EFFECTS OF ENCAPSULATION ON THE VIABILITY OF PROBIOTIC BACTERIA DURING THERMAL BEHAVIOR TESTS

To maintain the viability of probiotic microorganisms against adverse conditions during processing and storage, techniques such as encapsulation are studied. The aim of this study was to evaluate the viability of free and encapsulated probiotic microorganisms exposed to different temperatures. The lyophilized probiotic cultures used were Lactobacillus acidophilus, Lactobacillus rhamnosus and Bifidobacterium bifidum, activated in MRS broth and immediately encapsulated individually by the extrusion method from sodium alginate and calcium chloride. Free and encapsulated microorganisms were subjected to the following conditions: (1) room temperature (25±2ºC) until probiotic unfeasibility; (2) temperatures of 50, 75 and 100ºC for 15 minutes. At room temperature, probiotic viability analysis was performed at time zero and at every seven days, and in samples subjected to heating temperatures, the analysis was performed before and after 15minutes of permanence at the stipulated controlled temperatures in a water bath. Probiotic cells were analyzed by plating in MRS water and incubated in anaerobic for 72 hours/37°C. L. acidophilus and L. rhamnosus presented an initial count of 8 log CFU.g-1 and B. bifidum of 6 log CFU.g-1, free and encapsulated. After seven days stored at room temperature there was probiotic unfeasibility of free and encapsulated microorganisms. At 50ºC, free L. acidophilus reduced 5 log and L. rhamnosus 4 log, while free B. bifidum reduced 2 log. When encapsulated, L. acidophilus reduced 2 log and L. rhamnosus and B. Bifidum maintained the concentration, showing that the encapsulation provided protection to microorganisms at 50ºC. At 75ºC none of the free microorganisms survived, and the encapsulated ones had a viable count of 2 log CFU.g-1. At 100ºC there was disruption of the capsules and total unfeasibility of microorganisms. Tests show that the extrusion encapsulation method provides protection to microorganisms up to 75°C and does not protect when stored at room temperature.