Viability of Microencapsulated Bifidobacteria in Set Yogurt During Refrigerated Storage

Abstract

Bifidobacteria are probiotic organisms that improve the microbial balance in the human gut. They can be incorporated as live cultures in fermented dairy foods, including yogurt, for transmission to humans. Because bifidobacteria are sensitive to high acidity, their viability in yogurt is limited. The objective of the present study was to investigate the effect of microencapsulation on the viability of bifidobacteria in yogurt during refrigerated storage for 30 d. Live bifidobacterial cells were encapsulated in kappa-carrageenan. Cell enumeration, determination of titratable acidity and pH, quantitation of lactic and acetic acids, and sensory evaluation (consumer test) were carried out on the yogurt samples. Microbiological results showed a decline of 78 and 70.5% in the population of Bifidobacterium longum B6 and B. longum ATCC 15708, respectively, for the treatments containing nonencapsulated cells. No difference in bifidobacterial population was observed in the encapsulated treatments. The acetic acid content in the yogurt with nonencapsulated bifidobacteria was higher than that in the plain yogurt (control) and encapsulated treatments. The increase in lactic acid content during storage was not different among the various treatments for B. longum B6, but was greater for nonencapsulated than encapsulated B. longum 15708 and the control. Consumers judged the nonencapsulated treatment as the most sour, which was likely due to the higher acetic acid content. Consumers preferred the control and nonencapsulated treatments over the encapsulated treatment. Microencapsulation appears to increase the viability of bifidobacteria in yogurt. This technique can be used to transmit bifidobacteria via fermented products provided that sensory characteristics of the product are improved or maintained.

Technology and potential applications of probiotic encapsulation in fermented milk products

“…Then, the produced emulsion is broken by adding CaCl 2 and the produced microcapsules are collected by centrifugation. Sodium alginate, κ-carrageenan with KCl as the emulsion breaker and genipin cross-linked gelatin can be used to microencapsulate probiotic bacteria by emulsion method (Adhikari et al, 2002;Adhikari et al, 2000;Annan et al, 2008). It has been reported that concentration and viscosity of the encapsulation mix before gelation, agitation rate of mixture and type of emulsifier used are the main important parameters which control the diameter of the final formed microbeads.…”

“…Microencapsulation is a physicochemical or mechanical process in which the bacterial cells are entrapped within coatings of hydrocolloidal materials, providing protection from adverse conditions such as high acidity and low pH, bile salts, cold shock (induced by process conditions such as deep freezing and freeze drying), molecular oxygen (in the case of obligatory anaerobic microorganisms), heat shock (caused by the process conditions such as spray drying), and chemical antimicrobial agents applied in order to inhibit or reduce cell injuries/loss and increase viability (Korbekandi et al, 2008;Adhikari et al, 2000;Krasaekoopt et al, 2006;Sultana et al, 2000;Mortazavian et al, 2008;Krasaekoopt et al, 2004;Hansen et al, 2002;Lee and Heo, 2000;Rao et al, 1989;Wenrong and Griffiths, 2000;Champagne 2012;Heidebach et al, 2012). Other advantages including increase in sensory stability and/or its improvement and immobilization of the cells for their homogeneous distribution throughout the product, can also be achieved (Mortazavian et al, 2007b).…”

“…Acetic acid produced by Bifidobacterium spp. gives a vinegar taint to the fermented probiotic products such as yoghurt (Adhikari et al, 2000). This off flavor which is mainly produced during the fermentation period develops within storage was added at 2.5 % (w/v).…”

“…The low pH of the stomach and the presence of bile salts in the small intestine are the main reasons for the dramatic decline in viability of delivered cells (Tamime et al, 2005;Kosin and Rakshit, 2006;Korbekandi et al, 2011) . Many investigations have documented the positive effects of microencapsulation of probiotic microorganisms and their survival in fermented milks and gastrointestinal tract (Adhikari et al, 2000;Sultana et al, 2000;Sun and Griffiths, 2000;Krasaekoopt et al, 2004;Picot and Lacroix, 2004;Iyer and Kailasapathy, 2005;Kailasapathy, 2006). Some important applications of microencapsulation in the food industry are summarized in figure 3 (Anal and Singh, 2007).…”

Green tea increases the survival yield of Bifidobacteria in simulated gastrointestinal environment and during refrigerated conditions

“…Several reviews [2] summarized the potential of microencapsulation to improve probiotic survival during storage or gastrointestinal transit. Alginate is the most widely used matrix for microencapsulation, but its use is limited due to low stability in acidic conditions [3,4]. Therefore coating of alginate with chitosan improved the stability of alginate beads and thus improved the viability of the encapsulated probiotic bacteria, as previously shown by Krasaekoopt et al [5].…”