6533b7d9fe1ef96bd126bdeb

RESEARCH PRODUCT

Screening of lactic acid bacteria based on their reduction kinetics

subject

description

Lactic Acid bacteria (LAB) are widespread in the dairy industry for their use as starters and probiotics. They are able to reduce redox potential (E h) of food matrices, influencing oxidation-reduction reactions involved in the organoleptic quality of the product and also preventing the development of undesired microflora. Amongst LAB, some species are able to reduce E h below negative values while others do not [1]. This diversity of reducing activity found in LAB allows the use of selected strains providing optimal reduction values necessary to the overall quality of food dairy products. Currently, there are different ways to compare LAB based on their reducing properties. Cachon et al., 2002 proposed the Potentiometry Reduction Activity Method (PRAM) by monitoring E h in liquid medium with redox probes, and the comparison of the maximum reduction rate (Vmax r), and the time to reach Vmax r. Michelon et al., 2013 proposed the cOlorimetric Reduction CApacity Method (ORCAM), a screening method on solid medium. This later takes advantage over PRAM to allow screening of a lot of strains in a short time. Nevertheless, this method is relatively non-discriminatory between LAB strains belonging to the same species. Consequently, we developed a new method, the Absorbance Reducing Activity Method (ARAM), in order to differentiate strains by keeping the simplicity of ORCAM but with the relevance of bacterial reduction kinetics obtained with PRAM. To validate this new screening method, PRAM using iCinac interface was carried out in parallel as reference method.