Vegetal BM 297 ATO as a potential food grade coating material for microencapsulation of Bifidobacterium lactis Bb12 probiotic strain under supercritical conditions

Abstract

The use of probiotics administered either in a direct clinical sense or indirectly as a food additive has grown greatly in recent years due to the new 'healthy living' trend. The global market for probiotics was worth R186.2 billion in 2013, showing a growth of 4.3% compounded per annum over a period of five years. Probiotics are however sensitive to different environmental factors such as light, moisture and oxidation in addition to the stresses encountered during processing. The shelf of probiotics in foodstuffs and pharmaceuticals are limited, which lead to increased costs to the manufacturer in having to incorporate enough cultures to account for losses, or a decreased benefit to the consumer in not receiving the required amount of cells needed for health benefits to be actualized. Microencapsulation is a technique used to protect probiotic cells against harsh conditions encountered both in the environment during storage and transport, and in the human body after consumption. This leads to higher numbers of viable probiotic cells being available to the consumer after consumption and decreased costs to the manufacturer as less cells need to be added. Current microencapsulation techniques are plagued with problems such as the inability to be produced at an industrial scale, the use of toxic solvents which kill the probiotic cells and contribute to pollution and the need for FDA approval of the pharmaceutical grade excipients they use. A novel encapsulation technique using the Particles from a Gas Saturated Solution (PGSS) system has been developed by the Council for Scientific and Industrial Research (CSIR), which does not require organic solvents and uses carbon dioxide in a supercritical state to create microcapsules. There is very limited knowledge on the use of lipid based food grade excipients for use in probiotic microencapsulation for food applications. The combination of these ideas could result in a novel method of protecting sensitive food additives, in addition to creating a platform for new techniques in the pharmaceutical and food industries. Bifidobacteria were successfully encapsulated using the novel PGSS method. Two lipid based excipients, Compritol E 472 ATO and Vegetal BM 297 ATO were tested to determine if they could be used in the microencapsulation of bifidobacteria. Results showed that the temperature needed to successfully liquefy the Compritol resulted in high losses of cells. It was decided to continue the study with only Vegetal BM 297 ATO which resulted in much lower losses of probiotic cells. The results demonstrated that the cells were successfully encapsulated inside Vegetal BM 297 ATO microparticles. The particles contained high numbers of cells and the process did not cause any morphological changes on the probiotic cells. The process was optimized by changing the reaction formulation and mixing chamber parameters until an encapsulation efficiency (EE) of 88% was attained. The Vegetal microparticles containing the bifidobacteria were a very desirable size for use in the food industry. This was the first time the use of a lipid based food grade excipient in microencapsulation of probiotics using a PGSS procedure was demonstrated. This result leads to further testing of the Vegetal BM 297 ATO microparticles containing bifidobacteria in in vitro gastrointestinal environments. It was found that the Vegetal BM 297 ATO matrix provided a protective effect on the cells during simulated gastrointestinal transit. There were more viable cultures in the sample containing encapsulated cells after exposure to simulated gastric fluid (SGF) and subsequently simulated intestinal fluid (SIF). The cells were released from the Vegetal BM 297 ATO matrix over 7 hours after an initial decrease in numbers. The viable numbers of non-encapsulated cells continuously decreased while the encapsulated cells continuously increased over time during exposure. The microparticles were subsequently tested to see if they increased the shelf life of bifidobacteria under different storage conditions. It was found that during refrigerated storage the microparticles did not increase the shelf life of bifidobacteria, but that it had a slight protective effect when stored at room temperature.