Structural characterization of an exopolysaccharide produced by two strains of Lacticaseibacilluscasei.

Exopolysaccharides (EPSs) were isolated and purified from Lacticaseibacillus casei strains type V and RW-3703M grown under various fermentation conditions (carbon source, incubation temperature, and duration). Identical 1H NMR spectra were obtained in all cases. The molar mass determined by size-exclusion chromatography coupled with multi-angle light scattering was different for the two strains and in different culture media. The primary structure was elucidated using chemical and spectroscopic techniques. Monosaccharide and absolute configuration analyses gave the following composition: d-Glc, 1; d-Gal, 2; l-Rha, 2; d-GlcNAc, 1. Methylation analysis indicated the presence of 4-linked Glc, terminal and 6-linked Gal, terminal and 3-linked Rha, and 3,4,6-linked GlcNAc. On the basis of one- and two-dimensional 1H and 13C NMR data, the structure of the EPS was consistent with the following hexasaccharide repeating unit: {4)[Rhap(α1-3)][Galp(α1-6)]GlcpNAc(ß1-6)Galp(α1-3)Rhap(ß1-4)Glcp(ß1-}n. Complete 1H and 13C NMR assignments are reported.

Strategies to improve the survival of probiotic Lacticaseibacillus rhamnosus R0011 during the production and storage of granola bars.

The goal of this study was to evaluate the effectiveness of two approaches to protect the viability of probiotic cells during granola bar manufacturing and storage: microencapsulation (ME) and inclusion in chocolate chips. In the process used, hot honey (138 °C) was blended with cereal ingredients, resulting in an initial blend temperature of 52 °C. Chocolate chips carrying probiotics were added; however, when the blend was cooled to 42 °C. The viability of Lacticaseibacillus rhamnosus R0011 probiotic was assessed by flow cytometry (FC) and plating (CFU). There was an uneven distribution of inoculated probiotic bacteria throughout the cereal bars, resulting in variability in the CFU data. By providing total and viable counts, FC assessed the correct number of inoculated cells in the sample, which enabled the accurate calculation of survival levels. Spray coating with ME increased survival during manufacturing, but ME in alginate particles was detrimental. Including the cultures in chocolate improved the stability of the probiotics during storage at 25 °C, but only in the first 4 weeks. FC analyses showed that viability losses during bar manufacturing could be linked to damage to the cell membrane, but less so during storage.