Sourdough bread enriched with exopolysaccharides and gazpacho by-products modulates in vitro the microbiota dysbiosis.

Sourdough bread enriched with soluble fiber (by in-situ exopolysaccharides production) and insoluble fiber (by gazpacho by-products addition) showed prebiotic effects an in vitro dynamic colonic fermentation performance with obese volunteer's microbiota. Bifidobacterium population was maintained whereas Lactobacillus increased throughout the colonic sections. Conversely, Enterobacteriaceae and Clostridium groups clearly decreased. Specific bacteria associated with beneficial effects increased in the ascending colon (Lactobacillus fermentum, Lactobacillus paracasei, Bifidobacterium longum and Bifidobacterium adolescentis) whereas Eubacterium eligens, Alistipes senegalensis, Prevotella copri and Eubacterium desmolans increased in the transversal and descending colon. Additionally, Blautia faecis and Ruminococcus albus increased in the transversal colon, and Bifidobacterium longum, Roseburia faecis and Victivallis vadensis in the descending colon. Bifidobacterium and Lactobacillus fermented the in-situ exopolysaccharides and released pectins from gazpacho by-products, as well as cellulosic degraded bacteria. This increased the short and medium chain fatty acids. Acetic acid, as well as butyric acid, increased throughout the colonic tract, which showed greater increases only in the transversal and descending colonic segments. Conversely, propionic acid was slightly affected by the colonic fermentation. These results show that sourdough bread is a useful food matrix for the enrichment of vegetable by-products (or other fibers) in order to formulate products with microbiota modulatory capacities.

Combination of SPE and fluorescent detection of AQC-derivatives for the determination at sub-mg/L levels of biogenic amines in dairy products.

Biogenic amines (BAs) are compounds generated by decarboxylation of their amino acid precursors. Their intake, even at low concentrations, can lead to several types of health problems in sensitive individuals. As they can be easily formed in fermented dairy products, their quantitative determination is very relevant. In the present paper, a method for the quantitative determination of four biogenic amines in different dairy products has been developed, validated and applied to 37 samples of milk, 23 of yogurt, and 14 of kefir. Amines were selectively extracted using solid phase extraction, subsequently derivatizatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate and further determined by High Performance Liquid Chromatography with fluorescence detection. The method's sensitivity was highly satisfactory, with limits of detection lower than 0.2 mg/L. Optimal linearity and repeatability were also achieved. BAs were not detected in most of the milk samples, but they were found frequently at high levels in yogurt and kefir samples, reaching values of up to 79 mg/kg total BAs in kefir samples. Levels measured should not be a cause for concern for the population at large, but should be known by BAs-sensitive individuals.

Potential of histamine-degrading microorganisms and diamine oxidase (DAO) for the reduction of histamine accumulation along the cheese ripening process.

Lentilactobacillus parabuchneri is the main bacteria responsible for the accumulation of histamine in cheese. The goal of this study was to assess the efficiency of potential histamine-degrading microbial strains or, alternatively, the action of the diamine oxidase (DAO) enzyme in the reduction of histamine accumulation along the ripening process in cheese. A total of 8 cheese variants of cow milk cheese were manufactured, all of them containing L. parabuchneri Deutsche Sammlung von Mikroorganismen 5987 (except for the negative control cheese variant) along with histamine-degrading strains (Lacticaseibacillus casei 4a and 18b; Lactobacillus delbrueckiisubsp. bulgaricus Colección Española de Cultivos Tipo (CECT) 4005 and Streptococcus salivariussubsp.thermophilus CECT 7207; two commercial yogurt starter cultures; or Debaryomyces hansenii), or DAO enzyme, tested in each cheese variant. Histamine was quantified along 100 days of cheese ripening. All the degrading measures tested significantly reduced the concentration of histamine. The highest degree of degradation was observed in the cheese variant containing D. hansenii, where the histamine content decreased up to 45.32 %. Cheese variants with L. casei, or L. bulgaricus and S. thermophilus strains, also decreased in terms of histamine content by 43.05 % and 42.31 %, respectively. No significant physicochemical changes (weight, pH, water activity, color, or texture) were observed as a consequence of the addition of potential histamine-degrading adjunct cultures or DAO in cheeses. However, the addition of histamine-degrading microorganisms was associated with a particular, not unpleasant aroma. Altogether, these results suggest that the use of certain histamine-degrading microorganisms could be proposed as a suitable measure in order to decrease the amount of histamine accumulated in cheeses.

Consumption of Sourdough Breads Improves Postprandial Glucose Response and Produces Sourdough-Specific Effects on Biochemical and Inflammatory Parameters and Mineral Absorption.

To evaluate responses to different sourdough breads, six groups of rats were fed a conventional refined wheat bread with no sourdough content (C_WhB); a leavened spelt bread baked with Rebola sourdough (Re_SpB); a durum wheat bread with Rebola sourdough (Re_DuB); or a multigrain bread leavened with Rebola (Re_MGB), Carla (Ca_MGB), or San Francisco sourdough (SF_MGB). Compared to C_WhB-fed rats, Re_SpB-, Re_DuB-, and Re_MGB-fed animals showed lower postprandial blood glucose levels, whereas SF_MGB-fed rats displayed a decreased postprandial blood insulin response and glucose and insulin products. The 3 week intake of Ca_MGB decreased blood triacylglycerols and the relative apparent absorption (RAA) of Fe2+, Cu2+, and Zn2+, whereas Re_MGB-fed animals showed lower serum levels of the MCP-1 inflammatory marker and decreased the Fe RAA. The 3 week consumption of the multigrain bread produced sourdough-specific effects. Thus, Re_MGB-fed animals displayed higher insulin concentrations than Ca_MGB- and SF_MGB-fed rats and decreased blood MCP-1 levels compared to those of Ca_MGB-fed animals. In addition, Ca_MGB-fed rats showed lower serum triacylglycerol concentrations than those of Re_MGB- and SF_MGB-fed animals, whereas SF_MGB-fed rats displayed higher RAA values of Ca2+, Cu2+, Fe2+, Mg2+, and Zn2+ than their Re_MGB and Ca_MGB counterparts. These sourdough-specific effects could be related to changes in the contents of sugars and organic acids, acidity, microbial composition, and proteolytic activity among sourdoughs. Hence, the consumption of sourdough breads improved postprandial blood glucose and insulin responses and produced sourdough-specific effects on RAA and serum insulin and triacylglycerol and MCP-1 levels in rats, showing that SF_MGB has the most promising beneficial effects.