Application of the dynamic gastrointestinal simulator (simgi (R)) to assess the impact of probiotic supplementation in the metabolism of grape polyphenols
FOOD RESEARCH INTERNATIONAL
Authors: Gil-Sanchez, Irene; Cueva, Carolina; Tamargo, Alba; Quintela, Jose C.; de la Fuente, Esther; Walker, Alan W.; Victoria Moreno-Arribas, M.; Bartolome, Begona
Abstract
In this paper, the Dynamic Gastrointestinal Simulator (simgi (R)) is used as a model to the study the metabolic activity of probiotics at the intestinal level, and in particular, to assess the impact of probiotic supplementation in the microbial metabolism of grape polyphenols. Two independent simulations using fecal samples from two healthy volunteers were carried out. Changes in microbiota composition and in metabolic activity were assessed by qPCR and 16S rRNA gene sequencing and by analyses of phenolic metabolites and ammonium ions (NH4+). The strain Lactobacillus plantarum CLC 17 was successfully implanted in the colon compartments of the simgi (R) after daily feeding of 2 x 10(10) CFU/day for 7 days. Overall, no changes in bacterial diversity were observed after probiotic implantation. In comparison to the digestion of the grape polyphenols on their own, the inclusion of L. plantarum CLC 17 in the simgi (R) colon compartments led to a greater formation of phenolic metabolites such as benzoic acids, probably by the breakdown of high-molecular-weight procyanidin polymers. These results provide evidence that the probiotic strain Lactobacillus plantarum CLC 17 may improve the metabolism of dietary polyphenols when used as a food ingredient.
Synergy of red mud oxygen carrier with MgO and NiO for enhanced chemical-looping combustion
ENERGY
Authors: Lin, Shen; Gu, Zhenhua; Zhu, Xing; Wei, Yonggang; Long, Yanhui; Yang, Kun; He, Fang; Wang, Hua; Li, Kongzhai
Abstract
Low-cost oxygen carriers prepared by natural ores or solid wastes have been attracted much attention for large-scale application in chemical looping combustion (CLC) technology. However, these oxygen carriers usually exhibit low activity and poor stability because of their unsatisfied microstructure and/or components. In this study, red mud as oxygen carrier was modified by active (NiO or MnOx) and inert oxides (MgO, Al2O3 or ZrO2) to optimize its structure and composition for CLC of methane. The synergy among different components in the oxygen carriers for methane oxidation was discussed in detail. The results showed that the effect of MnOx on the reducibility of red mud was relatively weak, while the presence of a suitable amount of NiO significantly promoted the reactivity for methane complete oxidation. Addition of 15 wt% NiO could increase the average CH4 conversion and CO2 selectivity from 53% to 65%-75% and 99%, respectively, which is beneficial for the following capture of CO2 after combustion. Moreover, the addition of MgO into the NiO-RM carrier could improve the stability of oxygen carrier for successive chemical looping process. The formation of NiFe2O4 and MgNiO2 in the oxygen carrier contributed to the enhanced reducibility, and the multiple interactions among Fe, Ni and Mg oxides promoted the overall performance of oxygen carriers. During the reaction with methane, Ni oxides were firstly reduced to metal Ni, which acted as a catalyst to activate methane, improving the oxidation rate of methane by oxygen carriers. (C) 2020 Elsevier Ltd. All rights reserved.