Synbiot production and encapsulation

Abstract

The use of probiotics and prebiotics has become a popular trend in the food industry. The main goal of this study was to produce a synbiot by encapsulating a probiotic and a prebiotic within a matrix that would provide sufficient protection to the probiotic against simulated gastric juice (SGJ). The ability of the probiotic, Bifidbacterium adolescentis, to grow on short chain fructooligosaccharides (FOS; DP 2-8, P95), inulin (DP 2-60, ST), and FOS/inulin mixture (DP 2-60, Syn), as well as glucose and a glucose-free maltooligosaccharide (MOS), were evaluated. Bifidobacterium adolescentis had a significantly higher specific growth rate on P95 (0.47 h-1), than glucose (0.40 h-1). Examination of the growth medium containing P95 and MOS by high performance anion exchange with pulsed amperometric detection (HPAE-PAD) revealed that B. adolescentis utilised the oligosaccharides to the same extent as the monosaccharides. Bifidobacterium adolescentis was successfully encapsulated with and without P95 using extrusion and emulsion methods, at cell concentrations of 8-9 log colony forming units (CFU) mL-1. Capsules formed by the extrusion method with 1.0% alginate (AL), 4.0% pea protein isolate (PPI) + 0.5% AL, and 4.0% whey protein isolate (WPI) + 0.5% AL ranged in geometric mean diameter from 2.0 to 2.2 mm. Capsules formed by emulsion with 4.0% WPI + 0.5% AL had geometric mean diameter of 53 ìm. Extrusionbased encapsulated probiotics in either PPI + AL or WPI + AL showed improved survival in SGJ at pH 2.0 for 2.0 h with log CFU mL-1 reductions of 3.6 and 1.1, respectively. Free cells, AL extrusion-based and WPI + AL emulsion-based encapsulated probiotics showed no survival after 30 min in SGJ at pH 2.0. The addition of 1.0% (w/w) P95 to the PPI + AL capsules improved probiotic survival such that 1.0 log CFU mL-1 reduction was observed. The amount of P95 encapsulated ranged from 4.0 to 4.4 mg per gram of capsules. The external surface of the PPI + AL capsules as examined by cold stage scanning electron microscopy (cryo-SEM) and atomic force microscopy (AFM) was smooth with the presence of pores ranging in diameter from 0.25 to 1.00 ìm. The addition of P95 to the capsules had no significant effect on surface roughness as measured by AFM, but significantly increased the external capsule thickness. The internal structure of the PPI + AL capsules examined by cryo-SEM revealed a porous honeycomb-like structure, with inner pore diameters ranging between 13.0 and 21.9 ìm. Probiotic cells were found to be randomly dispersed on the surface and in the interior of the honeycomb pores. In contrast, the prebiotic was found to be distributed throughout the capsule as observed by confocal laser scanning microscopy (CLSM), indicating that it would be readily available to the probiotic as a carbon source