Probiotics antimicrobial production

The mechanism by which protection is offered by these probiotics has not yet been fully established. However, one or more of the following are possible competition for nutrients, secretion of antimicrobial substances, blocking of adhesion sites, attenuation of virulence, blocking of toxin receptor sites, immune stimulation, and suppression of toxin production. 

Probiotics also play a role in dairy fermentations to assist in the preservation of milk as a result of the production of lactic acid and other antimicrobial compounds. They have other functions as well, which are not involved with preservation or organic acids (Parvez et al., 2006). 

New or improved polysaccharide production by LAB could be used to extend or adjust the textures of many fermented milk products and would have the presumed advantage of being acceptable food ingredients. Some of these polysaccharides, as well as levans, are of interest because of their prebiotic or probiotic properties. Due to a strong demand for natural and minimally processed foods, there has been a growing interest in the use of antimicrobial compounds produced by LAB as a safe and natural way of food preservation. 

As mentioned earlier, supplements are probably the most common format for probiotic consumption, in addition to dairy products. Furthermore, probiotics have been included in fruit juices, which is particularly challenging because of the low pH (<4) and the presence of various natural antimicrobial components in fruits (such as benzoate and anthocyans). Probiotics have also been included in chocolate (Vriens, 2009), providing extremely long shelf lives of up to 2 years - not so much to produce probiotic chocolate bars, but to provide a probiotic-carrying chocolate coating to various foods. These applications fall outside the focus of this chapter, but indicate that formats for probiotics exist. 

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