Judul: Karakteristik Mikrokapsul Lactobacillus plantarum dan : Stabilitas dalam Selai Salak Selama Penyimpanan
Abstrak: Modern consumers expect their food to be healthy and to prevent illness. Therefore the demand of functional food including probiotic products growing significantly. Functional foods containing probiotic bacteria generally are dominated by milk-based foods. Recently, the incorporation of probiotic bacteria in various food products especially fruit-based products have been studied. Probiotic strains in this research had been isolated from saurkraut (Lb. plantarum BSL) and beef (Lb.plantarum 2C12). Many reports indicated that there were poor survival of probiotic bacteria in food products containing free probiotic cells. Providing probiotic living cells with a physical barrier such as microencapsulation to resist adversed effect of environmental conditions is therefore an approach currently receiving considerable interest. The objectives of the study were 1) to evaluate the effect of Lb. plantarum microencapsulation by emulsion technique toward the resistancy to heat, injured cell, low pH (2.0) and bile salt (0.5%) and its antimicrobial activity. 2) to determine the most suitable temperature for incorporation probiotic into snake fruit jam. 3) to study the viability of free and encapsulated Lb. plantarum in snake fruit jam, total yeast mold, pH changes and water activity during room storage. The first stage of this study was microencapsulation of probiotics by emulsion method with sodium alginate as encapsulanting material. Characterization of the encapsulated probiotic were conducted including resistance to heat, injured cell, low pH and bile salt resistance, antimicrobial activity againts E. coli ATCC 25922, Salmonella typhii ATCC 14038, S. aureus ATCC 25923, S. cereviseae ATCC 9763 and Aspergillus niger. The second stage was incorporating the encapsulated probiotic into snake fruit jam. The most suitable temperature for incorporate based on the result of heat resistance.The last stage was evaluation of the probiotic viability in snake fruit jam during storage in room temperature for 4 weeks. The results showed that high survival number (11 log cfu g-1) of both Lb. plantarum strains were achieved after encapsulation. Heat resistance of the encapsulated strains at 50oC was better than their free cells, but the higher the temperature applied the lower the number of survivors would be. Heating at 70oC was more detrimental to all encapsulated probiotics with a decrease of more than 5 log cell numbers. Heating at 50o-70oC caused injury to all probiotics cells. Encapsulation probiotics also showed significantly higher survival (P<0.05) in bile salt (0.5%) and low pH (pH 2) treatments compared to their free cells. All encapsulated Lactobacillus strains could inhibit the growth of E. coli, Salmonella typhii and S. aureus as well as their free cells, but none of them could inhibit S. cereviseae and Aspergillus niger. Encapsulated probiotic bacteria in snake fruit jam showed good viability throughout the four weeks of storage, whereas the free probiotic lost their viability within two weeks. No changes of pH and water activity of the products were observed between free and encapsulated probiotic. The overall results suggested that microencapsulated probiotic prepared by emulsion method is suitable to be incorporated in snake fruit jam and provided good stability during 4 weeks of storage at room temperature.
Keyword: probiotics, Lb. plantarum, snake fruit jam, microencapsulation