In vitro and in vivo digestibility of prebiotic galactooligosacharides synthesized by ß-galactosidase from Lactobacillus delbruecki subsp. bulgaricus CRL450.

BACKGROUND: The general assumption that prebiotics reach the colon without any alterations has been challenged. Some in vitro and in vivo studies have demonstrated that 'non-digestible' oligosaccharides are digested to different degrees depending on their structural composition. In the present study, we compared different methods aiming to assess the digestibility of oligosaccharides synthesized by ß-galactosidase (ß-gal) of Lactobacillus delbruecki subsp. bulgaricus CRL450 (CRL450-ß-gal) from lactose, lactulose and lactitol. RESULTS: In the simulated gastrointestinal fluid method, no changes were observed. However, the oligosaccharides synthesized by CRL450-ß-gal were partially hydrolyzed in vitro, depending on their structure and composition, with rat small intestinal extract (RSIE) and small intestinal brush-border membrane vesicles (BBMV) from pig. Digestion of some oligosaccharides increased when mixtures were fed to C57BL/6 mice used as in vivo model; however, lactulose-oligosaccharides were the most resistant to the physiological conditions of mice. In general ß (1→6) linked products showed higher resistance compared to ß (1→3) oligosaccharides. CONCLUSION: In vitro digestion methods, without disaccharidases, may underestimate the importance of carbohydrates hydrolysis in the small intestine. Although BVMM and RSIE digestion assays are appropriate in vitro methods for these studies, in vivo studies remain the most reliable for understanding what actually happens in the digestion of oligosaccharides. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Fermentation of chickpea flour with selected lactic acid bacteria for improving its nutritional and functional properties.

AIMS: To improve the nutri-functional quality of chickpea flour by fermentation with selected lactic acid bacteria (LAB) to formulate functional legume-derived products. METHODS AND RESULTS: A Randomized Complete Block Design was carried out to assess the influence of experimental conditions (presence/absence of Lactiplantibacillus plantarum CRL2211 and/or Weissella paramesenteroides CRL2182, temperature, time and dough yield) on LAB population, acidification, antinutritional factors and total phenolic contents (TPCs) of chickpea flour. Fermentation with both strains for 24 h at 37°C produced an increase in LAB (up to 8.9 log CFU/g), acidity (final pH 4.06), TPC (525.00 mg GAE/100 g) and tannin and trypsin inhibitor removal (28.80 mg GAE/100 g and 1.60 mg/g, respectively) higher than the spontaneously fermented doughs. RAPD and Rep-PCR analysis revealed that fermentation was dominated by L. plantarum CRL2211. Molecular docking and dynamics simulations were useful to explain LAB enzyme behaviour during fermentation highlighting the chemical affinity of LAB tannases and proteinases to gallocatechin and trypsin inhibitors. Compared with other processing methods, fermentation was better than soaking, germination and cooking for increasing the techno-functional properties of chickpea flour. Fermented doughs were applied to the manufacture of crackers that contained 81% more TPC and 64% more antioxidant activity than controls. CONCLUSIONS: Fermentation for 24 h at 37°C with selected autochthonous LAB was the best method for improving the quality of chickpea flour and derived crackers type cookies. SIGNIFICANCE AND IMPACT OF STUDY: Chickpea is suitable for the development of novel functional foods. Fermentation with selected LAB would improve the final product quality and bioactivity. The combination of experimental and simulation approaches can lead to a better understanding of the fermentation processes to enhance the properties of a food matrix.

Prebiotic galactooligosaccharides production from lactose and lactulose by Lactobacillus delbrueckii subsp. bulgaricus CRL450.

Galactooligosaccharides (GOS) are useful dietary ingredients recognized worldwide as prebiotics. In the present study, we evaluated the ß-galactosidase (ß-gal) activity of a panel of lactic acid bacteria (LAB) in order to select strains for the synthesis of oligosaccharides from lactose (GOS) and lactulose (OsLu) with a potential prebiotic effect. Fifteen strains out of 20 were able to grow on lactose and showed ß-gal activities between 0.03 and 2.06 U mg-1, whereas eleven were able to synthesize GOS. Lactobacillus delbrueckii subsp. bulgaricus CRL450, the strain with the highest ß-gal activity, synthesized a maximum of 41.3% GOS and 21.0% OsLu from lactose and lactulose, respectively, with ß-(1 → 6) and secondary ß-(1 → 3) linkages. When these compounds were tested without purifying, as carbon sources for the development of recognized probiotics and the producer strain, high growth was observed compared to non-prebiotic sugars like glucose and lactose. When the purified oligosaccharides were tested, the bacterial growth decreased, but the microorganisms displayed metabolic activity evidenced by the consumption of carbohydrates and the production of lactic acid. Additionally, the purified oligosaccharides demonstrated a bifidogenic effect. The obtained results support the potential of L. delbrueckii subsp. bulgaricus CRL450 for the production of the prebiotics GOS and OsLu and encourage the optimization of their synthesis for the design of new functional food ingredients.

Synthesis of prebiotic galactooligosaccharides from lactose and lactulose by dairy propionibacteria.

The potential of probiotic bacteria to produce prebiotic oligosaccharides by transgalactosylation has been minimally studied. In this work, we screened the ß-galactosidase (ß-gal) activity of dairy propionibacteria (PAB) isolated from Argentinean foods to select strains for the synthesis of oligosaccharides from lactose (GOS) and lactulose (OsLu). PAB, when grown in a medium with lactose as a carbon source, were disrupted, and the cell-free extracts were assayed for ß-gal activity. Nine strains grew on lactose and showed ß-gal activities from 0.27 to 2.60 U mL-1. Propionibacterium acidipropionici LET 120, the strain with the highest activity, was able to synthesize, using 30% lactose and lactulose at pH 6.5 and 45 °C, 26.8% of LET 120-GOS and 26.1% of LET 120-OsLu after 24 h. When they were tested as carbon sources for growth, P. acidipropionici LET 120 attained higher biomasses, µmax and ß-gal activities at the expense of Aspergillus oryzae-OsLu, Vivinal®-GOS and lactulose compared to lactose or glucose. In addition, LET 120-GOS and LET 120-OsLu synthesized by PAB were prebiotic for some probiotic strains. For the first time, our results show the production of GOS and OsLu by dairy PAB, and these results encourage further studies on the optimization of the synthesis and structure characterization of the obtained oligosaccharides.