Robustness of Bifidobacterium longum LMG 13197 encapsulated in lyophilized Vegetal BM 297 ATO-inulin lipid-based synbiotic microparticles

Abstract

Consumers are currently concerned about improving their health, and therefore demand foods that are beneficial to overall health. This has caused the rising interest in probiotics, which are live microorganisms which when ingested in sufficient amounts, restore balance in the gastrointestinal tract and consequently improve health. Probiotic bacteria have been incorporated into various food products which are now referred to as functional foods, and represent about 65% of the world‟s food market. Probiotics are sensitive to various environmental factors such as oxygen, moisture, pH and temperature. It is of great importance that probiotics remain viable and alive throughout the stages of processing, storage in food products and during gastrointestinal transit in order for them to confer health benefits. The use of prebiotics and microencapsulation to protect and ensure viability of probiotics has been used in food industries. Challenges faced when using most microencapsulation techniques include the need for a food grade encapsulating material, stability of the probiotic cells during encapsulation processes and storage, the need to minimize negative effects they might have on the organoleptic properties of foods into which they are incorporated. The freeze drying technique, which is known to be suitable for the preservation of probiotic cells, avoids heat induced injuries to cells and also slows down detrimental chemical reactions, was used in the current study to prepare microparticles encapsulating probiotic bifidobacteria. Due to limited reports on the use of lipid based food grade encapsulating materials for the microencapsulation of probiotics, this study explored the use of such materials and developed a lipid based synbiotic material which is expected to protect and improve probiotic viability. A lipid based excipient Vegetal BM 297 ATO and various concentrations of the prebiotic inulin were used to prepare different formulations, followed by an investigation to determine which concentration of inulin resulted in better protection and survival of Bifidobacterium longum LMG 13197 during the freeze drying process. Bifidobacterium longum LMG 13197 was successfully encapsulated in Vegetal using freeze drying method. It was observed that the formulation prepared with 2% (w/v) inulin resulted in better protection of B. longum LMG 13197 during the encapsulation process. Characterization of the microparticles revealed that they contained high numbers of bacterial cells resulting from relatively high encapsulation efficiency. The presence of inulin resulted in microparticles with an acceptable size which is desirable for food applications. These results led to further investigation of the potential of Vegetal-inulin matrix to protect bifidobacteria in simulated gastrointestinal fluids and improve shelf life under different storage conditions. This study demonstrates that the Vegetal-inulin matrix protected B. longum LMG 13197 during transit in the simulated gastric fluid (SGF) and subsequently released the cells in the simulated intestinal fluid (SIF). In comparison with the unencapsulated cells, the number of cells released in SIF was higher, which suggests that the Vegetal-inulin matrix has the potential to release probiotics in the colon for health benefits to be exerted. The shelf life of encapsulated B. longum LMG 13197 powders stored in glass bottles was investigated under two different storage temperatures for 6 weeks. The study demonstrates that although there was a high loss of viable probiotic cells during storage at 25°C, Vegetal-inulin matrix improved survival of probiotics for 3 weeks as opposed to the unencapsulated cells. On the other hand, encapsulation with Vegetal did not offer improved survival of bacteria when compared to the unencapsulated cells at 4°C, but the addition of inulin offered better protection for up to 5 weeks. Therefore, better shelf life of Vegetal-inulin microparticles containing B. longum LMG 13197 can be achieved at 4°C than at 25°C.