ANSWER
Most commercially available probiotics are non-spore forming lactic acid bacteria, namely Lactobacilli, Bifidobacteria and Enterococci. However, not all strains of Lactobacilli and Bifidobacteria can be used as components of probiotics but only those that are of human origin, non-pathogenic, resistant to gastric acid, bile and to the antibiotics (Denkova and Krastanov, 2012).
There are several factors that could affect the viability of probiotic cultures including pH, hydrogen peroxide, dissolved oxygen content, storage temperature, species and strains of associative fermented dairy product organisms, concentration of lactic and acetic acids and buffer (Maleki et al., 2015).
Microencapsulation is a process where the cells are retained within an encapsulating membrane to reduce cell injury or cell loss. It has proved that microencapsulation enhanced the survival of probiotic cultures compared to free cells. It is a strict term would apply to particles of size 0.2 – 5000μm while those larger than 5000 μm are classified as macro and those smaller than 0.2μm are classified as nano-microcapsules (Maleki et al., 2015).
There is a need for encapsulation of probiotic bacteria to survive in human gastric juice in the stomach where the pH can be as low as 2. Microencapsulation of bacterial cells is new methodology for extending their storage life in which are currently gaining much attention. By converting them into powder form, it increases the viability of probiotic bacteria in acidic products such as yogurt as this technology segregates the cells from adverse environment which potentially reduce cell injury (Maleki et al., 2015).
Several lesser effective techniques would include spray drying, freeze drying, fluidized bed drying for encapsulating the cultures and converting them into a concentrated powdered form. However, the bacteria encapsulated by these techniques are completely released in the product thus not protecting the cultures from the product environment or during the passage through the stomach or intestinal tract (Maleki et al., 2015).
References
Maleki, D., Azizi, A., Vaghef, E., Balkani, S. & Homayouni, A. (2015). Methods of Increasing Probiotic Survival in Food and Gastrointestinal Conditions. Prensa Med Argent, 101(4), 1-9.
Denkova, Z. & Krastanov, A. (2012). Development of New Products: Probiotics and Probiotic Foods. Probiotics, 81-120. https://doi.org/10.5772/47827
