Direct measurement of pH profiles in gel beads immobilizing Lactobacillus helveticus using a pH sensitive microelectrode |
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Authors: | Fabrice Massen Christophe Lacroix Céline Paquin |
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Institution: | (1) Centre de recherche STELA, Pavillon Paul-Comtois, Université Laval Ste Foy, G1K 7P4 Québec, Canada |
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Abstract: | A H+-selective liquid membrane microelectrode was prepared and used to measure the pH profile evolution during colonization of gel beads immobilizing Lactobacillus helveticus in a whey permeate medium. A large pH gradient was observed in a highly active periferal layer thickness that decreased from 500 to 300 m for an immobilized cell population that increased from 5.8 × 109 to 3.1 × 1010 CFU/g. The flat pH profile (pH 4.4) in the central part of the bead was attributed to a high concentration of the inhibitory undissociated form of lactic acid. |
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