EFFECT OF DIFFERENT FOOD STRESS CONDITIONS ON THE VIABILITY OF ENCAPSULATED Lactobacillus plantarum AND Lactobacillus casei ISOLATED FROM KLILA (AN ALGERIAN TRADITIONAL FERMENTED CHEESE)

Klila is one of a variety of Algerian traditional cheeses. The present work aimed to study the viability of two lactobacilli: Lactobacillus plantarum and Lactobacillus casei isolated from Klila and immobilized by extrusion in 2% sodium alginate under different stress conditions (different NaCl concentrations, sugar stress, different pH values and simulated gastrointestinal conditions) during storage at 4oC. Results showed that viability of encapsulated cells was enhanced at high salt concentration; at 9%, viability of free Lb. casei cells decreased by 9 Log CFU/ml 14 days, and by only 0.2 Log CFU/ml for encapsulated cells. Encapsulated Lb. plantarum resisted up to 28 days while viability of free cells decreased by 9 Log CFU/ml in the 7th day at 9%. pH 2 showed the lowest viability which is decreased as the time of storage increased. After 14 days of storage, Lb. casei free cells decreased by 9 Log CFU/ml, encapsulated ones by only 2.8 Log CFU/ml, Lb. plantarum free cells by 9 Log CFU/ml and by 2.6 Log CFU/ml for encapsulated cells. Exposure to simulated gastrointestinal conditions showed that Lb. casei resisted such conditions compared to non-encapsulated cells which was not the case with Lb. plantarum. Storage in a commercial strawberry beverage showed that free cells did not resist more than the7th day while coated cells resisted till the 14th day. We conclude that encapsulation enhance the viability of bacteria in harsh conditions.