenov, Krassimir D. ; Naydenov, Michel K. ; Alexandrov, Alexander ; Vasilevski, Kole ; Hinkov, Georgi ; Matevski, Vlado ; Nikolic, Biljana ; Goudiaby, Venceslas ; Riegert, Dave ; Paitaridou, Despina ; Christou, Andreas ; Goia, Irina ; Carcaillet, Christopher ; Escudero Alcantara, Adrian ; Ture, Cengiz ; Gulcu, Suleyman ; Gyuleva, Veselka ; Bojovic, Srdjan ; Peruzzi, Lorenzo ; Kamary, Salim ; Tsarev, Anatoly ; Bogunic, Faruk - \ 2017
European Journal of Forest Research 136 (2017)5-6. - ISSN 1612-4669 - p. 767 - 786.
Bottleneck - cpDNA - Equilibrium - Expansion - Historical effective population size - Migration - Pinus nigra - Plio-Pleistocene climatic fluctuations
The historical changes in European Black Pine population size across the whole natural distribution in Europe and Asia Minor were analyzed facing the Plio-Pleistocene climatic fluctuations. Thirteen chloroplast SSRs and SNPs markers have been studied under the assumptions of “neutral evolution.” Populations and meta-populations had different histories of migration routes, and they were strongly affected by complex patterns of isolation, fragmentation, speciation, expansion (1.88–4.28 Ma), purification selection (2.09–21.41 Ma) and bottleneck (1.85–21.76 Ma). A significant number of populations (min. 29–41%) were in equilibrium for very long periods. Generally, the bottleneck revealed by chloroplast DNA is weaker than the bottleneck revealed by nuclear DNA. The Ne immediately after the bottleneck reaches between 1820 and 3640 individuals. Generally, the historical effective population sizes shrink significantly for the Tertiary period from 10–15 up to 2.5 Ma in Western Europe (by 82%), followed by Asia Minor (69%) and the Balkan Peninsula (28%), likely resulting from important climatic changes. The rates and frequencies of stepwise westwards migration waves have been not sufficient to prevent isolation between the meta-populations and to suppress “sympatric speciation.” The migration was weak for the Pliocene, but was maximal for the Pleistocene, and finally silent for the present interglacial period, namely the Holocene.
A methodological framework to determine optimum durations for the construction of soil water characteristic curves using centrifugation
Vero, Sara E. ; Healy, Mark G. ; Henry, Tiernan ; Creamer, Rachel E. ; Ibrahim, Tristan G. ; Forrestal, Patrick J. ; Richards, Karl G. ; Fenton, Owen - \ 2016
Irish Journal of Agricultural and Food Research 55 (2016)2. - ISSN 0791-6833 - p. 91 - 99.
Centrifuge - Equilibrium - Soil water characteristic curve
During laboratory assessment of the soil water characteristic curve (SWCC), determining equilibrium at various pressures is challenging. This study establishes a methodological framework to identify appropriate experimental duration at each pressure step for the construction of SWCCs via centrifugation. Three common temporal approaches to equilibrium – 24-, 48- and 72-h – are examined, for a grassland and arable soil. The framework highlights the differences in equilibrium duration between the two soils. For both soils, the 24-h treatment significantly overestimated saturation. For the arable site, no significant difference was observed between the 48- and 72-h treatments. Hence, a 48-h treatment was sufficient to determine ‘effective equilibrium’. For the grassland site, the 48- and 72-h treatments differed significantly. This highlights that a more prolonged duration is necessary for some soils to conclusively determine that effective equilibrium has been reached. This framework can be applied to other soils to determine the optimum centrifuge durations for SWCC construction.