In vitro fermentation properties of pectins and enzymatic-modified pectins obtained from different renewable bioresources

The suitability of artichoke and sunflower by-products as renewable sources of pectic compounds with prebiotic potential was evaluated by studying their ability to modulate the human faecal microbiota in vitro. Bacterial populations and short-chain fatty acid (SCFA) production were measured. Reduction of the molecular weight of artichoke pectin resulted in greater stimulation of the growth of Bifidobacterium, Lactobacillus and Bacteroides/Prevotella, whilst this effect was observed only in Bacteroides/Prevotella for sunflower samples. In contrast, the degree of methylation did not have any impact on fermentability properties or SCFA production, regardless of the origin of pectic compounds. Although further in vivo studies should be conducted, either pectin or enzymatically-modified pectin from sunflower and artichoke by-products might be considered as prebiotic candidates for human consumption showing similar ability to promote the in vitro growth of beneficial gut bacteria as compared to well-recognized prebiotics such as inulin or fructo-oligosaccharides

Study on the digestion of milk with prebiotic carbohydrates in a simulated gastrointestinal model

The behaviour of oligosaccharides from lactulose (OsLu) included with milk was examined during in vitro gastrointestinal digestion using the Infogest protocol as well as some small intestine rat extract. The digestion was compared with commercial prebiotics GOS and Duphalac®. Electrophoretic analysis demonstrated that the prebiotic carbohydrates did not modify the gastric digestion of dairy proteins. Similarly, no significant effect of gastrointestinal digestion was shown on the prebiotic studied. In contrast, under the intestinal conditions using a rat extract, the oligosaccharides present in OsLu samples were less digested (<15%) than in GOS (35%). Moreover, lactulose was more prone to digestion than their corresponding trisaccharides. These results demonstrate the limited digestion of OsLu and their availability to reach the large intestine as prebiotic

INFOGEST static in vitro simulation of gastrointestinal food digestion

peer-reviewedSupplementary information is available at http://dx.doi.org/10.1038/s41596-018-0119-1 or https://www.nature.com/articles/s41596-018-0119-1#Sec45.Developing a mechanistic understanding of the impact of food structure and composition on human health has increasingly involved simulating digestion in the upper gastrointestinal tract. These simulations have used a wide range of different conditions that often have very little physiological relevance, and this impedes the meaningful comparison of results. The standardized protocol presented here is based on an international consensus developed by the COST INFOGEST network. The method is designed to be used with standard laboratory equipment and requires limited experience to encourage a wide range of researchers to adopt it. It is a static digestion method that uses constant ratios of meal to digestive fluids and a constant pH for each step of digestion. This makes the method simple to use but not suitable for simulating digestion kinetics. Using this method, food samples are subjected to sequential oral, gastric and intestinal digestion while parameters such as electrolytes, enzymes, bile, dilution, pH and time of digestion are based on available physiological data. This amended and improved digestion method (INFOGEST 2.0) avoids challenges associated with the original method, such as the inclusion of the oral phase and the use of gastric lipase. The method can be used to assess the endpoints resulting from digestion of foods by analyzing the digestion products (e.g., peptides/amino acids, fatty acids, simple sugars) and evaluating the release of micronutrients from the food matrix. The whole protocol can be completed in ~7 d, including ~5 d required for the determination of enzyme activities.COST action FA1005 INFOGEST (http://www.cost-infogest.eu/ ) is acknowledged for providing funding for travel, meetings and conferences (2011-2015). The French National Institute for Agricultural Research (INRA, www.inra.fr) is acknowledged for their continuous support of the INFOGEST network by organising and co-funding the International Conference on Food Digestion and workgroup meeting

Enzymatic production and characterization of pectic oligosaccharides derived from citrus and apple pectins: A GC-MS study using random forests and association rule learning

Pectic oligosaccharides (POS) from citrus and apple pectin hydrolysis using ViscozymeL and Glucanex200G have been obtained. According to the results, maximum POS formation was achieved from citrus pectin after 30 min of hydrolysis with ViscozymeL, with a yield of 652 mg g–1 and average molecular mass (Mw) of 0.8–2.5 kDa, while with Glucanex200G, the yield was 518 mg g–1 and Mw was 0.8–7.1 kDa. Digalacturonic and trigalacturonic acids were identified among other low Mw compounds as di- and tri-POS. In addition, differences in GC-MS spectra of all oligosaccharides found in the hydrolysates were studied by employing random forests and other algorithms to identify structural differences between the obtained POS, and high prediction rates were shown for new samples. Chemical structures were proposed for some influential m/z ions, and 12 association rules that explain differences according to pectin and enzyme origin were built. This information could be used to establish structure–function relationships of POS.This work has been funded by MICINN of Spain, Projects AGL2014-53445-R and AGL2017-84614-C2-1-R. C.S. is thankful for his FPU Predoc contract from Spanish MECD (FPU14/03619).Peer reviewe

Disentangling regional and local tree diversity in the Amazon

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordWe analyzed the most extensive data set of tree inventory plots spread over the complete Amazon basin and Guiana shield. We aimed to separate the regional and local tree alpha‐diversity to investigate the drivers of diversity at the relevant scale. Our results are consistent with the partitioning of total tree alpha‐diversity into regional and local components, which are controlled by evolutionary‐ and ecological processes, respectively. Regional diversity is correlated with palaeo‐climatic stability (31%), and long‐term large‐scale ecosystem dynamics (14%), as represented by the age of the geological formation. Both mechanisms contribute to high diversity in the central to western Amazon. Actual rainfall seasonality is correlated with regional tree diversity to a certain extent (19%), but we argue that this is of little consequence for the evolutionary drivers of the regional species pool. Frequency of disturbance is the main process driving local diversity, although its explanatory power is relatively small (17%).The first author was supported by PAN‐AMAZONIA project, Inst. Internacional de Educação do Brasil (BECA program) and Conselho Nacional de Ciência e Tecnologia (CNPq – Brazil)