Effect of leavening agent on Maillard reaction and the bifidogenic effect of traditional French bread.

The study aimed to evaluate the effect of using sourdough or yeast as a leavening agent for French bread making on the Maillard reaction and the bifidogenic effect. Sugars, proteins, and free asparagine were quantified in bread dough before and after fermentation. The levels of the Maillard reaction precursors were very different depending on the leavening agent used, which affected the Maillard reaction during baking. Strecker degradation was favored in the crust of sourdough bread (SB), generating about 7 times more aldehydes than in the crust of yeast bread (YB), thus improving the sensory quality of the bread. In the YB crust, the melanoidization pathway was predominant. The bifidogenic effect of crust and crumb from both breads was evaluated through the in vitro growth of Bifidobacterium adolescentis. SB showed a higher bifidogenic effect, probably due to its composition more favorable for bacteria growth.

Bacteriological and geochemical features of the groundwater resources: Kettara abandoned mine (Morocco).

Waste water of the Kettara village, as well as the abandoned tailings, constitute a potential environmental issue with direct consequences on air, soil, water resources qualities and, on human health. In this paper, experimental investigations examine the environmental impact which is induced by the wastewater, mine tailings and the lithological factors of rocks. This multidisciplinary research allows to i) understand the transfer of the Metallic Trace Elements (selenium, arsenic, nickel and zinc) and sulfate ions in the fractured shales media, ii) to assess the water potability by using the microbiological analysis. The microbiological results reveal the domestic impact by the presence of several kinds of bacteria in the groundwater resources: E. coli, Fecal coliforms, Total coliforms, Enterococci, Mesophilic Aerobic Flora, Sulphite-reducing bacteria and Salmonella. Selenium, arsenic and the bacteriological contamination of the groundwater could be explained by five kinds of factors: i) the geological formations and the nature of the hydrogeological system (unconfined layer), ii) the groundwater flow, the hydraulic relation between the hydrogeological wells and, the fractures network in the shale aquifer. The piezometric map allows to highlight the groundwater flow from the North-East to North-West and to the South-West, the drainage axis towards the P21 well and the presence of the dividing axis in the contaminated zone by the arsenic, iii) the absence of the unhealthy habitats with permeable traditional septic tanks in the village; iv) the transfer of the spreading animal excrements from the soil to groundwater and, v) the migration of the wastewater towards downstream of the groundwater flow. The presence of the reed beds could explain the reduction of bacteria in the hydrogeological wells of the study area.

Effects of Maillard Reaction Products on Sensory and Nutritional Qualities of the Traditional French Baguette.

The goals of this study were to evaluate the effect of baking time on the Maillard reaction products (MRPs) generated in the crust of the traditional French baguette and to estimate their impact on its sensory characteristics, its acrylamide content, and its bifidogenic effect. Melanoidins, volatile compounds, and acrylamide were evaluated in the crust of traditional French baguettes baked between 12 and 22 min at 225 °C. The increase in melanoidins was positively correlated to the baking time, while volatile compounds only increased until 18 min. The acrylamide content was estimated to be below 18 µg/kg, which confirms the findings of EFSA that bread is not a main contributor to dietary acrylamide. A descriptive sensory analysis showed that the baking time positively affected the sensory quality of the crust. The consumer test revealed the same trend and the panelists favorably judged the well-baked baguettes based on a better crust flavor and crispness. The bifidogenic effect of the crust and the crumb from the baguettes baked 22 min was evaluated on the in vitro growth of Bifidobacterium adolescentis. The results demonstrated that the crumb and the crust had exactly the same bifidogenic impact, therefore not caused by melanoidins. PRACTICAL APPLICATION: The consumption of bread in France has decreased since 2007, although bread is considered by French people as "healthy" and essential to maintain a balanced diet. The current study evaluated the global qualities of the French baguette in order to highlight its high sensory quality and its beneficial effect by inducing a possible growth of bifidobacteria, even in well-baked baguettes. These findings allow the French bakery industry to develop an argument to promote its technical know-how and to help consumers choose healthier and tastier bread. Moreover, this study provided some recommendations of baking processes to maintain a high sensory quality of the French baguette and limit the formation of undesirable compounds, such as acrylamide, in the crust.

Repeated Oral Exposure to N ε-Carboxymethyllysine, a Maillard Reaction Product, Alleviates Gut Microbiota Dysbiosis in Colitic Mice.

