A prototype of time temperature integrator (TTI) with microbeads-entrapped microorganisms maintained at a constant concentration

Abstract

The existing microbial TTIs based on lactic acid production have some weakness that their kinetics includes both the microbial growth and the lactic acid production. Such weakness was improved by applying SPG (Shirasu porous glass) membrane emulsification to produce microbeads entrapping microorganisms, resulting in maintaining constant microbial levels throughout the use periods and considering only lactic acid production in kinetics. The TTIs containing the microbeads with the initial concentration of 10.7 log CFU/g of Weissella cibaria CIFP 009 maintained the microbial level constant during the use, while the TTIs with less initial levels (6.2 and 9.3 log CFU/g) showed a slight increase. A wide range of TTI response (pH) rates in zero-order reaction were obtained by varying the amounts of the microbeads in TTI formulations. In addition, the lag phase common to microbial growth was not manifested in the pH change, which facilitates an immediate TTI response after activation. In conclusion, the application of the microbeads to microbial TTI could provide the wide response rates in zero-order and the absence of lag phase favorable to an ideal microbial TTI. (C) 2013 Elsevier Ltd. All rights reserved.