Effect of the carrier material, drying technology and dissolution media on the viability of Lactobacillus fermentum K73 during simulated gastrointestinal transit.

The goal of this study was to determine the effect of the carrier material, drying technology and dissolution media during the passage of L. fermentum K73 through a dynamic in vitro digestion system (IViDiS). The carrier materials were (i) culture medium with growing micro-organisms and (ii) culture medium with maltodextrin : sweet whey [0.6 : 0.4]. The carrier materials were dried by spray-drying and freeze-drying to obtain four types of powders. The dissolution media consisted of water and 1% fat milk. The powders were tested using an in vitro dynamic digestion system (IViDiS). The results showed that powders derived from culture medium had the highest protective effect on the viability of L. fermentum K73 in both dissolution media and that survival increased when the powders were tested in milk. The modified Gompertz model was used to model L. fermentum K73 behaviour during the digestion process. The model showed that cells entrapped in culture medium had the longest lag phase and the slowest inactivation rate when evaluated in milk.

Encapsulation of Lactobacillus fermentum K73 by Refractance Window drying.

The purpose of this work was to model the survival of the microorganism and the kinetics of drying during the encapsulation of Lactobacillus fermentum K73 by Refractance Window drying. A whey culture medium with and without addition of maltodextrin were used as encapsulation matrices. The microorganism with the encapsulation matrices was dried at three water temperatures (333, 343 and 353 K) until reaching balanced moisture. Microorganism survival and thin layer drying kinetics were studied by using mathematical models. Results showed that modified Gompertz model and Midilli model described the survival of the microorganism and the drying kinetics, respectively. The most favorable process conditions found with the mathematical modelling were a drying time of 2460 s, at a temperature of 353 K. At these conditions, a product with 9.1 Log CFU/g and a final humidity of 10% [wet basis] using the culture medium as encapsulation matrix was obtained. The result shows that Refractance Window can be applied to encapsulate the microorganism probiotic with a proper survival of the microorganism.

Multifunctional Role of the Whey Culture Medium in the Spray Drying Microencapsulation of Lactic Acid Bacteria.

This study aims to evaluate the multifunctional role of whey culture medium during the spray drying microencapsulation of Lactobacillus fermentum K73. Whey culture medium containing growing microorganisms served to hydrate different mixtures (gum arabic, maltodextrin and whey). We evaluated the use of these mixtures as carbon sources and their protective effects on simulated gastrointestinal conditions. The optimal mixture was spray-dried while varying the outlet temperature and atomizing pressure using a response surface design. These conditions served to evaluate microorganism survival, tolerance to gastrointestinal conditions in vitro, physicochemical properties, morphometric features and stability at 4, 25 and 37 °C. Lactobacillus fermentum K73 replicated in the carrier material. Bacterial change cycles were (-1.97±0.16) log CFU/g after the drying process and (-0.61±0.08) and (-0.23±0.00) log CFU/g after exposure of the capsules to simulated gastric pH and bile salt content, respectively. The physicochemical properties and morphometric features were within the normal ranges for a powder product. The powder was stable at a storage temperature of 4 °C. The spray drying of the whey culture medium with growing microorganisms using the optimized drying conditions was successful. This study demonstrates the use of whey culture medium as a component of carrier material or as the carrier material itself, as well as its protective effects during drying, under simulated gastrointestinal conditions, and at varied storage temperatures.