Physiological and Technological Properties of Probiotic Lacticaseibacillus rhamnosus GG Encapsulated with Alginate-Chitosan Mixture and Its Incorporation in Whole Milk.

This study developed and evaluated chitosan-sodium alginate capsules containing the probiotic Lacticaseibacillus rhamnosus GG using extrusion and emulsification techniques. The encapsulated L. rhamnosus GG cells were also evaluated for technological and probiotic-related physiological functionalities, as well as when incorporated in UHT and powdered milk. Extrusion (86.01 ± 1.26%) and emulsification (74.43 ± 1.41%) encapsulation techniques showed high encapsulation efficiency and high survival rates of L. rhamnosus GG during 28 days of refrigeration and room temperature storage, especially emulsification capsules (> 81%). The encapsulated L. rhamnosus GG cells showed high survival rates during exposure to simulated gastrointestinal conditions (72.65 ± 1.09-114.15 ± 0.44%). L. rhamnosus GG encapsulated by extrusion and emulsification performed satisfactorily in probiotic-related physiological (pH and bile salts tolerance) and technological properties (positive proteolytic activity, diacetyl and exopolysaccharides production, high NaCl tolerance (> 91%), besides having high heat tolerance (> 76%)). L. rhamnosus GG in extrusion and emulsification capsules had high survival rates (> 89%) and did not significantly affect physicochemical parameters in Ultra-High Temperature (UHT) and powdered milk during storage. The results demonstrate that L. rhamnosus GG can be successfully encapsulated with alginate-chitosan as a protective material through extrusion and emulsification techniques. UHT and powdered milk could serve as appropriate delivery systems to increase the intake of this encapsulated probiotic by consumers.

Spreadable goat Ricotta cheese added with Lactobacillus acidophilus La-05: Can microencapsulation improve the probiotic survival and the quality parameters?

The impact of the addition of L. acidophilus La-05 (free cells, microencapsulated with alginate [30 g/L] or microencapsulated with alginate coated with chitosan [5 g/L]) on the quality parameters of spreadable goat Ricotta cheese during storage (7 °C/7 days) was evaluated. The addition of probiotic culture resulted in products with lower hardness, gumminess, and springiness, as well as higher cohesiveness and adhesiveness. Furthermore, it increased the yield, and altered the color (higher L*, a* and b* values). The microencapsulation of the probiotic cultures resulted in higher probiotic survival (>6 log CFU/mL in product and simulated gastrointestinal conditions), and improved technological (no moisture loss, lower proteolysis and organic acid content), texture (lower gumminess and adhesiveness), and volatile (compounds with floral and fruity notes and lower "goat" aroma) properties. Chitosan coating did not improve the effects. In conclusion, microencapsulation improved the probiotic survival and the quality parameters of spreadable goat Ricotta cheese.

Inhibitory effects of flavonoids on biofilm formation by Staphylococcus aureus that overexpresses efflux protein genes.

This study evaluated the efficacy of glycone (myricitrin, hesperidin and phloridzin) and aglycone flavonoids (myricetin, hesperetin and phloretin) in inhibiting biofilm formation by Staphylococcus aureus RN4220 and S. aureus SA1199B that overexpress the msrA and norA efflux protein genes, respectively. The minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC50 - defined as the lowest concentration that resulted in ≥50% inhibition of biofilm formation) of flavonoids were determined using microdilution in broth procedures. The flavonoids showed MIC >1024 µg/mL against S. aureus RN4220 and S. aureus SA1199B; however, these compounds at lower concentrations (1-256 µg/mL) showed inhibitory effects on biofilm formation by these strains. Aglycone flavonoids showed lower MBIC50 values than their respective glycone forms. The lowest MBIC50 values (1 and 4 µg/mL) were observed against S. aureus RN4220. Myricetin, hesperetin and phloretin exhibited biofilm formation inhibition >70% for S. aureus RN4220, and lower biofilm formation inhibition against S. aureus SA1199B. These results indicate that sub-MICs of the tested flavonoids inhibit biofilm formation by S. aureus strains that overexpress efflux protein genes. These effects are more strongly established by aglycone flavonoids.