Bovine milk oligosaccharides as anti-adhesives against the respiratory tract pathogen Streptococcus pneumoniae

Natural antimicrobial oligosaccharides in the food industry

An increase in the number of antibiotic resistance genes burdens the environment and affects human health. Additionally, people have developed a cautious attitude toward chemical preservatives. This attitude has promoted the search for new natural antimicrobial substances. Oligosaccharides from various sources have been studied for their antimicrobial and prebiotic effects. Antimicrobial oligosaccharides have several advantages such as being produced from renewable resources and showing antimicrobial properties similar to those of chemical preservatives. Their excellent broad-spectrum antibacterial properties are primarily because of various synergistic effects, including destruction of pathogen cell wall. Additionally, the adhesion of harmful microorganisms and the role of harmful factors may be reduced by oligosaccharides. Some natural oligosaccharides were also shown to stimulate the growth probiotic organisms. Therefore, antimicrobial oligosaccharides have the potential to meet food processing industry requirements in the future. The latest progress in research on the antimicrobial activity of different oligosaccharides is demonstrated in this review. The possible mechanism of action of these antimicrobial oligosaccharides is summarized with respect to their direct and indirect effects. Finally, the extended applications of oligosaccharides from the food source industry to food processing are discussed.

Coupling an ion chromatography to high resolution mass spectrometry (IC-MS) for the discovery of potentially prebiotic oligosaccharides in Chardonnay grape marc

Oligosaccharides are carbohydrates made of three to twenty monosaccharide units linked through glycosidic bonds. Emerging research into the potential prebiotic activity of oligosaccharides is creating opportunities to use industrial byproducts as value-added products. Grape marc is a residue left after winemaking and has been shown to provide health benefits to humans. In this study, we analyzed the oligosaccharides in Chardonnay grape marc by utilizing a hyphenated platform in which an ion chromatography (IC) system is coupled to an Orbitrap mass spectrometer (MS). With this platform, we obtained a structural library including 32 oligosaccharides with unique compositions of monosaccharides and 61 oligosaccharide structures. Notably, the ion chromatographic separation provided resolution of charged isomers while maintaining separation capacity for small, neutral oligosaccharides. High-quality tandem MS also facilitated the identification of oligosaccharides with structural modifications including methylation and the presence of sugar alditols and hexuronic acids. The data acquired by the IC-MS system were also compared with previously published LC-MS data. We found that these two platforms are largely complementary and, in combination, provide a more comprehensive characterization of oligosaccharides than either platform achieves alone.

Comparison of the antipathogenic effect toward Staphylococcus aureus of N-linked and free oligosaccharides derived from human, bovine, and goat milk

N-linked oligosaccharides (N-glycans) derived from milk were recently found to be antipathogenic. This study compares the antimicrobial activity of N-linked glycans and free oligosaccharides from human, bovine, and goat milk against Staphylococcus aureus. Milk N-glycans showed a bactericidal/bacteriostatic effect on the pathogen when compared to free milk oligosaccharides, evidenced by the clear zone from the halo assay, with the order of human milk >goat milk >bovine milk. None of the free milk oligosaccharide samples were bactericidal/bacteriostatic, despite its positive results in growth curve and minimum inhibitory concentration (MIC) assays which are believed to be related to hyperosmosis. Both N-glycans and free milk oligosaccharides can reduce the adhesion of Staphylococcus aureus to Caco-2 cells, however, N-glycans worked significantly more effective than free milk oligosaccharides. Structural analysis of all free oligosaccharide and N-glycan samples showed the obvious interspecies differences, and the structure/function relationship of the respected N-glycans is of interest for future study. The significant bactericidal/bacteriostatic activity possessed by human, bovine, and goat milk N-linked glycans holds great potential as a novel substitute for antibiotics.

Effect of Roasting on Oligosaccharide Abundance in Arabica Coffee Beans

Emerging research into the bioactivities of indigestible carbohydrates is illuminating the potential of various foods and food streams to serve as novel sources of health-promoting compounds. Oligosaccharides (OS) are widely present in milks and some plants. Our previous research demonstrated the presence of OS in brewed coffee and spent coffee grounds. Armed with this new knowledge, the next step toward improving the utilization of these valuable components involved investigating the effect of roasting on the formation and abundance of coffee OS. In the present study, we used advanced mass spectrometry to analyze a variety of coffee samples and demonstrated that a great structural diversity and increased abundance of OS is associated with higher roasting intensity. The present investigation also evaluated methods for OS extraction and fractionation. A preparative-scale chromatographic method, based on activated carbon, was developed to isolate enough amounts of OS from coffee to enable future confirmation of prebiotic and other in vitro activities.