BACKGROUND: Diet is suggested to participate in the etiology of inflammatory bowel diseases (IBD). Repeated exposure to Maillard reaction products (MRPs), molecules resulting from reduction reactions between amino acids and sugars during food heating, has been reported to be either potentially detrimental or beneficial to health. AIMS: The aim of this study is to determine the effect of repeated oral ingestion of N ε-carboxymethyllysine (CML), an advanced MRP, on the onset of two models of experimental IBD and on the gut microbiota composition of mice. METHODS: Mice received either saline (control) or N ε-carboxymethyllysine daily for 21 days. For the last week of treatment, each group was split into subgroups, receiving dextran sulfate sodium salt (DSS) or trinitrobenzenesulfonic acid (TNBS) to induce colitis. Intensity of inflammation was quantified, and cecal microbiota characterized by bacterial 16S ribosomal RNA (rRNA) amplicon sequencing. RESULTS: Daily oral administration of N ε-carboxymethyllysine did not induce intestinal inflammation and had limited impact on gut microbiota composition (Bacteroidaceae increase, Lachnospiraceae decrease). DSS and TNBS administration resulted in expected moderate experimental colitis with a shift of Bacteroidetes/Firmicutes ratio and a significant Proteobacteria increase but with distinct profiles: different Proteobacteria taxa for DSS, but mainly Enterobacteriaceae for TNBS. While N ε-carboxymethyllysine exposure failed to prevent the inflammatory response, it allowed maintenance of healthy gut microbiota profiles in mice treated with DSS (but not TNBS). CONCLUSIONS: Repeated oral exposure to CML limits dysbiosis in experimental colitis. IBD patients may modulate their microbiota profile by regulating the level and type of dietary MRP consumption.

Insights into bread melanoidins: fate in the upper digestive tract and impact on the gut microbiota using in vitro systems.

Bread melanoidins are heterogeneous, nitrogen-containing, brown macromolecules generated during the last stages of the Maillard reaction in bread. The aim of this study was to investigate the impact and fate of these bread melanoidins in the human gastrointestinal tract using in vitro systems. Batch systems as well as the TNO gastrointestinal tract were used for studying the digestion of various bread samples. These samples included bread crumb, bread crust and two bread-crust-simulating models: a fiber-free model (gluten, starch and glucose heated together) and its control, free of Maillard reaction products (gluten heated separately than starch and glucose). Furthermore, the impact of these two bread-crust-simulating models on the gut microbiota was assessed using a static anaerobic batch system. Bread melanoidins from bread crust and its model were shown to be partially digested by amylases and proteases, suggesting that these melanoidins have peptidic as well as glycosidic bonds in their skeleton. The impact of bread melanoidins from the bread-crust-simulating models and their digestion products on the gut microbiota revealed an individual-dependent response for most flora except for enterobacteria. This flora decreased by -22%, -48% & -100% depending on the individual. Thus, bread melanoidins seem to exert an anti-inflammatory effect by inhibiting enterobacteria.

Microorganisms and Maillard reaction products: a review of the literature and recent findings.

Research on the impact of Maillard reaction products (MRPs) on microorganisms has been reported in the literature for the last 60 years. In the current study, the impact of an MRP-rich medium on the growth of three strains of Escherichia coli was measured by comparing two classic methods for studying the growth of bacteria (plate counting and optical density at 600 nm) and by tracing MRP utilisation. Early stage and advanced MRPs in the culture media were assessed by quantifying furosine and N (ε) -carboxymethyllysine (CML) levels, respectively, using chromatographic methods. These measures were performed prior to and during bacterial growth to estimate the potential use of these MRPs by Escherichia coli CIP 54.8. Glucose and lysine, the two MRP precursors used in the MRP-rich medium, were also quantified by chromatographic means. Compared to control media, increased lag phases and decreased growth rates were observed in the MRP-rich medium for two out of the three Escherichia coli strains tested. In contrast, one strain isolated from the faeces of a piglet fed on a MRP-rich diet was not influenced by the presence of MRPs in the medium. Overall, CML as well as the products obtained by the thermal degradation of glucose and lysine, regardless of the Maillard reaction, did not affect the growth of the three strains tested. In addition, no degradation of fructoselysine or CML was found in the presence of Escherichia coli CIP 54.8.

A laboratory protocol for determining glucose and maximum ethanol production from wheat grain: application to a complete genetic set of near-isogenic waxy lines.

A laboratory protocol was developed to assess glucose and ethanol yields from wheat. The impact of the analyzed wholemeal flour quantity and the saccharification on the amount of released glucose was estimated. The whole process including the analytical methods (glucose and ethanol) was repeatable and reproducible. This protocol was used to assess the glucose and ethanol yields of six varieties and of a complete set of hexaploid near-isogenic waxy lines of cv. Trémie grown in three locations. As compared to the normal line of Trémie, double null (AnBnD) and triple null (nAnBnD) isogenic lines showed a low Hagberg falling number (218, 65, and 63 s, respectively), a higher grain protein content (10.7, 11.5, and 12.1% DM, respectively), a lower glucose yield (728, 703, and 707 kg/t, respectively), and a lower ethanol yield (463, 453, and 452 L/t, respectively). These values indicate a strong involvement of alleles encoded at Wx-B1 and Wx-D1 loci in grain composition.