Influence of Osmotic Stress and Encapsulating Materials on the Stability of Autochthonous Lactobacillus plantarum after Spray Drying

Abstract

With the aim of producing a functional fish food, autochthonous Lactobacillus plantarum LPS 47, isolated from healthy Chilean salmon, was stabilized using spray drying. In order to increase the resistance of microorganisms to high temperatures, osmotic stress during fermentation and different protective agents were evaluated (lactic solids: skim milk and whey, maltodextrin, pectin, and arabic gum). We found that bacteria that were not exposed to osmotic stress during culture, and that were spray-dried in the presence of cheese whey (20% w/w) as a protective material, gave the best results in terms of viability, humidity, and stability during storage. Dehydrated material reached a viability of approximately 10⁹ CFU/g (colony-forming units per gram) and less than 5% humidity, values that were maintained over 10 weeks of storage at 4°C in a non-controlled atmosphere. Results show that it is possible to obtain a stable dehydrated probiotic product, with high concentration of microorganism, using spray drying and whey as a protective agent, without causing osmotic stress, by harvesting the biomass during the stationary phase.

Keywords:

• Encapsulation
• Osmotic stress
• Probiotics
• Spray drying

ACKNOWLEDGMENTS

The authors wish to thank Project INNOVA CHILE 05CT6PPT-13 and Project FONDECYT 1060919 for financial support.