Probiotics have been identified as an important nutritional factor for enhancing the gastrointestinal (GI) health. In order to exert health benefits, probiotics must be viable and available at high concentration at the time of product consumption. Several factors have been claimed to be responsible for reducing the viability of probiotics, such as acidity of products, antimicrobial substances, oxygen, and competitiveness by other bacteria species. Several technologies are being applied to improve probiotic survival in the food matrix during processing and storage as well as their efficacy in the GI track. Microencapsulation has proven an effective vehicle to deliver bioactive compounds in foods, including probiotics, and has been reported to protect sensitive probiotic lactic acid bacteria from oxygen, freezing, acidic conditions, as well as during gastrointestinal transit. The purpose of this study was to improve the viability of probiotic bacteria by microencapsulation using complex coacervates of whey protein isolates (WPI) and gum arabic (GA). Strains of Lactobacillus paracasei subsp. paracasei (B1) and Lactobacillus paraplantarum (E6) isolated from traditional Greek dairy products were microencapsulated by complex coacervation of WPI (3%) and GA (3%). The viability of the microencapsulated strains was evaluated at different pH values, upon storage at 4oC and under simulated gastrointestinal conditions. The complexes offered protection to both strains, offering viability of more than 65 % at pH 2.0 for 3h (37 oC), compared with 20% of the free cell cultures. Furthermore, both encapsulated strains retained high viability in simulated gastric juice (>74%), while the free cells showed less than 18%. No significant losses were also noted for both encapsulated strains during storage at pH 4.0 at 4oC for 45 days (> 85% % vs. 65 % for the free cells). Overall, encapsulation of probiotic strains in WPI-GA coacervates largely improved the survival of lactic acid bacteria cells and this approach might be an effective means of delivery for probiotic cultures in the gastrointestinal tract.
Professor Costas G. Biliaderis biliader@agro.auth.gr
