Metabolic Activity and Behavior of Lactobacillus Casei During Fermentation and Microencapsulation

Abstract

The metabolic activity and behavior of Lactobacillus casei were investigated during lactic fermentation and after microencapsulation. L.casei metabolic activity in vitro was investigated by HPLC and Infrared spectrometry (FTIR). Following the fermentation during 78 h, we identified lactic acid (retention time at 4.59 min) and its synthesis to begin after 3h and increasing gradually, up to a productivity of 6.89 mg mL-1 after 78 h. We noticed a high activity in the first 6 hours, and the media was totally consumed before 12 hours. By FT-IR fingerprint during fermentation we identified changes of the spectra pattern, specific increasing peaks of lactic acid (1127 cm-1) during fermentation (from 3 to 78 h) and other specific absorption peaks at 1420 cm-1, 2845 and 2929 cm-1. 
 The comparative behavior of L.casei microencapsulated in different matrices, in simulated gastric and intestinal juice were also studied. L.casei was microencapsulated in sodium alginate (AG), chitosan (CH), alginate: guar gum (AG:GU) and alginate: xanthan gum (AG:XA). The microencapsulation effects on the changes in survival rate of bacteria, during exposure in simulated gastric and intestinal juice were studied. The survivability of the strains, were expressed as the destructive value (decimal reduction time). The alginate beads 2% prevented acid-induced reduction of the cell density in simulated gastric juice, resulting in significant (P